Macht Isometrics –Auf Deutsch (Tierreich-Training 1) (German Edition)

Inour case, this leads to sized vectors. We then label each vector with theterrain type it corresponds to. Except for grass, they appear very similar to a human. Next, we transform the raw acceleration signals to the frequency domain. In[6], we compared different transformations. The normalization prevents features with highmagnitude from dominating the training. Some example acceleration vectors for asphalt, gravel, grass and clay. D denotes the length of the feature vectors. Each candidateparameter vector ,C on the grid is evaluated by 5-fold cross-validation.

Thegrid parameters are standard ones that are often used in other applications, too. In the classification phase, the robot traverses unknown terrain and collectsvibration signals. Once per second, it creates a test vector from the accel-eration values taken during the last second and transforms the vector using theFFT.

Additionally, the robot normalizes the feature vector using the same pa-rameters used during training. Then, the trained SVM classifies the test vectorand returns the estimated terrain type. The reason is thatbumps in the terrain are likely to have their major effect in up-down direction. However, the accelerations measured in other directions, e.

Our experiments pre-sented in Section 3 show that these accelerations may even be more suitable forclassification than the data measured in z direction. In addition,many acceleration sensors are able tomeasure accelerations alongthree axes simultaneously. For robots equipped with such a sensor, we propose asimple but effective method to improve classification.

For each terrain segment,we collect the acceleration signals along all three axes, in our case front-back x ,left-right y , and up-down z. Then, we transform the signals individually by4 C. Next, we concatenate the transformed feature vectors and normalizethe features. We then train the SVM on these feature vectors. In the classification phase, we perform the same steps to get a test vectorcontaining information about all three directions of accelerations. Finally, weclassify the test vector using the SVM.

We mounted an Xsens MTi sensor on an aluminium plate on top of the robot. The sensor measures the acceleration in x, y and z direction simultaneously at Hz. In total, we collected terrain vectors, some of them in mid-July andsome in the beginning of December. Each terrain vector corresponds to 1 s ofrobot travel. The terrain vectors differ in the type of terrain and in the velocity ofthe robot. As terrain types, we used indoor floor, asphalt, gravel, grass, paving,clay a boule court , and the situation in which the robot did not move Fig.

The velocity of the robot was one of 0. For evaluation, we used fold cross validation, i. In eachfold, we used 9 parts for training and the 10th part for testing. The final resultis the mean over the results of the individual folds. We expected that higherspeeds of the robot would lead to stronger vibrations and therefore to clearervibration signals. However, the 3-class experiments did not confirm this expec-tation. Data collected at 0.

Number of samples per class in our datasetclass 0. Experimental results using a 3 terrain classes, b 7 terrain classes. However, in experiments on allvelocities mixed together in one dataset, the classification rates decrease. The experiments show that the vibration measured in y direction leads tobetter results than the vibrationmeasured in x or z direction. The y data leads toclassification rates of about When combining the data fromall three directions, the results get even better. On the mixed dataset, In these experiments, the results for data collected at 0. Again, vibrationdata measured in y direction are classified better than data of the other direc-tions.

Additionally, x data yields to better results than z data. The classificationrates for the y data are When using combined data from all velocities, the classification ratesagain increase significantly to between According to the confusion matrix, the classesno motion and grass are unproblematic, because they are confused with otherclasses in very few cases.

Gravel and paving seem to be relativelysimilar. For clay,there is no clear trend towards misclassifiying it as a particular class. The time for training depends on the dataset. For example,training in the 3-class experiment on y data collected at 0. This dataset contains feature vectors. Another example is the7-class dataset with combined acceleration directions and mixed speeds. Thisdataset contains feature vectors, and training takes about 14 h 24 min.

Additionally, we presented atechnique to improve the classification by using vibrations measured in differentdirections. A comparison between data measured in front-back x , left-right y andup-down z direction showed that the y data leads to significantly better classi-fication rates than the z data. Neverthe-less, the result shows that it is worth trying some other measurement directionsbefore relying on the up-down vibration. Our experiments showed that if therobot is able to measure the acceleration in multiple directions simultaneously,including all available information into the feature vector significantly improvesthe classification rate.

For future work, we plan online learning, where the new information of thetest phase is integrated into the model. The robot should also be able to noticeif it traverses some terrain that it has never traversed before. Machine Learning, 20, pp. A Library for Support Vector Machines. SLAM mechanisms are a key component towards advancedservice robotics applications. Currently, a major hurdle are the still highcosts of suitable range measuring devices. A solution are bearing-onlySLAM approaches since these can be used with cheap sensors like omni-cams.

Instead of artificial landmarks, we now use SIFTfeatures [3] as natural landmarks. Weexploit viewing areas to massively reduce ambiguities and mismatches inSIFT feature reobservations and thus significantly reduce false identifierassignments. The approach has been successfully evaluated on a Pioneer-3DX platformin an unmodified indoor environment.

The results show that bearing-only SLAM produces reliable results even with cheap vision sensors andnatural landmarks. This is best implemented based on pose know-ledge. Of course, there is a large body of work available on pose estimation, posetracking, relocalization or SLAM simultaneousmapping and localization. How-ever, one cannot neglect the specific demands on service robots. For instance, inmost applications of service robots the consumer neither accepts modificationsof the environment like artificial landmarks nor complex and time consumingdeployment efforts.

Thus, a SLAM component based on cheap sensors work-ing without artificial landmarks is a key technology for many service roboticapplications. As long as no calibrated systems are needed, omnicams are cheap and smalland thus suitable for service robots. Although omnicams provide feature richinformation on the surrounding of the robot with high update rates, they do notprovide range information.

Thus a bearing-only SLAM approach is applied thatonly requires observation angles of landmarks. The SLAM state vector comprises the robot pose x, y, and 2d landmark poses xi, yi. Depending on the parameter settings, a single omnicam image containsup to several hundred SIFT features.

However, the EKF based approach showstwo characteristics that need to be adressed. It does not scale well with increasingnumbers of landmarks and it is very brittle with respect to false landmark iden-tifications. Thus one needs a very robust mechanism to select a small but stablenumber of SIFT features in an image.

These have to be distributed sparsely overthe image and should also possess characteristic descriptor values to avoid falseassignments. This paperuses the exactly same approach but replaces the artifical landmarks coloredcylinders by natural landmarks described by SIFT features. The iterative SIFTapproach is based on a particle filter [5]. However, due to the particle filter,a much higher number of keypoints is needed compared to our approach. Inour case, a small number of keypoints is even mandatory and we can set theSIFT parameters such that only very stable keypoints survive.

Another particlefilter based approach that estimates 3d landmark poses based on SIFT features ispresented in [6]. A highly sophisticated monocular SLAM approach that extendsbeyond robotics is presented in [7]. Each featurevector is invariant to scaling, rotation or translation of an image. SIFT featuresare also very resilient to the effects of noise in an image.

Thus, SIFT featuresare means to describe natural landmarks. For instance, we do not have to relyon specific shape or color models. SIFT features of an image are calculated by four steps executed consecutively. We apply the plain calculation scheme described in detail in [3]. The first stepis named scale-space extrema detection. In our case, we use an omnicam imageof size x The first octave consists of five images, that is the originalimage and another four images. The latter are obtained by repeatedly convolvingthe original image with Gaussians. We use a -value of 2.

This parameter isvery stable and can thus be determined empirically. A larger value increasesthe computational load without improving the re-recognition of SIFT features. It is set such that the output of the overall processing chain is a stable set ofroughly 30 SIFT features. Now the four DOG difference of gaussians imagesare calculated. Finally, extrema are detected in the two inner DOG images bycomparing a pixel to its neighbors in 3x3 regions.

We use a down-sampling10 S. Schlegelfactor of 2 where downsampling ends at an image of 4x4 pixels. Therefore, weconsider 7 octaves. The second step is named keypoint localization. The contrastthreshold is set to 0. Wefirst set it such that we obtain stable landmarks. Then we modify this thresholdto reduce the number of obtained landmarks.

Finally we modify it to reducethe computational load without further reducing the number of landmarks. Thecurvature threshold r is set to 10 same as Lowe. The third step is namedorientation assignment. Since we do not further exploit the orientation value,we omit this step. The fourth step is named keypoint descriptor. The result are SIFT feature vectors each of dimension with 8bit entries. It is importantto note that we only use the observation angles of landmarks in the omnicamimage. The observation angle of a landmark in the omnicam image is equivalentto the yaw-angle of the landmark in the 3d-environment when using polar-coordinates pitch , yaw , distance d.

As can be seen in figure 2, the imagedistortion of the omnicam does not affect the observation angle. Of course, alllandmarks with the same yaw-angle but different pitch-angles possess thesame observation angle. In case of distinct SIFT feature vectors, we just havedifferent landmarks at the same observation angle. Otherwise, the same featuresoccured at the same yaw-angle but at different pitch-angles and thus need notto be discriminated. Now SIFT features areextracted based on the standard attributes gaussian filter, contrast, curvatureratio.

Since the omnicam image also comprises the robot and mountings of thecam, we finally remove all SIFT features in those areas by a simple maskingoperation. Then the current robot pose gets a unique index and is added tothe EKF state vector as image acquisition pose to allow for delayed featureinitialization as described in [1][2]. Each SIFT feature descriptor of the currentimage gets labeled by the above pose index. However, we only considerthose images where the euclidean distance to the image acquisition pose is lessthan two times themaximum viewing distance of the omnicam in our case 15m.

Next the euclidean distance between the current SIFT feature vectors and theremaining ones of the previous step are calculated. A SIFT feature of the current image is considered as not matching an alreadyknown landmark either initialized or not initialized landmark if the ratio of thesmallest and second smallest distance value is above a given threshold value 0.

