bluuebunny/crossref_metadata_2025_split huggingface dataset:
Geodesic‐Controlled Developable Surfaces for Modeling Paper Bending
Authors: Bo Pengbo , Wang Wenping 
Published: October 2007

Abstract We present a novel and effective method for modeling a developable surface to simulate paper bending in interactive and animation applications. The method exploits the representation of a developable surface as the envelope of rectifying planes of a curve in 3D, which is therefore necessarily a geodesic on the surface. We manipulate the geodesic to provide intuitive shape control for modeling paper bending. Our method ensures a natural continuous isometric deformation from a piece of bent paper to its flat state without any stretching. Test examples show that the new scheme is fast, accurate, and easy to use, thus providing an effective approach to interactive paper bending. We also show how to handle non‐convex piecewise smooth developable surfaces.
QuadCover ‐ Surface Parameterization using Branched Coverings
Authors: Kälberer Felix , Nieser Matthias , Polthier Konrad 
Published: October 2007

AbstractWe introduce an algorithm for the automatic computation of global parameterizations on arbitrary simplicial 2‐manifolds, whose parameter lines are guided by a given frame field, for example, by principal curvature frames. The parameter lines are globally continuous and allow a remeshing of the surface into quadrilaterals. The algorithm converts a given frame field into a single vector field on a branched covering of the 2‐manifold and generates an integrable vector field by a Hodge decomposition on the covering space. Except for an optional smoothing and alignment of the initial frame field, the algorithm is fully automatic and generates high quality quadrilateral meshes.
Mesh Segmentation via Spectral Embedding and Contour Analysis
Authors: Liu Rong , Zhang Hao 
Published: October 2007

Abstract We propose a mesh segmentation algorithm via recursive bisection where at each step, a sub‐mesh embedded in 3D is first spectrally projected into the plane and then a contour is extracted from the planar embedding. We rely on two operators to compute the projection: the well‐known graph Laplacian and a geometric operator designed to emphasize concavity. The two embeddings reveal distinctive shape semantics of the 3D model and complement each other in capturing the structural or geometrical aspect of a segmentation. Transforming the shape analysis problem to the 2D domain also facilitates our segmentability analysis and sampling tasks. We propose a novel measure of the segmentability of a shape, which is used as the stopping criterionfor our segmentation. The measure is derived from simple area‐ and perimeter‐based convexity measures. We achieve invariance to shape bending through multi‐dimensional scaling (MDS) based on the notion of inner distance. We also utilize inner distances to develop a novel sampling scheme to extract two samples along a contour which correspond to two vertices residing on different parts of the sub‐mesh. The two samples are used to derive a spectral linear ordering of the mesh faces. We obtain a final cut via a linear search over the face sequence based on part salience, where a choice of weights for different factors of part salience is guided by the result from segmentability analysis.
Highly Parallel Fast KD‐tree Construction for Interactive Ray Tracing of Dynamic Scenes
Authors: Shevtsov Maxim , Soupikov Alexei , Kapustin Alexander 
Published: October 2007

Abstract We present a highly parallel, linearly scalable technique of kd‐tree construction for ray tracing of dynamic geometry. We use conventional kd‐tree compatible with the high performing algorithms such as MLRTA or frustum tracing. Proposed technique offers exceptional construction speed maintaining reasonable kd‐tree quality for rendering stage. The algorithm builds a kd‐tree from scratch each frame, thus prior knowledge of motion /deformation or motion constraints are not required. We achieve nearly real‐time performance of 7‐12 FPS for models with 200K of dynamic triangles at 1024x1024 resolution with shadows and textures.
Stackless KD‐Tree Traversal for High Performance GPU Ray Tracing
Authors: Popov Stefan , Günther Johannes , Seidel Hans‐Peter , Slusallek Philipp 
Published: October 2007

