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Item Lightness Perception in Tone Reproduction for High Dynamic Range Images(The Eurographics Association and Blackwell Publishing, Inc, 2005) Krawczyk, Grzegorz; Myszkowski, Karol; Seidel, Hans-PeterItem Efficient and Robust Annotation of Motion Capture Data(ACM SIGGRAPH / Eurographics Association, 2009) Müller, Meinard; Baak, Andreas; Seidel, Hans-Peter; Eitan Grinspun and Jessica HodginsIn view of increasing collections of available 3D motion capture (mocap) data, the task of automatically annotating large sets of unstructured motion data is gaining in importance. In this paper, we present an efficient approach to label mocap data according to a given set of motion categories or classes, each specified by a suitable set of positive example motions. For each class, we derive a motion template that captures the consistent and variable aspects of a motion class in an explicit matrix representation. We then present a novel annotation procedure, where the unknown motion data is segmented and annotated by locally comparing it with the available motion templates. This procedure is supported by an efficient keyframe-based preprocessing step, which also significantly improves the annotation quality by eliminating false positive matches. As a further contribution, we introduce a genetic learning algorithm to automatically learn the necessary keyframes from the given example motions. For evaluation, we report on various experiments conducted on two freely available sets of motion capture data (CMU and HDM05).Item Real-Time Bump Map Synthesis(The Eurographics Association, 2001) Kautz, Jan; Heidrich, Wolfgang; Seidel, Hans-Peter; Kurt Akeley and Ulrich NeumannIn this paper we present a method that automatically synthesizes bump maps at arbitrary levels of detail in real-time. The only input data we require is a normal density function; the bump map is generated according to that function. It is also used to shade the generated bump map. The technique allows to infinitely zoom into the surface, because more (consistent) detail can be created on the fly. The shading of such a surface is consistent when displayed at different distances to the viewer (assuming that the surface structure is self-similar). The bump map generation and the shading algorithm can also be used separately.Item Bayesian Relighting(The Eurographics Association, 2005) Fuchs, Martin; Blanz, Volker; Seidel, Hans-Peter; Kavita Bala and Philip DutreWe present a simple method for relighting real objects viewed from a fixed camera position. Instead of setting up a calibrated measurement device, such as a light stage, we manually sweep a spotlight over the walls of a white room, illuminating the object indirectly. In contrast to previous methods, we use arbitrary and unknown angular distributions of incoming light. Neither the incident light nor the reflectance function need to be represented explicitly in our approach. The new method relies on images of a probe object, for instance a black snooker ball, placed near the target object. Pictures of the probe in a novel illumination are decomposed into a linear combination of measured images of the probe. Then, a linear combination of images of the target object with the same coefficients produces a synthetic image with the new illumination. We use a simple Bayesian approach to find the most plausible output image, given the picture of the probe and the statistics observed in the dataset of samples. Our results for a variety of novel illuminations, including synthetic lighting by relatively narrow light sources as well as natural illuminations, demonstrate that the new technique is a useful, low cost alternative to existing techniques for a broad range of objects and materials.Item Robust Filtering of Noisy Scattered Point Data(The Eurographics Association, 2005) Schall, Oliver; Belyaev, Alexander; Seidel, Hans-Peter; Marc Alexa and Szymon Rusinkiewicz and Mark Pauly and Matthias ZwickerIn this paper, we develop a method for robust filtering of a noisy set of points sampled from a smooth surface. The main idea of the method consists of using a kernel density estimation technique for point clustering. Specifically, we use a mean-shift based clustering procedure. With every point of the input data we associate a local likelihood measure capturing the probability that a 3D point is located on the sampled surface. The likelihood measure takes into account the normal directions estimated at the scattered points. Our filtering procedure suppresses noise of different amplitudes and allows for an easy detection of outliers which are then automatically removed by simple thresholding. The remaining set of maximum likelihood points delivers an accurate point-based approximation of the surface. We also show that while some established meshing techniques often fail to reconstruct the surface from original noisy point scattered data, they work well in conjunction with our filtering method.Item Harmonic Guidance for Surface Deformation(The Eurographics Association and Blackwell Publishing, Inc, 2005) Zayer, Rhaleb; Roessl, Christian; Karni, Zachi; Seidel, Hans-PeterItem Efficient Rendering of Local Subsurface Scattering(The Eurographics Association and Blackwell Publishing Ltd., 2005) Mertens, Tom; Kautz, Jan; Bekaert, Philippe; Van Reeth, Frank; Seidel, Hans-PeterA novel approach is presented to efficiently render local subsurface scattering effects. We introduce an importance sampling scheme for a practical subsurface scattering model. It leads to a simple and efficient rendering algorithm, which operates in image space, and which is even amenable for implementation on graphics hardware. We demonstrate the applicability of our technique to the problem of skin rendering, for which the subsurface transport of light typically remains local. Our implementation shows that plausible images can be rendered interactively using hardware acceleration.Item Fast Final Gathering via Reverse Photon Mapping(The Eurographics Association and Blackwell Publishing, Inc, 2005) Havran, Vlastimil; Herzog, Robert; Seidel, Hans-PeterItem Editing Object Behaviour in Video Sequences(The Eurographics Association and Blackwell Publishing Ltd, 2009) Scholz, Volker; El-Abed, Sascha; Seidel, Hans-Peter; Magnor, MarcusWhile there are various commercial-strength editing tools available today for still images, object-based manipulation of real-world video footage is still a challenging problem. In this system paper, we present a framework for interactive video editing. Our focus is on footage from a single, conventional video camera. By relying on spatio-temporal editing techniques operating on the video cube, we do not need to recover 3D scene geometry. Our framework is capable of removing and inserting objects, object motion editing, non-rigid object deformations, keyframe interpolation, as well as emulating camera motion. We demonstrate how movie shots with moderate complexity can be persuasively modified during post-processing.Item An Efficient Spatio-Temporal Architecture for Animation Rendering(The Eurographics Association, 2003) Havran, Vlastimil; Damez, Cyrille; Myszkowski, Karol; Seidel, Hans-Peter; Philip Dutre and Frank Suykens and Per H. Christensen and Daniel Cohen-OrProducing high quality animations featuring rich object appearance and compelling lighting effects is very time consuming using traditional frame-by-frame rendering systems. In this paper we present a rendering architecture for computing multiple frames at once by exploiting the coherencebetween image samples in the temporal domain. For each sample representing a given point in the scene we update its view-dependent components for each frame and add its contribution to pixels identified through the compensation of camera and object motion. This leads naturally to a high quality motion blur and significantly reduces the cost of illumination computations. The required visibility information is provided using a custom ray tracing acceleration data structure for multiple frames simultaneously. We demonstrate that precise and costly global illumination techniques such as bidirectional path tracing become affordable in this rendering architecture.