In that case, this SIFT feature gets a new and unique identifier. This SIFTfeature is the first observation of a potentially new landmark first measurementof an uninitialized landmark. Otherwise, the SIFT feature is considered as matching an already knownlandmark. In this case we have to check whether the SIFT feature matched aninitialized or an uninitialized landmark. In the first case, the considered SIFTfeature is just a reobservation of an already known landmark.

This now is val-idated by a Mahalanobis distance based test [4]. In case this test is passed,the measurement is forwarded to the EKF as reobservation of the initializedlandmark. Otherwise, the current measurement and its SIFT feature is the firstobservation of a potentially new landmark first measurement of an uninitializedlandmark. In the second case, we solely have several observations bearing-only mea-surements of the same SIFT feature uninitialized landmark from different ob-servation poses. Since in that case we cannot apply the Mahalanobis distance, weuse geometrical reasoning for validating the reobservation.

The new observationcan belong to the uninitialized landmark only if its viewing direction intersectsthe visual cone given by the previous measurements of this uninitialized land-mark. In that case this SIFT feature is considered as a new observation of thisnot yet initialized landmark. Otherwise this SIFT feature is the first observationof a potentially new landmark first measurement of an uninitialized landmark.

Assignment of identifiers to SIFT-features. Thus, wecannot apply the Mahalanobis distance to validate the assignment. Therefore, weapply a simple geometrical validation scheme that reliably sorts out impossiblematches. In figure 4, P2 denotes the current robot pose with a being the vectortowards the previous robot pose P1 and c2 limiting the viewing range.

At P1 alandmark L has been seen with heading b and a maximum distance as indicatedby c1. Thus, L can only be seen from P2 in case its observation angle is in therange r. Geometrical validation of matches. The sensing steps 5, 9, 35, 40, 52, 53, 54 and 56 of a 75 step run with closinga loop. The ellipsesshow the 2-sigma contour. The threshold of the Kullback-Leibler distance is setto 12 see [1].

This value is derived from a 1-pixel jitter in the omnicamimage. The experiments havebeen conducted in a standard indoor environment. Therefore, we have not takenany precautions to avoid direct sunlight, specular reflections and differences inbrightness. Further experiments can be found at [8]. Thus, no methods to correct image distortion or perspective areneeded. The conducted experiments show quick and reliable convergence towardsa stable SLAM system. The different parameters are robust, can be set in wideranges and can thus be determined with low effort.

Distinctive image features from scale-invariant keypoints. InternationalJournal of Computer Vision, Robotics and Autonomous Systems 54 9: Palma de Mallorca, Spain, In this this paper, we present a solution to the simultaneous localiza-tion and mapping SLAM problem for a robot equipped with a single perspectivecamera. We track extracted features over multiple frames to estimate the depth in-formation. To represent the joint posterior about the trajectory of the robot and amap of the environment, we apply a Rao-Blackwellized particle filter.

We presenta novel method to match features using a cost function that takes into accountdifferences between the feature descriptor vectors as well as spatial information. To find an optimal matching between observed features, we apply a global opti-mization algorithm. Experimental results obtained with a real robot show that ourapproach is robust and tolerant to noise in the odometry information of the robot.

Furthermore, we present experiments that demonstrate the superior performanceof our feature matching technique compared to other approaches. Without an ap-propriate model of the environment, for example, delivery tasks cannot be carried outefficiently. A large group of researchers investigated the so-called simultaneous local-ization and mapping SLAM problem.

The majority of approaches focuses on prox-imity sensors to perceive the environment such as laser range finders, sonars, radars, orstereo vision cameras. In this paper, we address the problem of learning maps using a mobile robotequipped with a single perspective camera only. Compared to a laser range finder, cam-eras have the advantage that they are cheap and lightweight.

One of the problems, how-ever, is the missing distance information to observed landmarks. This information is notprovided by a perspective camera. We present a mapping system that can use this sensorsetup to learn maps of the environment. Our approach applies a Rao-Blackwellized par-ticle filter to maintain the joint posterior about the trajectory of the robot and the mapof the environment.

We furthermore present a novel method to establish the data asso-ciation between features. It takes into account the individual feature descriptor vectorsas well as spatial constraints. Our approach is able to compute the optimal matchingbetween observed and already tracked features. To achieve this, we apply the Hungar-ian method which is an efficient global optimization algorithm. Experiments carriedout with a real robot illustrate the advantages of our technique for learning maps withrobots using a single perspective camera.

The system works reliable in room-size en-vironments but is restricted in the number of landmarks it can handle. Landmarks arematched by looking back into the image at the expected region and by perfoming a lo-cal match. SIFTfeatures [5] in both cameras are matched using their description vectors as well as theepipolar geometry of the stereo system.

The matching between observations and land-marks is done using the SIFT descriptor only. In the bearing-only algorithm of Lemaireet al. The Gaussiansare initialized along the first observation and they are pruned in the following frames. It allows the robot toefficiently model the joint posterior in a sampled fashion. To obtain landmarks, we extract speeded-up visual features SURF [7] out of thecamera images. These features are invariant to translation and scale.

They can be ex-tracted using a Fast-Hessian keypoint detector. The dimensional feature descriptorvector d is computed using horizontal and vertical Haar wavelet responses. A rotationaldependent version of SURF is used since the roll angle of the camera is fixed when it isattached to a wheeled robot. In order to obtain spherical coordinates of a feature given its position in the image,we apply a standard camera model. In this way, pixel coordinates of detected keypointsare transformed into the azimuthal angle and the spherical angle. The distance tothe observed feature cannot be measured since we use only a monocular camera.

Thetuple , is referred to as bearing-only observation z. Each landmark l ismodeled by a 3D Gaussian ,. Moreover, we assume data association problem be-tween observed features and landmarks is solved. These assumption are relaxed in thesubsequent sections. For eachcomplete assignment of the currently observed features to map features, an update ofthe Rao-Blackwellized particle filter is carried out. To achieve this, we have to apply two transformations. The uncertainty over the depth is set to a high value in order to represent the bearing-only aspect of the update.

We weight each particle k with respect to its observation likelihood. We track fea-tures over consecutive frames and estimate the depth of the features using discreteprobability distributions similar to [1] but in a bottom-up manner. When a feature f isinitially observed, a 3D ray is cast from the camera origin o towards the observed fea-ture.

Equally weighted bins b[ j] representing different distances [ j] are distributeduniformly along this ray within a certain interval. This reflects the fact that initiallythe distance to the feature is unknown. To get an estimate about the depth of the fea-tures, they are tracked over consecutive frames the next subsection explains the featurematching process. In case the initial feature f is matched with a feature f in the con-secutive frame, the bins are projected back into that frame.

They lie on the so-calledepipolar line [8], the projection of the 3D ray into the image. The depth hypotheses [ j]are weighted according to the distance to the pixel location of feature f using a Gaus-sian model. Figure 1 illustrates the estimation process for two features in consecutiveframes. This figure shows the depth estimation process for two features crosses. A ray iscast from the camera origin through the initial feature. The ray is re-projected in theconsecutive frame. This line dashed is called epipolar line. Depth hypotheses circles weredistributed uniformly on the ray in the Cartesian space, which results in an irregular distribution inthe image space.

Hypotheses are weighted according to their distance to the correspondingfeature. Depth Estimation as Preprocessing Step The robots pose at the point in time, whenthe corresponding feature is observed initially, determines where the 3D ray is locatedin the world. Navely, for each particle a histogram of depth hypotheses has to be main-tained so that the bins can be updated accordingly to the individual particle poses. How-ever, this would lead to an overhead in computation time and memory. Fortunately, itis possible to maintain a depth histogram independently of the particles. The 3D ray isdescribed by the angles , and an arbitrary origin o.

Over the following n frames, therelative motion is added to o, so that the projection of the hypotheses positions into thecurrent frame can be calculated. Since the motion noise for wheeled robots is negligiblewithin n frames, it can be omitted for the depth estimation process only. Landmark Initialization Once a feature is reliably tracked and the depth of a feature isestimated, a landmark l is initialized.

This has to be done for each particle k individually. Using the particle pose at the time t f when feature f was observed for the first time, theglobal Cartesian landmark position can be calculated byl: Thisis done using the Hungarian method [9]. The Hungarian method is a general methodto determine the optimal assignment under a given cost function. In our case, we use acost function that takes into account differences of the feature descriptor vectors as wellas well as spatial information to determine matches between observations and trackedfeatures as well as between observations and landmarks.

Visual Bearing-Only Simultaneous Localization and Mapping 19Feature Matching Intuitively, features that are tracked to obtain the correspondingdepth can be matched based on their descriptor vectors using the Euclidean distance. However, this approach has a serious short-coming. Its performance is low on similarlooking features since it completely ignores the feature positions. Thus, we instead usethe distance of the descriptor vectors as a hard constraint. Only if the Euclidean distancefalls below a certain threshold, a matching is considered.

We define the cost functionby means of the epipolar line introduced in Section 3. By setting the matching costto the distance of the feature to this line in the image space see Figure 2 , not only thepixel locations of the comparing features are considered but also the relative movementof the robot between the corresponding frames is incorporated. Landmark Matching Using Observation Likelihoods Similarly, during the match-ing process between landmarks and observations we use the distance of the descriptorvectors as a constraint.

Landmarks are matched with observations using their positions. Since the observations are bearing-only, the distance to the landmark position cannotbe computed directly. For this reason, the observation likelihood in Eq. It ishigh if and only if the distance between the observation and prediction is small. If the observa-tion likelihood lies below a certain threshold, the cost are set to a maximum value. Thisrefers to the fact that the features are regarded as different features with probability one. The robot was steered througha 10m by 15m office environment for around 10 minutes.

Two camera frames per sec-ond and odometry data was recorded. In addition, laser range data is stored in order tocalculate a ground truth estimate of the robots trajectory using scan matching on thelaser data [10].