Abstract Significant advances have been achieved for realtime ray tracing recently, but realtime performance for complex scenes still requires large computational resources not yet available from the CPUs in standard PCs. Incidentally, most of these PCs also contain modern GPUs that do offer much larger raw compute power. However, limitations in the programming and memory model have so far kept the performance of GPU ray tracers well below that of their CPU counterparts. In this paper we present a novel packet ray traversal implementation that completely eliminates the need for maintaining a stack during kd‐tree traversal and that reduces the number of traversal steps per ray. While CPUs benefit moderately from the stackless approach, it improves GPU performance significantly. We achieve a peak performance of over 16 million rays per second for reasonably complex scenes, including complex shading and secondary rays. Several examples show that with this new technique GPUs can actually outperform equivalent CPU based ray tracers.
A Bidirectional Light Field ‐ Hologram Transform
Authors: Ziegler Remo , Bucheli Simon , Ahrenberg Lukas , Magnor Marcus , Gross Markus 
Published: October 2007

Abstract In this paper, we propose a novel framework to represent visual information. Extending the notion of conventional image‐based rendering, our framework makes joint use of both light fields and holograms as complementary representations. We demonstrate how light fields can be transformed into holograms, and vice versa. By exploiting the advantages of either representation, our proposed dual representation and processing pipeline is able to overcome the limitations inherent to light fields and holograms alone. We show various examples from synthetic and real light fields to digital holograms demonstrating advantages of either representation, such as speckle‐free images, ghosting‐free images, aliasing‐free recording, natural light recording, aperture‐dependent effects and real‐time rendering which can all be achieved using the same framework. Capturing holograms under white light illumination is one promising application for future work.
Markerless 4 gestures 6 DOF real‐time visual tracking of the human hand with automatic initialization
Authors: Schlattmann Markus , Kahlesz Ferenc , Sarlette Ralf , Klein Reinhard 
Published: October 2007

Abstract In this paper we present a novel computer vision based hand‐tracking technique, which is capable of robustly tracking 6+4DOF of the human hand in real‐time (at least 25 frames per second) with the help of 3 (or more) off‐the‐shelf consumer cameras. ‘6+4DOF’ means that the system can track the global pose (6 continuous parameters for translation and rotation) of 4 different gestures. A key feature of our system is its fully automatic real‐time initialization procedure, which, along with a sound tracking‐lost detector, makes the system fit for real‐world applications. Because of this, our method acts as an enabling technology for uncumbersome hand‐based 3D Human‐Computer‐Interaction (HCI). Previously, using the hand as an at least 6DOF input device involved the use of either datagloves or markers. Using our tracking we evaluated the use of the hand as an input device for two prevalent Virtual Reality applications: fly‐through exploration of a virtual world and a simple digital assembly simulation.
Efficient Reflectance and Visibility Approximations for Environment Map Rendering
Authors: Green Paul , Kautz Jan , Durand Frédo 
Published: October 2007

Abstract We present a technique for approximating isotropic BRDFs and precomputed self‐occlusion that enables accurate and efficient prefiltered environment map rendering. Our approach uses a nonlinear approximation of the BRDF as a weighted sum of isotropic Gaussian functions. Our representation requires a minimal amount of storage, can accurately represent BRDFs of arbitrary sharpness, and is above all, efficient to render. We precompute visibility due to self‐occlusion and store a low‐frequency approximation suitable for glossy reflections. We demonstrate our method by fitting our representation to measured BRDF data, yielding high visual quality at real‐time frame rates.
High‐Quality Adaptive Soft Shadow Mapping
Authors: Guennebaud Gaël , Barthe Loïc , Paulin Mathias 
Published: October 2007

