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Variational shape approximation
 ACM Trans. Graph
, 2004
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Cited by 165 (4 self)
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Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or direct commercial advantage and that copies show this notice on the first page or initial screen of a display along with the full citation. Copyrights for components of this work owned by others than ACM must be honored. Abstracting with credit is permitted. To copy otherwise, to republish, to post on servers, to redistribute to lists, or to use any component of this work in other works requires prior specific permission and/or a fee.
Interactive rendering of large unstructured grids using dynamic levelofdetail
 In IEEE Visualization ’05
, 2005
"... We describe a new dynamic levelofdetail (LOD) technique that allows realtime rendering of large tetrahedral meshes. Unlike approaches that require hierarchies of tetrahedra, our approach uses a subset of the faces that compose the mesh. No connectivity is used for these faces so our technique eli ..."
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Cited by 32 (10 self)
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We describe a new dynamic levelofdetail (LOD) technique that allows realtime rendering of large tetrahedral meshes. Unlike approaches that require hierarchies of tetrahedra, our approach uses a subset of the faces that compose the mesh. No connectivity is used for these faces so our technique eliminates the need for topological information and hierarchical data structures. By operating on a simple set of triangular faces, our algorithm allows a robust and straightforward graphics hardware (GPU) implementation. Because the subset of faces processed can be constrained to arbitrary size, interactive rendering is possible for a wide range of data sets and hardware configurations.
Optimized SubSampling of Point Sets for Surface Splatting
 Computer Graphics Forum
, 2004
"... Using surface splats as a rendering primitive has gained increasing attention recently due to its potential for highperformance and highquality rendering of complex geometric models. However, as with any other rendering primitive, the processing costs are still proportional to the number of prim ..."
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Cited by 23 (0 self)
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Using surface splats as a rendering primitive has gained increasing attention recently due to its potential for highperformance and highquality rendering of complex geometric models. However, as with any other rendering primitive, the processing costs are still proportional to the number of primitives that we use to represent a given object. This is why complexity reduction for pointsampled geometry is as important as it is, e.g., for triangle meshes. In this paper we present a new subsampling technique for dense point clouds which is specifically adjusted to the particular geometric properties of circular or elliptical surface splats. A global optimization scheme computes an approximately minimal set of splats that covers the entire surface while staying below a globally prescribed maximum error tolerance #. Since our algorithm converts pure point sample data into surface splats with normal vectors and spatial extent, it can also be considered as a surface reconstruction technique which generates a holefree piecewise linear C continuous approximation of the input data. Here we can exploit the higher flexibility of surface splats compared to triangle meshes. Compared to previous work in this area we are able to obtain significantly lower splat numbers for a given error tolerance.
SamplingBased Motion Planning with Differential Constraints

, 2005
"... Since differential constraints which restrict admissible velocities and accelerations of robotic systems are ignored in path planning, solutions for kinodynamic and nonholonomic planning problems from classical methods could be either inexecutable or inefficient. Motion planning with differential c ..."
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Cited by 22 (4 self)
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Since differential constraints which restrict admissible velocities and accelerations of robotic systems are ignored in path planning, solutions for kinodynamic and nonholonomic planning problems from classical methods could be either inexecutable or inefficient. Motion planning with differential constraints (MPD), which directly considers differential constraints, provides a promising direction to calculate reliable and efficient solutions. A large amount of recent efforts have been devoted to various samplingbased MPD algorithms, which iteratively build search graphs using sampled states and controls. This thesis addresses several issues in analysis and design of these algorithms. Firstly, resolution completeness of path planning is extended to MPD and the first quantitative conditions are provided. The analysis is based on the relationship between the reachability graph, which is an intrinsic graph representation of a given problem, and the search graph, which is built by the algorithm. Because of sampling and other complications, there exist mismatches between these two graphs. If a solution exists in the reachability graph, resolution complete algorithms must construct a solution path encoding the solution or its approximation in the search graph
Realistic RealTime Rendering of Landscapes Using Billboard Clouds
 IN COMPUTER GRAPHICS FORUM (2005). (PROCEEDINGS OF EUROGRAPHICS
, 2005
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The mental canvas: A tool for conceptual architectural design and analysis
 P & P
, 1979
"... We describe a computer graphics system that supports conceptual architectural design and analysis. We use as a starting point the traditional sketchbook drawings that architects use to experiment with various views, sections, and details. Rather than interpret or infer 3D structure from drawings, ou ..."