Full text of "Catalog of Copyright Entries Books and Pamphlets July-Dec 3D Ser Vol 9 Pt 1"

The results are illustrated in Figure 4. Theerror in the orientation averages 3. Using the odometry of the robot only, one obtainsan average error of 1. We compared our feature matching approach using the Hungarian method on thedistance to the projected line to other three techniques. Figure 5 shows a qualitativeFig. The cost function is set to thedistance between the epipolar line and the feature locationin the image space. Wheeled robotequipped with a perspectivecamera. The robots trajectory is shown on the left, the corresponding error functions and uncer-tainty are shown on the right.

If the robot explores an unknown environment, the error valuesgo up as well as the uncertainty. As soon as the loop is closed, the estimation error and uncertaintydecreases, whereas the odometry error still goes up. Furthermore, we compare the Hungarianmethod quantitatively to the nearest neighbor approach, both using the distance to theepipolar line as cost function. This number obtained by four different sequences of images each can be explained by the fact that mismatches are likely to yield too highvariances in the depth estimation.

Landmarks, however, are initialized only if the depthcan be estimated with low variance. By manual inspection, one can see that the dataassociation has less errors than the nearest neighbor approach see Figure 5. Our approach applies a RBPF to main-tain the joint posterior about the trajectory of the robot and the map of the environment. Using our approach, the robot is able to compute the optimal data association betweenobserved and already mapped features by applying the Hungarian method. Experimentscarried out with real a robot showed the effectiveness of our approach.

Starting from the current frame at time t, we look back to evaluate how many features inthe current frame were reliable tracked over the last four frames. The nearest neighbor assign-ment on SURF descriptors left results in 10 matches and 12 mismatches, whereas our approachresults in 20 matches and 4 mismatches right. Our approach also outperforms the two othercombinations: Real-time simultaneous localization and mapping with a single camera. Real-time single camera SLAM. A factored solution theto simultanieous localization and mapping problem.

Distinctive image feature from scale-invariant keypoints. A practical bearing-only SLAM algorithm. Speeded up robust features. Hartley R and Zisserman A: Multiple View Geometry in Computer Vision. Cambirdige uni-versity press, second edition, The Hungarian method for the assigment problem. Naval Research LogisticQuaterly, 2: Lu F and Milios E: Robot pose estimation in unkown environments by matching 2d rangescans. Autonomous exploration is a frequently addressed problem in the ro-botics community.

This paper presents an approach to mobile robot explorationthat takes into account that the robot acts in the three-dimensional space. Ourapproach can build compact three-dimensional models autonomously and is ableto deal with negative obstacles such as abysms. It applies a decision-theoreticframework which considers the uncertainty in the map to evaluate potential ac-tions.

Thereby, it trades off the cost of executing an action with the expectedinformation gain taking into account possible sensor measurements.

1. ;
2. How Are Things In Glocca Morra.
3. Progressive Grammar for Kids (Workbook)!
4. Hilmar Hoffmann-The Triumph of Propaganda Film and National Socialism, 1933-1945(1997).
5. ?
6. JumpStart Your Greatness!: How You Can Use Powerful Success Secrets, Stories, and Tools to Create More Success in Your Life!.
7. !

We presentexperimental results obtained with a real robot and in simulation. So far, mostapproaches to mobile robot exploration assume that the robot lives in a plane. Theytypically focus on generating motion commands that minimize the time needed to coverthe whole terrain [1,2]. A frequently used technique is to build an occupancy grid mapsince it can model unknown locations efficiently. The robot seeks to reduces the numberof unobserved cells or the uncertainty in the grid map.

In the three-dimensional space,however, such approaches are not directly applicable. The size of occupancy grid mapsin 3D, for example, prevents the robot from exploring an environment larger than a fewhundred square meters. Whaite and Ferrie [3] presented an exploration approach in 3D that uses the entropyto measure the uncertainty in the geometric structure of objects that are scanned witha laser range sensor.

In contrast to the work described here, they use a fully parametricrepresentation of the objects and the size of the object to model is bounded by the rangeof the manipulator. They sample candidate viewpoints within this polygon anduse 2D ray-casting to estimate the expected information gain. In contrast to this, ourapproach uses an extension of 3D elevation maps and 3D ray-casting to select the nextviewpoint.

Gonzalez-Banos and Latombe [5] also build a polygonal map by mergingsafe regions. Similar to our approach, they sample candidate poses in the visibilityrange of frontiers to unknown area.

But unlike in our approach, they build 2D mapsand do not consider the uncertainty reduction in the known parts of the map. The contribution of this paper is an exploration technique that extents known tech-niques from 2D into the three-dimensional space. Our approach selects actions that re-duce the uncertainty of the robot about the world and constructs a full three-dimensionalAutonomous Exploration for 3D Map Learning 23model using so-called multi-level surface maps.

It reasons about the potential measure-ments when selecting an action. Our approach is able to deal with negative obstacleslike, for example, abysms, which is a problem of robots exploring a three-dimensionalworld. Experiments carried out in simulation and on a real robot show the effectivenessof our technique. MLS maps use a two-dimensional grid structure that stores differ-ent elevation values.

In particular, they store in each cell of a discrete grid the height ofthe surface in the corresponding area. In contrast to elevation maps, MLS maps allow usto store multiple surfaces in each cell. Each surface is represented by a Gaussian withthe mean elevation and its uncertainty. In the remainder of this paper, these surfacesare referred to as patches. This representation enables a mobile robot to model environ-ments with structures like bridges, underpasses, buildings, or mines. They also enablethe robot to represent vertical structures by storing a vertical depth value for each patch.

In the 3D case, especially in outdoor environments, we additionally have totake into account the slope and the roughness of the terrain, as well as negative obstaclessuch as abysms which are usually ignored in 2D representations. Each patch p will be assigned a traversability value p [0,1].

A value of zerocorresponds to a non-traversable patch, a value greater zero to a traversable patch, anda value of one to a perfectly traversable patch. In order to determine p , we fit a planeinto its local 8-patch neighborhood by minimizing the z-distance of the plane to the ele-vation values of the neighboring patches. We then compute the slope and the roughnessof the local terrain and detect obstacles. The slope is defined as the angle between thefitted plane and a horizontal plane and the roughness is computed as the average squaredz-distances of the height values of the neighboring patch to the fitted plane.

The slopeand the roughness are turned into traversability values s p and r p by linear interpo-lation between zero and a maximum slope and roughness value respectively. The latter is important for avoiding abysms inthe early stage of an exploration process, as some neighboring patches are below theedge of the abysm and therefore are not visible yet see Fig. Next,we iteratively propagate the values by convolving the traversability values of the patchand its eight neighboring patches with a Gaussian kernel.

For non-existent neighbors,we assume a value of 0. The number of iterations depends on the used cell size andthe robots size. In order to enforce obstacle growing, we do not perform a convolution24 D. Identifying the best viewpointis a two step procedure in our system. First, we define the set of possible viewpoints orcandidate viewpoints. Second, we evaluate those candidates to find the best one. However, this is only feasible if the evaluationof candidate viewpoints is computationally cheap. If the evaluation is costly, one hasto settle for heuristics to determine a smaller set.

A popular heuristic is the frontierapproach [2] that defines candidate viewpoints as viewpoints that lie on the frontierbetween obstacle-free and unexplored areas. In our approach, a patch is considered asexplored if it has eight neighbors and its uncertainty, measured by the entropy in thepatch, is below a threshold. Additionally, we track the entropy as well as the number ofneighbors of a patch. If the entropy or number of non-existing neighbors cannot be re-duced as expected over several observations, we consider it to be explored nonethelesssince further observations do not seem to change the state of the patch.

A frontier patch is defined as an unexplored patch with at least one explored neigh-boring patch. Most of these patches have less than eight neighbors and therefore areconsidered as non-traversable, since they might be at the edge of an abysm. Therefore,we cannot drive directly to a frontier patch. Instead, we use a 3D ray-casting tech-nique to determine close-by candidate viewpoints.

A patch is considered as a candidateAutonomous Exploration for 3D Map Learning 25viewpoint, if it is reachable and there is at least one frontier patch that is likely to be ob-servable from that viewpoint. Instead of using ray-casting to track emitted beams fromthe sensor at every reachable position, we use a more efficient approach. We emit vir-tual beams from the frontier patch instead and then select admissible sensor locationsalong those beams. This will reduce the number of needed ray-casting operations as thenumber of frontier patches is much smaller than the number of reachable patches.

In practice, we found it useful to reject candidate viewpoints, from which the un-seen area is below a threshold. We also cluster the frontier patches by the neighboringrelation, and prevent patches from very small frontier clusters to generate candidateviewpoints. This will lead to a more reliable termination of the exploration process. Candidate viewpoints of an example map are shown in Fig. As the evaluation involves a costly 3D ray-castingoperation, we reduce the set of candidate viewpoints by sampling uniformly a fixednumber of viewpoints from that set.

In order to simultaneously determine the shortest paths to all candidate viewpoints,we use a deterministic variant of the value iteration [7]. A constant factor w is used to weight the penalization fortraversing poorly traversable patches. The travel costs t v of a viewpoint v is definedas the accumulated step costs of the shortest path to that viewpoint. In order to evaluate the information gain of a viewpoint candidate, we perform a ray-cast operation to determine the patches that are likely to be hit by a laser measurementsimilar to [8]. We therefore determine the intersection points of the cell boundariesand the 3D ray projected onto the 2D grid.

Next we determine for each cell the heightinterval covered by the ray and check for collisions with patches contained in that cellby considering their elevation and depth values. Using a standard notebook computer,our approach requires around 25 ms to evaluate one potential viewpoint including the3D ray-cast operation. This allows us to run our algorithm with minimal delays only fortypical environments. For each casted ray that hits a patch, we temporary add a new measurement into thepatchs grid cell with a corresponding mean and variance that depends on the distanceof the laser ray.