Abstract The recent soft shadow mapping technique [GBP06] allows the rendering in real‐time of convincing soft shadows on complex and dynamic scenes using a single shadow map. While attractive, this method suffers from shadow overestimation and becomes both expensive and approximate when dealing with large penumbrae. This paper proposes new solutions removing these limitations and hence providing an efficient and practical technique for soft shadow generation. First, we propose a new visibility computation procedure based on the detection of occluder contours, that is more accurate and faster while reducing aliasing. Secondly, we present a shadow map multi‐resolution strategy keeping the computation complexity almost independent on the light size while maintaining high‐quality rendering. Finally, we propose a view‐dependent adaptive strategy, that automatically reduces the screen resolution in the region of large penumbrae, thus allowing us to keep very high frame rates in any situation.
Visibility Sampling on GPU and Applications
Authors: Eisemann Elmar , Décoret Xavier 
Published: October 2007

Abstract In this paper, we show how recent GPUs can be used to very efficiently and conveniently sample the visibility between two surfaces, given a set of occluding triangles. We use bitwise arithmetics to evaluate, encode, and combine the samples blocked by each triangle. In particular, the number of operations is almost independent of the number of samples. Our method requires no CPU/GPU transfers, is fully implemented as geometric, vertex and fragment shaders, and thus does not impose to modify the way the geometry is sent to the graphics card. We finally present applications to soft shadows, and visibility analysis for level design.
Real‐time homogenous translucent material editing
Authors: Xu Kun , Gao Yue , Li Yong , Ju Tao , Hu Shi‐Min 
Published: October 2007

Abstract This paper presents a novel method for real‐time homogenous translucent material editing under fixed illumination. We consider the complete analytic BSSRDF model proposed by Jensen et al. [JMLH01], including both multiple scattering and single scattering. Our method allows the user to adjust the analytic parameters of BSSRDF and provides high‐quality, real‐time rendering feedback. Inspired by recently developed Precomputed Radiance Transfer (PRT) techniques, we approximate both the multiple scattering diffuse reflectance function and the single scattering exponential attenuation function in the analytic model using basis functions, so that re‐computing the outgoing radiance at each vertex as parameters change reduces to simple dot products. In addition, using a non‐uniform piecewise polynomial basis, we are able to achieve smaller approximation error than using bases adopted in previous PRT‐based works, such as spherical harmonics and wavelets. Using hardware acceleration, we demonstrate that our system generates images comparable to [JMLH01]at real‐time frame‐rates.
Defocus Magnification
Authors: Bae Soonmin , Durand Frédo 
Published: October 2007

Abstract A blurry background due to shallow depth of field is often desired for photographs such as portraits, but, unfortunately, small point‐and‐shoot cameras do not permit enough defocus because of the small diameter of their lenses. We present an image‐processing technique that increases the defocus in an image to simulate the shallow depth of field of a lens with a larger aperture. Our technique estimates the spatially‐varying amount of blur over the image, and then uses a simple image‐based technique to increase defocus. We first estimate the size of the blur kernel at edges and then propagate this defocus measure over the image. Using our defocus map, we magnify the existing blurriness, which means that we blur blurry regions and keep sharp regions sharp. In contrast to more difficult problems such as depth from defocus, we do not require precise depth estimation and do not need to disambiguate textureless regions.
Contrast Restoration by Adaptive Countershading
Authors: Krawczyk Grzegorz , Myszkowski Karol , Seidel Hans‐Peter 
Published: October 2007

Abstract The ABSTRACT is to be in fully‐justified italicized text, between two horizontal lines, in one‐column format, below the author and affiliation information. Use the word “Abstract” as the title, in 9‐point Times, boldface type, left‐aligned to the text, initially capitalized. The abstract is to be in 9‐point, single‐spaced type. The abstract may be up to 3 inches (7.62 cm) long. Leave one blank line after the abstract, then add the subject categories according to the ACM Classification Index (see http://www.acm.org/class/1998/).
Synthetic Shutter Speed Imaging
Authors: Telleen J. , Sullivan A. , Yee J. , Wang O. , Gunawardane P. , Collins I. , Davis J. 
Published: October 2007

Abstract Hand held long exposures often result in blurred photographs due to camera shake. Long exposures are desirable both for artistic effect and in low‐light situations. We propose a novel method for digitally reducing imaging artifacts, which does not require additional hardware such as tripods or optical image stabilization lenses. A series of photographs is acquired with short shutter times, stabilized using image alignment, and then composited. Our method is capable of reducing noise and blurring due to camera shake, while simultaneously preserving the desirable effects of motion blur. The resulting images are very similar to those obtained using a tripod and a true extended exposure.
Diorama Construction From a Single Image
Authors: Assa J. , Wolf L. 
Published: October 2007

Abstract Diorama artists produce a spectacular 3D effect in a confined space by generating depth illusions that are faithful to the ordering of the objects in a large real or imaginary scene. Indeed, cognitive scientists have discovered that depth perception is mostly affected by depth order and precedence among objects. Motivated by these findings, we employ ordinal cues to construct a model from a single image that similarly to Dioramas, intensifies the depth perception. We demonstrate that such models are sufficient for the creation of realistic 3D visual experiences. The initial step of our technique extracts several relative depth cues that are well known to exist in the human visual system. Next, we integrate the resulting cues to create a coherent surface. We introduce wide slits in the surface, thus generalizing the concept of cardboard cutout layers. Lastly, the surface geometry and texture are extended alongside the slits, to allow small changes in the viewpoint which enriches the depth illusion.
A Generic Pigment Model for Digital Painting
Authors: Xu Songhua , Tan Haisheng , Jiao Xiantao , Lau Francis C.M. , Pan Yunhe 
Published: October 2007

Abstract We propose a generic pigment model suitable for digital painting in a wide range of genres including traditional Chinese painting and water‐based painting. The model embodies a simulation of the pigment‐water solution and its interaction with the brush and the paper at the level of pigment particles; such a level of detail is needed for achieving highly intricate effects by the artist. The simulation covers pigment diffusion and sorption processes at the paper surface, and aspects of pigment particle deposition on the paper. We follow rules and formulations from quantitative studies of adsorption and diffusion processes in surface chemistry and the textile industry. The result is a pigment model that spans a continuum from the very wet to the very dry brush stroke effects. We also propose a new pigment mixing method based on machine learning techniques to emulate pigment mixing in real life as well as to support the creation of new artificial pigments. To experiment with the proposed model, we embedded the model in a sophisticated digital brush system. The combined system exhibits interactive speed on a modest PC platform. http://www.cs.hku.hk/~songhua/pigment provides supplementary materials for this paper.
Image Dequantization: Restoration of Quantized Colors
Authors: Kim Tae‐hoon , Ahn Jongwoo , Choi Min Gyu 
Published: October 2007

Abstract Color quantization replaces the color of each pixel with the closest representative color, and thus it makes the resulting image partitioned into uniformly‐colored regions. As a consequence, continuous, detailed variations of color over the corresponding regions in the original image are lost through color quantization. In this paper, we present a novel blind scheme for restoring such variations from a color‐quantized input image without a priori knowledge of the quantization method. Our scheme identifies which pairs of uniformly‐colored regions in the input image should have continuous variations of color in the resulting image. Then, such regions are seamlessly stitched through optimization while preserving the closest representative colors. The user can optionally indicate which regions should be separated or stitched by scribbling constraint brushes across the regions. We demonstrate the effectiveness of our approach through diverse examples, such as photographs, cartoons, and artistic illustrations.
Texturing Internal Surfaces from a Few Cross Sections
Authors: Pietroni Nico , Otaduy Miguel A. , Bickel Bernd , Ganovelli Fabio , Gross Markus 
Published: October 2007