The mean and variance of the patch will then be updated using theKalman update. Additionally, we add a constant value for each empty cell traversed by the ray. In thisway, we reward viewpoints from which unseen areas are likely to be visible, whilewe are still accounting for the reduction of existing uncertainties in the known map. Rays that do not hit any patch and do not traverse any empty cells, will result in aninformation gain of zero. The information gain I v of a viewpoint v is then definedas the sum of the information gains of all casted rays. We therefore cannot drive directly to the next viewpoint,as the resulting overlap with the previous local map may be to small.

Hence, we performseveral 3D scans along the way, which has the benefit, that it allows us to optimize thelocalization of the robot with the pose returned by the scan matcher. We apply a 6DMonte Carlo localization proposed by Kummerle et al. After each 3D scan, wereplan the path to the selected viewpoint. If the viewpoint is unreachable, we choose anew one. The exploration terminates if the set of candidate viewpoints is empty.

For the real-world experiments we used an ActivMedia Pioneer2-AT robot with a SICK laser range finder mounted on a pan-tilt unit to acquire three-dimensional range data. For a 3D scan we tilt the laser in a range of 40 degrees at fourequally spaced horizontal angles while acquiring the laser data. We tested our approach in simulation and in a real-world scenario. For the simula-tion experiments, we used a physical simulation environment that models our Pioneerrobot with its pan-tilt unit. The simulated indoor environment consisted of four rooms,each connected to a corridor, and a foyer where the robot is located initially.

The uppertwo rooms are connected directly through a door, while the lower ones are not. Therobot efficiently covered the environment taking into account its constraints like travelcost, and information gain. The robot traveled 59 meters, visited eight viewpoints, andperformed 15 scans see Fig. The final map, depicted in Fig. Real-world experiments have been carried out on the university campus. In the ex-periment shown in Fig. The map depicted in Fig. One can see four rooms, a corridor,and the foyer where the robot started the exploration.

One can see the walls of three buildings, the pitched roof of a green house, and severalstreet lamps and trees. We addressed problems which are notencountered in traditional 2D representations such as negative obstacles, roughness, andslopes of non-flat environments. The viewpoint generation and evaluation procedure uti-lizes 3D ray-casting operations to account for the 3D structure of the environment. Weapplied a decision-theoretic framework which considers both the travel costs and theexpected information gain to efficiently guide the exploration process.

Simulation andreal-world experiments showed the effectiveness of our technique. Tovey C, Koenig S: Improved analysis of greedy mapping. Frontier-based exploration using multiple robots. Whaite P, Ferrie FP: An autonomous mobile robot with a 3D laser rangefinder for 3D exploration and digitalization of indoor environments.

Journal of Robotics andAutonomous Systems 45 Navigation strategies for exploring indoor environments. Journal of Robotics Research 21 Multi-level surface maps for outdoor terrain mapping andloop closing. Information gain-based exploration using rao-blackwellized particle filters.

Science and Systems RSS , Monte carlo localization in outdoor terrains usingmulti-level surface maps. In this paper we consider the problem of active mobile robot local-ization with range sensors in outdoor environments. In contrast to passive ap-proaches our approach actively selects the orientation of the laser range finder toimprove the localization results.

It applies a particle filter to estimate the full six-dimensional state of the robot. To represent the environment we utilize multi-levelsurface maps which allow the robot to represent vertical structures and multiplelevels. To efficiently calculate the optimal orientation for the range scanner, weapply a clustering operation on the particles and only evaluate potential orienta-tions based on these clusters.

Experimental results obtained with a mobile robotin an outdoor environment indicate that the active control of the range sensorleads to more efficient localization results. In such situations, a mobile robot typically has to estimate its position in theenvironment using its exteroceptive sensors and a map of the environment.

However,when a robot attempts to perceive its environment to localize itself, the choice of thedirection of the perception can substantially influence the accuracy of the position es-timate. An example situation is shown in Figure 1. In the left image, the range sensorof the robot is oriented parallel to the floor plane as in most robot scenarios with a 2Dsensor setup. This has the effect, that the vertical object shown in the image can notbe sensed by the robot. However, this vertical object might be crucial for localization,because it might allow the robot to reduce its uncertainty.

In contrast, the right imageshows a robot with a slightly different sensor orientation so that the vertical object canbe perceived. Accordingly, the robot can achieve a more accurate position estimate byactively orienting its sensor. This is why the technique is called active localization. Inthis paper, we consider the problem of active localization in outdoor environments bymatching laser range measurements to a given map of the environment. In a formerapproach [1], we already applied multi-level surface MLS maps [2] to model the en-vironment for passive localization with a fixed mounted laser range finder.

The MLSmaps can be regarded as an extension of the classical elevation maps [3,4,5,6] as theyadditionally represent intervals corresponding to vertical objects in the environment. Robot with the standard orientation of the range sensor where the robot is unable to sensethe vertical object left. In contrast to this the autonomously adapted sensor orientation allowsthe robot to sense the vertical object right.

A further advantage of MLS maps is that they can represent multiple levels. This isimportant when mobile robots are deployed, e. The paper is organized as follows. After discussing related work in the next section,we briefly describe the general Monte Carlo localization technique in Section 3. Thedetails of our active Monte Carlo localization are presented in Section 4. Finally, inSection 5, we present experimental results illustrating the advantages of applying activelocalization in outdoor environments.

In the past, this problemhas been adressed by several authors. For example, Kaelbling et al. The action selector chooses the action that minimizes the expected en-tropy after the next control action or maximizes the expected total reward, respectively. Jensfelt and Kristensen [9] applied multi-hypothesis localization to topological mapsfor active global localization. Davison and Kita [10] described a vision-based localiza-tion in which the robot actively senses the features based on visibiliy and informationgain. Recently, Porta et al. To use fine-grained grid maps and laser range finders, Fox et al.

Whereas their ap-proach is able to increase the efficiency of the localization by minimizing the expectedentropy, Markov localization has high computational demands. In contrast to the former approaches we focus on reducing the computational de-mands of the active localization.

The goal of this paper is to develop an active localiza-tion method which is able to deal with large outdoor environments. This probability is updated as follows: The terms to be described in Eqn. For the implementation of the described filtering scheme,we use a sample-based approach which is commonly known as Monte Carlo localiza-tion MCL [13].

Monte Carlo localization is a variant of particle filtering [14] whereeach particle x[i] corresponds to a possible robot pose and has an assigned weight w[i]. The belief update from Eqn. In the prediction step, we draw for each particle with weight w[i] a new particleaccording to w[i] and to the prediction model p xt ut1,xt1. In the correction step, a new observation zt is integrated. This is done by assigninga new weight w[i] to each particle according to the sensor model p zt xt.

The details of the particle filter implementation in combination with the MLS maps canbe found in our previous work [1]. To achieve this, we apply the greedy approach of Fox et al. Mythic consciousness, using propaganda vehicles such as the flag, early seized the attention of the "masses" and pointed the w a y to the disaster that ultimately befell the Germans and m a n y other nations.

This book is linted to the study of the documentary film in the so-called Third Reich. A number of works dealing with the Nazi feature film have already been published. Until now, however, there has been no monographic study of the documentary film as it relates to that other documentary medium, the newsreel. This work seeks to fill the gap and at the same time make a contribution to the history of the genre's popularity. This volume, a survey of the subject matter, aesthetics, and development of the documentary film and the newsreel under the Nazi regime, will be supplemented by two additional parts, currently in preparation, analyzing individual documentaries produced during the period The three volumes are arranged in such a w a y that the history of the Third Reich and the anatomy and face of the Nazi spirit can be reconstructed from the documentaries and newsreels of the period.

For this reason, some films were included to which little importance was attached at the time they were m a d e but which contain important details for a study of the Third Reich. Produced under a dictatorship that had redefined reality and was pledged to uphold the one and only truth propagated by the Fhrer, they are an integral part of the documentary film landscape.

W h e n artists forfeit their most important criteriontruthout of opportunism, fear, or fanaticism, they give up their independence. This aspect of cinematic art will be discussed as well. I have watched over three hundred documentaries and news-reels for this book and the two volumes to follow, and I have analyzed more than half of them in greater depth in volumes two xii Preface Preface xm N o t e s 1.

Adolf Hitler, Mein Kampf, 2 vols. Film im Dritten Reich Karlsruhe, , p. Paul Virilio, Die sthetik des Verschwindens Berlin, , p. Gerd Albrecht, Nationalsozialistische Filmpolitik Stuttgart, Erwin Leiser, Deutschland, erwache! I a m deeply grateful to the Bundes-Archiv in Koblenz, in particular to Peter Bucher and Anneliese Hoffmann-Thielen of the distribution department, for providing m e with copies.

I owe a special debt of gratitude to the director of the Deutsches Fi lmmuseum, Walter Schobert, and to Rainer Schang of the duplication department for their readiness to help during m y frequent visits to the cutting room, including weekends. I a m grateful to m y colleagues Gerd Albrecht and Eberhard Spie of the Deutsches Institut fr Filmkunde in Frankfurt a m Main for their advice and cormnents and especially for their readiness to help at any time in the procurement of documentary materials. M y thanks also go to Alain Lance for his comments. The efforts of Monika Zehe and Andrea Wlbing in the compilation of the bibliography also deserve mention.

I would like to thank m y friends Joachim Gaertner, Willi Khler, and Dieter Kramer for critically reviewing m y manuscript, and Gudrun Hasselbacher, Anita Jantzer, Edeltraud Kunze, and Elke Ringel for converting m y manuscript into a well-ordered final copy. The text is based in part on lectures and seminars I delivered in 1 9 8 5 , 1 9 8 6 , and at the Kunstwissenschaftliches Institut of Philipps-Universitt in Marburg and the Faculty of Fine Arts of the Uiuversity of Tel-Aviv.

Those who failed to recognize the [changed] times have no political or cultural or moral right to hoist another flag. The film industry is marked by a general lack of courage, a fear to stand up for one's belie, and a lack of enthusiasm to make commitments. The movie producers say "you can clean my plumage, but don't ruffle my feathers," mollifying themselves by hoisting a new flag.

Most probably some pennant from a bygone era. Intellectual liberalismwhich in reality means intellectual chaosis dead and buried. To argue that art has no bias Tendenz is foolish, naive, and absurd. Joseph Goebbels, 2 8 March i "Flags are wind m a d e visible," wrote Elias Canetti in Masse und Machti'- summing up the nature of flags in terms of two basic characteristics: Originally, though, flags a cultural history of flags, standards, and banners has yet to be written likely had a utilitarian function. Serving for the identification of friend or foe and as a rallying point during engagements between units or individual soldiers, flags afforded protection to those within a unit, ultimately ensuring their survival.

The fall of the flag of one's own a r m y meant that chaos would ensue, soldiers running heiter skelter across the battlefield or directly into the enemy's arms. Albrecht Altdorfer's monumental painting "Battle of Alexander at Issus" gives a sense of the vital importance of flags in the conduct of war. The various forces portrayed in this vast panorama of soldiers embroi led in the tumul tuous struggle between ancient Greeks and Persians are so intertwined that the different flags are virtually the only w a y for viewers to orient themselves.

It is probably impossible to determine in which spheres of life flags first came into use. What has come down to us is a report of the magnificent ceremony in which the first flag was formally consecrated when Charlemagne was crowned Holy Roman Emperor in the city of Rome. During war, in seafaring, and in the case of religion, flags were used chiefly as identification signs and as a means to highlight differences. During the crusades, which lasted two hundred years, the number of flags w a s myriad. They gave courage to the knights of one's own country w h o were obliged to fight on foreign soil, and they intimidated the natives.

Flags appeared as identification signs on the world's oceans long before Christians took to the sea. The Vikings used them during their sea voyages. With a raven the symbol of Odin, their god of w a r and death painted on their standards, the Vikings brought a reign of terror to the seas. And with martial insignia on the flags flying from their topmasts , Wil l iam the Conqueror ' s ships set sail from N o r m a n d y in to invade England at Sussex and defeat the forces of the successor to the throne, Harold II, at Hastings.

The Bayeux Tapestry, an embroidered frieze feet in length and a pr imary cultural and historical document, depicts the lovely cross-emblazoned flags that the Church had granted William in Rome. E v e n Richard Wagner was conversant with the role of flags as signals. In his opera Tristan and Isolde, set in the Middle Ages , he makes reference to them through the resonant baritone Symbolic Value of Flags and Standards of Tristan's faithful retainer Kurwenal , when Kurwenal Act I, Scene 4 informs Isolde, as they sail the Irish Sea, of the upcoming landing on "Cornwall's verdant strand": On the mast a flag is flying.

And gaily waves toward the land And in King Mark's castle They know the bride is at hand. Nevertheless the pr imary function of the flag is not to act as a pledge of good for-time but as a symbol of one's own troops that, when captured, lost sight of, or gone unnoticed, inevitably signals a battle's end, or death.

Unity under the flag exists only so long as deserting the flag poses a threat. This negative function of the flag makes it an instrument of repression within the ranks, not the sign of hope that state-controlled propaganda would suggest. A flag fluttering in the breeze is a symbol of life in the midst of the general threat of death. In other words , it is an ideal instrum e n t for controll ing the masses. The dialectic between the promise of good fortune and the risk of death moves the flag into the realm of religion, which helps to explain the use of flags in religious worship.

They m a y appear in the form of the three-tail Easter flag representing the resurrection of Christ or the multi-colored p r a y e r flags found in Tibetan monaster ies or the mag ic streamers carried by American Indians, but they are always intimately associated with the supernatural and with the notion of eternal damnation for those who "fear not God. A s an object of religious veneration, the faithful considered the flag to be divinely inspired, i. The flag only assumed its symbolic function in the wake of the secularization that accompanied the Enlightenment.

Abstract internalized values now gave meaning to life, providing a substitute for religious transcendence. Eugene Delacroix's famous painting "Liberty Leading the People," in which the allegory of Revolutiona w o m a n with bared breast holding a tricolor and a muzzle-loaderleads a band of fighting m e n onto the stage of history, gives artistic expression to this change. The flag is no longer borne by a soldier but by an abstract The Triumph of Propaganda Symbolic Value of Flags and Standards allegorical figure, thereby elevating the significance of the scene beyond the actual battle depicted to a higher plane of values.

The flag's transformation from rallying point to revolutionary symbol w a s rooted in technological change. Since the technological revolution of the nineteeth century, w a r w a s no longer a duel between individual soldiers. It was now conducted by mechanical weapons that delivered death and destruction over immense distances.

W h e n a soldier was dying or being killed, he no longer looked into the whites of his enemy's eyes; all he saw w a s the muzzle flash of a gun. The only contact between combatants w a s that between the telescopic sights of their artillery pieces. This kind of warfare invalidated the flag's role as a true identification sign. Paul Virilio has called modern warfare the "war of light," a mechanized scenario in which target acquisition, "observation," is more important than firepower.

In other words, it is primarily percept ion a n d observat ion that decide the o u t c o m e of a war; weapons are of secondary importance. In this kind of w a r scenario it is no longer a question of eliminating the object of perception, the raised flag of medieval warfare. Rather, it is a question of perception itself. The apotheosis of this w a r is the nuclear flash, where the weapon and the flash of light combine to blind and annihilate the e n e m y t h e c o n s u m m a t i o n and logical consequence of the idea of "blitzkrieg" [lightning or lighting war, to use Virilio's play on wordsTransl.

In this twentieth century scenario the flag has no practical use in affording protection. On the contrary, the nerve center of an armyits "flagship"is the most likely target for destruction. In modern warfare, deserting the flag seems to offer the only true chance of survival. Nevertheless, the myth of victory and the flag as the symbol of victory persist to this day. As a symbol of the nation, the flag is still considered inviolable. Insulting it is subject to severe punishment under the law. On days of national mourning it stands at half-staff.

At state funerals it is draped over the coffin to show that the deceased has been accepted into the immortal community of the nation. It is a symbol that is understood throughout the world like no other. As he lies dying, a young sapper places a flag under his body so that the liberated citizens of Odessa will later find it, drenched in his blood, and w a v e it as a sign of victory.

This is a desperate attempt to give meaning to "death in battle" in a world devoid of religious transcendence w h e r e the "greater good"the nationcalls for unquestioning obedience under the sign of the flag. In this sense, the words of Elias Canetti cited at the beginning of this section have a numinous and magical aspect that I will relate below to the imperialist and militarist function of the flag.

Flags "are like bits cut from clouds, nearer and more varied in color, tethered and given permanent shape. In their movement they are truly striking. Nations use them to mark the air above them as their own, as though the wind could be partitioned. Countless blood witnesses are with us in spirit. They m a y be associated with festivities, prayers, and fimerals. F lagsas simple as they are effectivehave had an importance in history that has been worth fighting for and waging war over.

Flags by themselves are impartial though even a plain white flag has a special meaning ; and the symbols used in flags are often nothing more than utilitarian. There are whole books written for future sea captains and pilots that are devoted to explaining the shape, color, and positioning of the various naval flags. Seamen introduced the concept of "flagging" at the beginning of the modern era as a w a y of differentiating the display of naval flags from that of other types.

The English have employed naval flags since In the German-speaking states their use dates back to when pilots in the Baltic adopted the term "flagging" to describe the messages conveyed by means of flags. The complex process of ship-to-ship and ship-to-shore c o m m u nication gradually gave rise to the development of a sophisticated The Triumph of Propaganda a n d s tandardized flag "language" for the purpose of keeping ships at sea out of harm's way.

A discussion of the makeup of flags becomes a volatile topic whenever w e talk about symbols that represent a political ideology or regime. The first documented reference to German flag customs and etiquette dates back to the eighteenth century. The dozens upon dozens of small German states dressed their ships with masthead flags in the livery colors of their respective rulers.

After the black-red-gold flag waved from the masts of Germ a n ships. However , it w a s not recognized universally on the seven seas as a symbol of sovereignty. The British government, in fact, delivered a formal note to the German Confederation stating that Britain would view the Confederation's ships as pirates if they sailed into British waters without flying the sovereign flag of the respective federation member.

In "Dreaming of a Fleet" Ferdinand Freiligrath, Germany's poet of freedom, symbolized the unification of these numerous small states into a single nation-state as black-red-gold s torm clouds garlanded across the world's oceans: Wave now free Black Red and Gold from every mast And flag pole ringing the land! The ocean has festooned itself In thousands of pennants, oh flag once reviled. Bismarck decreed it w a s to be the Black-White-Red, because this combination of colors "represented not only the black and white of Prussia but the red and white of the Hansa cities and Holstein, i.

The flag flies in the face of the enemies who threaten it. Who hate its colors. It waves back and forth in the wind along the side of the ship, and far from the beloved Fatherland upon storm-tossed seas. We pledge our loyalty to it. We dedicate our life to the flag, to the Black and White and Red. Symbolic Value of Flags and Standards Beginning in the landlocked Austrian monarchy dressed its ships with red-white-red mas thead flags bearing an open crown as the emblem of regal power. The enormous impact of the black-white-red flag even on Germ a n s living outside of G e r m a n y is reflected in this rapturous description written by Gustav Freytag and published in the journal Die Grenzboten in Aha, fluttering, billowing, a flash of color!

Hurrah, you Black and Red and Gold! It's the former imperial standard. Those are the ancient colors! This is the banner under which we'll fight and Obtain fresh scars. You see, we've just begun The final battle is yet to come! It was only after I had explained this to old Kaiser Wilhelm that he accepted the adoption of the new colors.

It w a s Ltzow's legendary free corps, organized within the Prussian army, that gave birth to the idea of "unifying Germany by force of arms. In his well-researched study titled Die deutschen Farben , Paul Wentzcke devoted more than sixty pages to the debates that raged over the question of the new flag from the end of the nineteenth to the begirming of the twentieth century. His discussion illuminates the age-old dichotomy between symbol and reality and indicates the depth of ill-feeling that forms part of the genealogy of the Germ a n flag.