Abstract We introduce a new appearance‐modeling paradigm for synthesizing the internal structure of a 3D model from photographs of a few cross‐sections of a real object. When the internal surfaces of the 3D model are revealed as it is cut, carved, or simply clipped, we synthesize their texture from the input photographs. Our texture synthesis algorithm is best classified as a morphing technique, which efficiently outputs the texture attributes of each surface point on demand. For determining source points and their weights in the morphing algorithm, we propose an interpolation domain based on BSP trees that naturally resembles planar splitting of real objects. In the context of the interpolation domain, we define efficient warping and morphing operations that allow for real‐time synthesis of textures. Overall, our modeling paradigm, together with its realization through our texture morphing algorithm, allow users to author 3D models that reveal highly realistic internal surfaces in a variety of artistic flavors.
Depth‐of‐Field Rendering by Pyramidal Image Processing
Authors: Kraus M. , Strengert M. 
Published: October 2007

Abstract We present an image‐based algorithm for interactive rendering depth‐of‐field effects in images with depth maps. While previously published methods for interactive depth‐of‐field rendering suffer from various rendering artifacts such as color bleeding and sharpened or darkened silhouettes, our algorithm achieves a significantly improved image quality by employing recently proposed GPU‐based pyramid methods for image blurring and pixel disocclusion. Due to the same reason, our algorithm offers an interactive rendering performance on modern GPUs and is suitable for real‐time rendering for small circles of confusion. We validate the image quality provided by our algorithm by side‐by‐side comparisons with results obtained by distributed ray tracing.
Crowds by Example
Authors: Lerner Alon , Chrysanthou Yiorgos , Lischinski Dani 
Published: October 2007

AbstractWe present an example‐based crowd simulation technique. Most crowd simulation techniques assume that the behavior exhibited by each person in the crowd can be defined by a restricted set of rules. This assumption limits the behavioral complexity of the simulated agents. By learning from real‐world examples, our autonomous agents display complex natural behaviors that are often missing in crowd simulations. Examples are created from tracked video segments of real pedestrian crowds. During a simulation, autonomous agents search for examples that closely match the situation that they are facing. Trajectories taken by real people in similar situations, are copied to the simulated agents, resulting in seemingly natural behaviors.
Layered Performance Animation with Correlation Maps
Authors: Neff Michael , Albrecht Irene , Seidel Hans‐Peter 
Published: October 2007

Abstract Performance has a spontaneity and “aliveness” that can be difficult to capture in more methodical animation processes such as keyframing. Access to performance animation has traditionally been limited to either low degree of freedom characters or required expensive hardware. We present a performance‐based animation system for humanoid characters that requires no special hardware, relying only on mouse and keyboard input. We deal with the problem of controlling such a high degree of freedom model with low degree of freedom input through the use of correlation maps which employ 2D mouse input to modify a set of expressively relevant character parameters. Control can be continuously varied by rapidly switching between these maps. We present flexible techniques for varying and combining these maps and a simple process for defining them. The tool is highly configurable, presenting suitable defaults for novices and supporting a high degree of customization and control for experts. Animation can be recorded on a single pass, or multiple layers can be used to increase detail. Results from a user study indicate that novices are able to produce reasonable animations within their first hour of using the system. We also show more complicated results for walking and a standing character that gestures and dances.
Interactive Visual Workspaces with Dynamic Foveal Areas and Adaptive Composite Interfaces
Authors: Cotting Daniel , Gross Markus 
Published: October 2007

AbstractThis paper presents novel techniques and metaphors for on‐demand visual workspaces in everyday office environments, providing space‐efficient, flexible and highly interactive graphical user interfaces using projected displays. For increased resolution, contents personalization and interactive visualization, the users can augment the large‐scale projections with dynamic high‐resolution foveal enhancements using a pocket light metaphor. To further optimize the presentation at a given resolution, the design of the displays can be modified interactively, and like a jigsaw puzzle, the layout can be customized using an adaptive compositing approach which supports free‐form focus‐and‐context rendering. With a unified intensity‐based tracking approach, we allow for natural multi‐touch interaction with the information space through bare hands, pointers and pens on arbitrary surfaces.