Hitler wanted his new swastika flag to lead the nation a w a y from the discord of party politics and regional interests as they related to the question of the flag and to stand as an affirmation of the unity of the German fatherland. In 1 8 7 0 Chancel lor Bismarck put an end to the farce with a touch of sarcasm: I wouldn't care if it was green, yellow and purple, or the flag of Mecklenburg-Strelitz.

But the Prussian soldier simply wants no part of the Black, Red, and Gold. A reenactment of the cerem o n y formed the dramatic high point of the second part of Ernst Wendt's silent movie Bismarck the quintessential German film. The const i tut ion that w a s ratified that same year m a d e Black-White-Red the official colors of the w a r ensign and the merchant flag, so that "the black-white-red tricolor now flew over the fortresses of Paris and the palace of Versailles.

Given the popular in the words of Golo Marm published the following announcement in the Reich L a w Gazette of 12 November In the upper left-hand comer the canton shall bear the imperial coat-of-arms on a rectangular field The imperial coat-of-arms consists of a double-headed eagle displayed sable on a gold field, langued gules, gold-beaked, and taloned. The young Otto von Bismarck, a delegate to the Diet of the reconstituted G e r m a n Confederation, quickly dissociated himself from the colors and their symbolic meaning at the parliament of the Erfurt Union in Black-Red-Gold, he said, had never been the imperial colors; they were symbols of rebellion and the barricade.

Those were the Prussians, their colors black and white.

The Triumph of Propaganda: Film and National Socialism, 1933-1945

Their flag streaming before them once again. As the king's loyal men lay down their lives for him. For their king, each one cheering. As we watched them carry their dead away Without so much as a whimper, A shout pierced their loyal hearts. You are Prussians no longeryou are Germans now. Black-Red-Gold is ablaze in the sunlight. The desecrated imperial eagle falls; This is the end of your glorious history, HohenzoUems, This is where a king fell, though not in battle. We take no pleasure In watching a falling star You'll regret what you did.

Prince [Bismarck], None there are who are more loyal than Prussians. The flag was not only a support for soldiers in uncertain times; it w a s also ideally suited for subjugating the individual to its symbolic power. This alliance of emotions would unite academics and workers , soldiers and housewives. After millions of soldiers had died fighting under the Black-White-Red in the First World War and after the unification of Germ a n y under the same flag"which is still regarded as a great national treasure" MP Dr. Kahl the constitutional committee, following months of tedious deliberation, decided in a roll call vote on 4 June to adopt the Black, Red, and Gold.

The decision w a s taken in part to ward off the "threat" posed by the Independent Socialists' at tempt to force the adoption of "their red Soviet flag. At any rate, the colors Black, Red, and Gold gave rise to a symbiotic love-hate relationship that created the conditions in which the defeated parties could cultivate the idea of taking revenge.

The Social Democratic Interior Minister Eduard David called the "tricolor" the "symbol of a sense of national community" and recommended "maintaining Greater German unity as a lofty ideal and future goal. Under the Weimar republic the old new colors met with disapproval , especially from right-wing groups such as the veterans' organization called the Stahlhelm. They felt that the colors were a concession to the Social Democrats from whose ranks Reich President Ebert had come. In the eyes of the right, the Black, Red, and Gold stood for a defenseless democracy. They were the colors Symbolic Value of Flags and Standards 11 of the unrestra ined violence of the Revolut ion of ; a n d which w a s of central importance in the rise of fascismBlack-Red-Gold became the symbol of the "humiliation of Versailles.

For them, the flag of the Weimar republic became an onmipresent aggravation and a constant goad to erase Germany's "shame. The decision of the National Assembly gave the opposition on the right a symbol that in future would arouse all its demonic instincts. It reflected the strife that existed within the fledgling democracy. A s history has taught us, the disputes over the national colors and their symbolic meaning was an intermezzo that ended tragically. Hitler used the debate between the proponents of the Black-White-Red and the supporters of the black-red-gold flag to incite the masses that would soon rally around him.

T h e F l a g P l e d g e We young people will carry the flag to the front as the young prepare to attack. May it arise and ascend and shoot like a flame into the sky I YJe've sworn an oath to the flag for ever and for all time to cornel Damned he he who desecrates the flag! The flag is our faith in God and people and country! Rob us of life and limb, if rob us you must, but don't take our flag. We cherish the flag as dearly as we do our mothers.

For the flag is our tomorrow, our honor, and our courage. Eberhard Wolfgang Mller, W h e n soldiers swore the oath of allegiance to the flag, the flag attained the status of a sacred shrine. The flag pledge assumed the function of a religious rite sanctioned by a priest. Enticed by the "magic implicit in the pledge" Peter Dade , untold millions of soldiers have marched to their death throughout history.

In mercenary armies the flag pledge was rendered to the commander in 12 The Triumph of Propaganda chief as a symbolic seal on a hireling's contract. The custom of touching the flag while rendering a pledge did not come into prac tice until the seventeenth century. The question of rendering an o a t h of allegiance to the state and the military has been an issue of controversy in Germany for centuries.

In the members of the German Confederation agreed that the military should not be forced also to swear an oath to the constitution. The Reich Constitution of , however, did require that an oath to the constitution become part of the flag pledge. Then after the Franco-Pruss ian W a r 1 8 7 0 - 7 1 the flag pledge became strictly an oath of loyalty to the Emperor as Supreme War Lord.

Following World War II the political component was watered down and the flag pledge divided into a military loyalty oath and a specially devised pledge of allegiance to the constitution. After the death of Reich President Paul von Hindenburg, the Naz i s enacted a law on 2 0 A u g u s t transforming the flag pledge into an oath of personal loyalty to the Fhrer: The SSthe m e n with the Death's H e a d insignia on their capswere a vo lunteer force before the war that pledged, if need be, to die for Hitler "with faith in their hearts. Yes, the flag m e a n s more than death" w a s the marching song of the Hitler Youth.

In the Prusso-German armies a n d most especially in Hitler's army, defending the flag, even to the point of sacrificing one's life, w a s considered the ultimate duty imposed on a soldier by his oath of loyalty. Surrendering the flag w a s tantamount to losing one's honor and brought shame upon the entire regiment. W h e n a unit lost its standard, it lost its soul. On the other hand, a soldier w h o. Symbolic Value of Flags and Standards 13 captured an e n e m y standard had pernussion to use his heroic deed as proof of his martial prowess.

It was d r u m m e d into the head of every member of the Hitler Youth during encampments and field exercises that the loss of even a pennant produced the wors t possible stain on one's character. The only song included in the official publication Pimpf im Dienstrequired reading for the German Jungvolk [the group between the ages of ten and fourteen in the Hitler YouthTransL]was dedicated to the flag: Let those desperadoes lead the charge, we'll follow in close order formation. Songs sung together under the flag heightened the sense of fellowship.

Psychologists teach us how easy it is to fill an emotional v a c u u m by forming a powerful affective bond with a leadership figure or a fetish flag. Refusing to identify with the Weimar republic as their country, many people felt a similar void within themselvesuntil Hitler offered them a new w a y of bondinghis way. After relinquishing his individuality, the Nazi Party member was vulnerable to every suggestion put forward by the person "who robbed him of his conscious personality" Sigmund Freud. Professional soldiers and conscripts in the Bundeswehr today no longer swear an oath to an individual or an office.

Rather, they render a pledge to the state and the people: The oath sworn by soldiers of the former German Democratic Republic's Nationale Volksarmee was similar to that of the Bundeswehr: Should I ever violate this m y solemn pledge to the flag, m a y I suffer the harsh punishment provided by the laws of our Republic and be s p u m e d by the working class. Down below, starting at the far end of the Sportpalast, the standards representing Berlin, followed by hundreds of Party flags from Berlin, are moving forward.

Little by little the flags are coming up out of the basement vault of the Sportpalast. To the sound of "Deutschland, Deutschland ber alles" the flags are borne through the immense hall. The flags are coming closer and closer, the lead flag has just reached the gallery. At the back of the gigantic hall a section has been left unoccupied for the march-past of the flags. The four standards are just beginning to move up to the podium. The flags are moving to the rear, the end section of the hall. Flag after flag keeps coming up out of the basement vault.

Every side corridor is packed with bright red swastika flags. The audience throughout the entire Sportpalast has stood up and, with arm raised in the Hitler salute, has joined in the singing of the national anthem. Its earliest recorded use dates back to the Indus civilization around B. Apparently persuaded by what he considered to be the symbolic power of the swastika, the Hindu monk Agehananda Bharatis openly expressed his adnuration for Hitler in a "forum" held at the Frankfurt Book Fair, which had chosen India as its theme that year.

Not thinking of the inhumanity that the concept of the master race symbolized to nations forced to live under colonial rule, he claimed that the mass of India's people held views that were very different from those shared by the westernized Indian elite. Hitler, he said, w a s an "avatar," a deity that had descended to the earth in incarnate form. The swastika, the Indian symbol of salvation, steeped in tradition, had sanctified his mythic mission.

Symbolic Value of Flags and Standards 15 means "great good luck"; in Greece it was called hemera and w a s the symbol of the sun. The swastika has taken on a number of meanings over time: Thor's hammer, a sun wheel, a wolf trap, a mill wheel. In the twentieth century Kerensky's provisional government in Russia used the swastika on its bank notes as a symbol of independence.

Wilhelm Reich in his Die Massenpsychologie des Faschismus Mass Psychology of Fascism, added yet another facet to the symbolism of the swastika: In his interpretation of the swastika as a sexual symbol, Reich relied on the representation of a swastika discovered by Bilman and Pegerot dating back to Indo-Germanic times and containing the following inscription: Grow great in the embrace of God, fruitful to nourish mankind. Interviews with people of various backgrounds and of either sex showed "that very few people fail to recognize the meaning of the swastika.

Reich did not, however, feel that this aspect of the swastika's effect on unconscious emotionality accounted for the success of Hitler's mass propaganda; it was "merely" a "powerful aid. Various anti-Semitic organizations and Free Corps units soon used the swastika on their battle standards. The swastika became a symbol of reactionary opinion and a sign of race identity directed against Jews and Gypsies, Marxists and intellectuals, the mentally ill and pacifistsagainst all the outsiders w h o m Marcel Proust had labeled "la race maudite.

In his thoughts on "our flagour p r o g r a m " in his book Mein KampfHitler wrote in that he saw in red the social idea of the m o v e m e n t and in the white disk the national component. In the black swastika he saw "the mission of the struggle for the v ictory of the A r y a n man, and, by the same token, the victory of the idea of creative work, which as such always has been and a lways will be anti-Semitic. T w o y e a r s later he a lso designed the Party standard. A s a "special symbol of victory" he included it "among the symbols and battle signs of the National Socialist struggle.

Manfred von Killinger stressed this idea of continuity in Mnner und Mchte: Although the black, white, and red flag under which he had fought in the war"these uniquely beautiful colors, in their fresh, youthful combination"was "sacred and beloved" to him, he was nevertheless adamantly opposed to letting it stand "as a symbol for the struggle for the future. Thus, on 10 March , the Day of National Mourning, government offices flew only flags with the black, white, and red colors of Prussia.

Just two days later, however, Hindenburg relented and issued a decree on the flag ordering that "until a final sett lement is Symbolic Value of Flags and Standards 17 reached regarding the national colors" the black-white-red flag and the swastika flag were to be flown side by side. The decree stated that the traditional symbol represented "the glorious past of the G e r m a n Reich," while the new flag stood for "the mighty rebirth of the German nation": Reichstag president H e r m a n n Goring desired "a true symbol of the race.

National Socialism attracted to itself whatever resources of iron and steel the German people had within themselves. Similarly, it was our battle standard under which these fighters were assembled, under which they struggled, fought, and, in many cases, died. We must not forget that at decisive moments it was this battle standard that time and again made the weak strong. We must not forget that so long as our Fhrer held our battle standardthe swastika [flag] with its glorious ancient colorsin his grip, he also held the destiny of the German people in his hands. The swastika has become a sacred symbol for usthe symbol around which all our hopes and dreams revolve, under which we have endured suffermg, under which we have fought, sacrificed, and ultimately, for the benefit of the German people, triumphed.

The day before, on 15 September , Hitler issued an order making the swastika flag Germany's official national flag. W h e n he presented the armed forces with their new battle standard, the w a r ensign, he did not neglect to use the Iron Cross insignia on the swastika flag as an occasion to hark back to the traditions of the World War I Imperial Army: May the Swastika be a symbol for you of the unity and purity of the. You are under an obligation to the black-white-red colors of the Reich to perform your duty loyally while you live and while you die.

Though there w a s no victor in this senseless and destructive encounter between the British and G e r m a n fleets, m a n y sailors were killed in action. A painting of a sinking cruiser, tifled "Skagerrak," w a s the focal point of the Berlin Art Exhibition. It showed a sailor proudly holding up the flag: The swastika that Hitler called "a token of freedom" would soon become a symbol of s lavery for all Europe. The flag w a s omnipresent in the Third Reichon the streets, flying from houses, in documentaries and newsreels.

The flag had, as it were , gotten into the blood of the Germans. The swastika flag w a s meant to communicate all the virtues a n d sjmibolic values of the Nazi movement. The blood-red flag with the mystical swastika emblazoned on a pure white circle w a s like no other with regard to its manifold symbolic meanings. It represented all the amorphous ideas and second-rate virtues in the Nazi catechism: The flag w a s also a sign of the Nazi ideology's irreconcilable hatreds: The swastika flag reflected many of the irrational beliefs that were foisted on millions of Germans through the multipher-effect of the weekly newsreels and Party congress films.

Riefenstahl liked to show the flag blowing in the wind, as a sign of Symbohc Value of Flags and Standards 19 movement: The fluttering flag had, of course, already been employed earlier as a symbol of change and freedom, of the resolve to achieve victory. The Nazis exploited it for their own purposes: We are the army of the Swastika, Raise the red banners high. For the German worker The way to freedom we shall pave. The Nazis m a d e skillful use of the emotional content of left-wing revolutionary songs to create their own melodies for the march "into eternity"with different lyrics, of course.

Roland Barthes in his book Mythologies presented the following graphic example of the symbolic significance of the national flag as an illustration of his theory of semiology: On the cover, a young Black in a French uniform is saluting, with his eyes uplifted, probably fixed on a fold of the tricolor. All of this is the meaning of the picture. But whether naively or not, I see very well what it signifies to me: Nazi myth-making worked in a similar fashionalbeit with one fundamental difference. Whereas the tricolor is apparently an unknown nationalist quantity to the African, a sacred myth lacking "flesh and blood," to the average Nazi Party member the swastika flag was equated directly with the Fhrer w h o was, as it were, present in every fold.

The myth of the nation w a s not an abstraction; it w a s palpably present in words and in pictures. It was not beyond the masses' comprehension. The flag was Hitler's ubiquitous deputy. Identifying with the flag was synonymous to identifying with the Fhrer. Naz i p r o p a g a n d a w a s largely effective because it succeeded in identifying the masses with the Hitler myth.

And it was to Leni Riefenstahl that Nazi propaganda owed a debt of gratitude for developing a workable aesthetic formula to elevate the mundane into an apotheosis of the nation. Even when a squad of troopers marched down the street carrying a single flag, passers-by were obliged to honor it by giving the Nazi salute. We will be true till death to that!

At the beginning and end of school holidays, students and teachers had to stand in line for inspection in the schoolyard as the flag w a s being raised and the Horst Wessel song sung. Starting at an early age, young people were forced to internalize the values represented by the flag: At the beginning of school following the end of vacation and at the end of the term before the begiiming of the school holiday, the flag must be honored in front of the entire student body, by in the first case raising and in the second lowering the Reich flags while one one verse from "Deutschland, Deutschland ber alles" and one from the Horst Wessel song are sung.

Before the introduction of the Youth Service Ordinance, schools with a 90 percent membership rate in the Jungvolk, the Hitler Youth or the corresponding girls' organizations, received a Hitler Youth flag. The voice that gives them their orders Is their enemy's voice and The man who speaks of the enemy Is the enemy himself Bertolt Brecht German War Primer 1 9 3 6 - 1 9 3 8 3 2 The association of the flag with blood can create a powerful symbol. Ernest , Duke of Bavaria in Friedrich Hebbel's play Agnes Bernauer creates just such a symbol when, in a thundering monologue, he invokes not the flag of peace, but the banner of war: Symbolic Value of Flags and Standards 21 "Look at this barmer It is woven from the same thread as m a d e the doublet of the last rider w h o follows it; and one day it will fall apart and turn to dust before the wind in the same fashion!

But the German folk has triumphed under it in a thousand baffles, and therefore only a cur can pluck it to pieces, only a fool try to patch it, instead of shedding his blood for it and keeping every shred of it'holy! The concept dated back to the days of the Hohenstaufen dynasty. According to the account in the Song of the Nibelungs, the Burgundians set out from the Rhine along ancient military roads and marched south by w a y of the Danube under a "blood banner. The "fiery banner" m a d e of red silk w a s a shared symbol valid for all.

The blood flag was thus an important symbol in public law. Having been granted the right to exercise high justice, the recipient of a fief was pledged under ancient Germanic law to render unswerving fealty to the lord from w h o m "justice" was held and to perform unlimited military service on his behalf.

Originally, kings alone had the privilege of granting justice. The Nazis invested the concept of the "blood flag" with a decidedly emotional coloration. Henceforth, the new standards and flags of the N S D A P and its associated organizations would be consecrated by being ceremoniously touched with the blood flagalways in the presence of a sworn witness to the Hitler Putsch. We are building the eternal Feldhermhallen of the Reich, The steps leading into eternity. Until the hammers drop from our hands. Then wall us into the breast of these altars.

It w a s a square containing a large swastika of the cotised and upright variety within a golden Wr'eafli and displaying golden eagles in the cantons: It did not w a v e or flutter, since it w a s made of stiffened linen and w a s similar to a panel painting or, more properly, an icon. The standard was an adaptation of the Roman vexilla. Since the second half of the first millennium, this phrase has been the title of a h y m n to the Holy Cross written by the most famous Latin poet in Merovingian Gaul, Venantius Fortunatus. Until , it w a s regularly sung in Good Friday processions; it lives on universally in the recitation of the Divine Office.

Symbolic Value of Flags and Standards 23 The personal standard was a sign of the Fhrer's physical presence. Ord inary flags sufficed to demons tra te his mere ly metaphorical omnipresence; they carried the semantic image of the Fhrerto the point of fiction. In this w a y the actual power of government has been duplicatedin the person of the 'Fhrer' standing at its head and in a notional leader w h o fits in neatly with Hitier's political decisions and the coercive measures at his disposal to enforce them.

He's a member of the Prince Henry Regiment and is clutching the regimental colors. His eyes seek out the king and speak without talking: I've held on to the flag you entrusted me with, but I'm at the end of my tether. Frederick bends low over him. Gently but firmly he wrests the barmer from the man's grip. The standard bearer looks into the face of the kiag, then collapses without making a sound. The king sits up straight in his saddle, swings the flag up over his head, and calls out amidst the tiimult of battle and the shouts of pain: Those of you who are brave soldiers, follow me! He moimts his horse.

Beaten but tinbowed, he turns to his hussars and speaks: Brave is he who stands the test, and victory goes only to the brave. With the flag and for the flag. The flag was used as a metaphorical instrument to generate confidence of victory. It is impossible to overrate the part played by the first dead man in the kindling of wars.

Rulers w h o want to unleash w a r know very well that they must procure or invent a first victim.. Nothing matters except his death; and it must be believed that the enemy is responsible for this. Every possible cause of his death is suppressed except one: Its spirit changes into that of a war pack. Hitler's annual consecration of the flag w a s the high point of every Party Day. The ceremony, which Leni Riefenstahl extolled in her films Sieg des Glaubens and Triumph des Willens, was always accompanied by the singing of the Horst Wessel song: Hold high the banner!

Close the ranks hard serried! The Storm Troops march with cabn and steady pace. Comrades killed by Red Front and Reaction are buried. But in spirit keep their place. In his b iography of Hitler, Joachim C. Fest emphasizes Hitler's "talents as stage manager," which reached their c l imax when the movement ' s celebrations of death created a m o o d of hypnotic fascination a m o n g the masses: In scenes such as these out of a Good Fr iday ce lebrat ionscenes , as w a s said of Richard Wagner ' s music, in which magnificence w a s used to sell deathHitler's idea of aesthetic politics matches the concept.

The three martyrs who comprised the Nazi triumvirate of death were all young heroes, the myths surrounding them well suited to the production of uniquely captivating propaganda. Unvanquished until death, they were transfigured into supernatural beings and lived on in the m e d i u m of film: Thus, he said, the young doomed hero was surrounded by a nimbus of complex emotions: In Hitler's war films the flag served as a symbolic relief from the landscape of war and, more rarely, as a shroud.

Contemporaries folded this paradox into the seemingly cynical observation that "after a few marvelous words by Baldur von Schirach [head of the Nazi youth movementTransl. One for all and all for one: Bondage has an end! Let wave, let wave, whatever can. Standard and banner wave! Here will we purpose, man for man. To grace a hero's grave. Advance, ye brave ranks, hardily Your banners wave on high; We'll gain freedom's victory. Or freedom's death we'll die!

Illustrierter Film-Kurier ended its review of Morgenrot in the following inflated terms: Losses have to be borne andeven fifty years of night can't blind a German! Even if w e must die! We all understood that the word 'art' Kunst comes from the w o r d 'can' knnen , that not everyone can do what he wants to do. The general line must be viewed in this context insofar as it is not directly related to presenting the events of the day, that is, as I have said elsewhere, w e don't want to see our Storm Troopers marching across the screen or the stage.

Their job is to march in the streets. This is but one means of giving expression to political life, and this form of expression will be used when it is artistically imperative to do so or, alternatively, when one cannot think of anything better. For as everyone knows, this is the easy w a y out.

TEST SERIES FOR PRE-2016-Geography-1

Lacking greater skill, people feel obliged to use National Socialist symbols to demonstrate the strength of their convictions. Song of the Young Socialist Workers in the early s "We filmed a demonstration. The color red came out black in the film. It would have been better to use green flags to get the right shade for red. Our demonstratorsreal proletarians from Wedding [a working class district in BerlinTransl.

So we had to come up with a different solution. The demonstrat ion he referred to is one of the most impressive scenes in the film. It is not difficult to find additional examples of the red flag in leftist films. In Brder Brothers , a Social Democrat ic film that deals with a strike by H a m b u r g dockworkers, the flag forms part of the final apotheosis, appearing to the incarcerated workers through prison walls.

A r t and kitsch, s imple s tra ightforward symbol i sm and phony emotionalism, were not far removed from each other in scenes such as these. To be sure, it is as w r o n g here as it is in other instances to speak in pejorative terms about the superficial parallels between Naz i symbol s a n d those used by the labor m o v e m e n t. E v e n when w e quantify the use of identical symbols or compare the results with parallels in other areas, w e still find that the most important sources of the symbols used by the Nazis were military and nationalist conservative groups.

The reason for this w a s not simply that these things were relatively public, susceptible to corruption or reinterpretation which prompted Hanns Eisler's fruitful but by no means convincing attempts to invent an incorruptible musical language. There w a s another equally important reason. In order to be politically successful and maintain the goodwill of their financial backers in big business, the Nazis had to neutralize the political power of important segments of the working class or win them over to their side.

It w a s not enough to terrorize the labor movement or, after , to crush it. Rather, they mobil ized their entire ideological apparatusfrom the d e m a gogic linkage of crucial concepts , as, for example , in "National Socialist German Workers' Party," to the exploitation of signs and symbols , including the flag.

Flags clearly played a significant role in the history of the labor movement. But how did a piece of colored cloth acquire such 28 The Triumph of Propaganda importance? Scholarly research evaded this question for quite some time after The German public also dissociated itself from the issue by choosing, as it were, to repress it.

The result, as so often in the past, w a s that they drew upon conservative myths or mystical and irrational explanations. Today, however, there are signs of an attempt to arrive at an understanding of the issue that goes beyond mere ideological criticism. Historical symbol research and social historical analyses of symbols can bring us closer to an understanding of that need for sjnnbols which Robert Michels long ago perceived in the labor movement.

Today it is chiefly advert is ing and the omnipresence of its essentially frivolous but highly developed imagery that are continual reminders of the effect of i conographic symbol ism. Strangely, postmodern trendsetters incorporate these empty m a n nerist symbols into their Rococo-like culture. There is in all human beings a considerable "number of affective factors that go to make up experience. In fact, there is greater peril if w e close our eyes to these phenomena. In the past, greater importance w a s attached to the subtle meanings in the written and spoken language used in the labor movement.

N o w it would seem appropriate to give increased attention to sensory and symbolic forms of orientation. One of the most important symbols in the labor movement is the red flag which appeared on everything from the logo of the K F D Corrununist Party of Germany newspaper during the Weimar republic to the barmers carried in the strikes of the s.

Hilmar Hoffmann-The Triumph of Propaganda Film and National Socialism, 1933-1945(1997)

The history of the red flag is closely tied to the social history of the past two hundred years, and it is also important as an example of the Symbolic Value of Flags and Standards 29 supreme confidence with which workers have dealt with the legacy of the national culture and the culture of the ruling class.

Viewed from the perspective of political revolution, the early history of the red flag provides sporadic examples of its appearance during peasant uprisings. The red flag led the w a y to victory for the bourgeoisie during the French Revolution of At the court of Charlemagne the flag w a s cons idered "the sacred symbol of suzerainty" and henceforth became a symbol which the emperor used when he granted the right to exercise "high justice" and pronounce sentence of death Blutbann.

According to Wendel's interpretation more programmat ic than analytical , it represented the "affirmation of a social order that was founded on a free people free to work in its o w n behalf. In the red flag became an identification sign and a symbol that provoked protest in both France and Germany at the same time. Henceforth, it became the symbol of the "Red Republic," of the socialist and communist movement.

Prior to that time, around , it had appeared only sporadical lyperhaps more by chanceduring a riot of textile workers in Aachen and the revolt of the Silesian weavers in In the s u m m e r of workers brought out the red flag during demonstrations, on barricades, a t political parades , etc.

Oftenfor example, in May in Wuppertalthe red flag appeared beside the black-red-gold tricolor as a sign of the continuing rivalry between workers and the bourgeoisie. According to an anecdote, Friedrich Engels was supposed to have been responsible for making sure at night that there were enough red flags in Wuppertal for m a x i m u m visual effect the next day.

Consequently, the red flag became a symbol in the chaotic year that both accompanied protesters and set them apartover and above any possible inherent properties of the color: Thus red acquires historical significance only as a result of political conflict, of its establishment as the symbolic color of the socialist 30 The Triumph of Propaganda and communist workers' political movement. Its symbolic meaning does not derive from an emotional association with aggression that, like a genetic trait, is inherent in the color itself, as suggested by the symbol theory of Otto Koenig.

Rather, the "aggressive element" in the color red as in the expressive properties of any color is the result of its historical and cultural development. The formulation of a proletarian response to prevailing public opinion called for different forms of sensory orientation and commimi-cation from those used at political gatherings or discussions in workers' clubs.

The red flag was of great importance in the process of developing a public identity. It gave coherence to political demonstrations and laid out limits with regard to other goals and strategies. To quote Georg Simmel, it acted as both a "cause and effect of cohesion. After the practice of planting flags in the highest possible and most inaccessible locations w a s one of the most popular rituals in the proscribed labor movement.

During the Nazi era such exercises were also a frequent occurrence. They were always accompanied by a feeling of pride that only workers were capable of mustering the strength, dexterity, and imagination to perform such feats. The same w a s true of the "tableaux vivants" whose techniques were especially in keeping with the "condition ouvriere.

Initially, symbols are neutralit is only the part they play in history and ideology that changes them into signs of liberation or of total i tarianism. Democrat ic states also have their symbols. W h a t w a s significant a n d historically catastrophic about the Nazis ' debasement of flag symbolism was that it responded to latent revanchis t and total i tarian fantasies and needs. In this Symbolic Value of Flags and Standards 31 regard, flag symbolism cannot be viewed in isolation; it must be understood within the context of fascist propaganda.

The aesthet ic of the Nazi m o v e m e n t that encompassed all spheres of public communication and culminated in the films of Leni Riefenstahl had a single objective and a single method: This aesthetic depicted the collective, the crowd, in ever new and rigorous forms of art, shifting and channeling it into a movement that was to lead the w a y out of the narrow confines of bourgeois life toward noble and all-embracing goals aimed at achieving a glorious future. It thus channeled the dreams of power and revenge harbored by the humiliated German soldiers who returned from the First World War, realizing that they had been cheated out of their youth, their health, and their lives.

They acquired a sense of security in a movement in which they felt themselves to be part of a rising tide that gave new meaning, new direction, new incentives to men who were living in the past, fixated on their wart ime experiences. Rather, the m e d i u m w a s the message. It completely subordinated the individual to the collective and gave the moviegoer, the radio listener, the reader, and the partic ipant in Nazi m a s s rallies a sense of power, of being one with the collective.

In this state of intoxication, the meaning or content of ideas was no longer important.