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Cited by 13 (2 self)
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We describe a computer graphics system that supports conceptual architectural design and analysis. We use as a starting point the traditional sketchbook drawings that architects use to experiment with various views, sections, and details. Rather than interpret or infer 3D structure from drawings, our system is designed to allow the designer to organize concept drawings in 3D, and gradually fuse a series of possibly geometricallyinconsistent sketches into a set of 3D strokes. Our system uses strokes and planar “canvases” as basic primitives; the basic mode of input is traditional 2D drawing. We introduce methods for the user to control stroke visibility and transfer strokes between canvases. We also introduce methods for the user to position and orient the canvases that have infinite extent. We demonstrate the use of the system to analyze existing structures and conceive new designs. 1
Identifying Planes in PointClouds for Efficient Hybrid Rendering
 In The 13th Pacific Conference on Computer Graphics and Applications
, 2005
"... We present a hybrid rendering technique for highfeature colored point clouds that achieves both, high performance and high quality. Planar subsets in the point cloud are identified to drastically reduce the number of vertices, thus saving transformation bandwidth at the cost of the much higher fill ..."
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Cited by 9 (1 self)
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We present a hybrid rendering technique for highfeature colored point clouds that achieves both, high performance and high quality. Planar subsets in the point cloud are identified to drastically reduce the number of vertices, thus saving transformation bandwidth at the cost of the much higher fillrate. Moreover, when rendering the planes, the filtering is comparable to elaborate pointrendering methods but significantly faster since it is supported in hardware. This way we achieve at least a 5 times higher performance than simple point rendering and a 40 times higher than a splatting technique with comparable quality. The preprocessing performance is orders of magnitude faster than comparable high quality point cloud simplification techniques. The plane detection is based on the random sample consensus (RANSAC) approach, which easily finds multiple structures without using the expensive Hough transform. Additionally, we use an octree in order to identify planar representations at different scales and accuracies for levelofdetail selection during rendering. The octree has the additional advantage of limiting the number of planar structures, thereby making their detection faster and more robust. Furthermore, the spatial subdivision facilitates handling outofcore point clouds, both in preprocessing and rendering.
Automated ReprojectionBased Pixel Shader Optimization
 TO APPEAR IN THE ACM SIGGRAPH CONFERENCE PROCEEDINGS
"... Several optimization results produced with our system. Each image compares (top) an input pixel shader to (bottom) a version modified to cache and reuse some partial shading computations over consecutive frames. Our system automatically selects the intermediate values to be reused and the rate at wh ..."
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Cited by 8 (2 self)
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Several optimization results produced with our system. Each image compares (top) an input pixel shader to (bottom) a version modified to cache and reuse some partial shading computations over consecutive frames. Our system automatically selects the intermediate values to be reused and the rate at which cached entries are refreshed so as to maximize performance improvement while minimizing (inset) the visual error injected into the final shading. We present a framework and supporting algorithms to automate the use of data reprojection as a general tool for optimizing procedural shaders. Although the general strategy of caching and reusing expensive intermediate shading calculations across consecutive frames has previously been shown to provide an effective tradeoff between speed and accuracy, the critical choices of what to reuse and at what rate to explicitly refresh cached entries have always been left to a designer. The fact that these decisions require a deep understanding of a procedure’s semantic structure makes it challenging to select optimal candidates among possibly hundreds of alternatives. Our automated approach relies on parametric models of the way possible caching decisions affect the shader’s performance and visual fidelity. These models are trained using a sample rendering session and drive an interactive profiler in which the user can explore the error/performance tradeoffs associated with incorporating temporal reprojection. We evaluate the proposed models and selection algorithm with a prototype system used to optimize several complex shaders; in each case we observed a significant performance improvement. We also compare our approach to current alternatives.
Realtime rendering of complex photorealistic landscapes using hybrid levelofdetail approaches
 Trends in RealTime Landscape Visualization and Participation
, 2005
"... It still remains a challenge to realistically render outdoor scenes with interactive framerates since these scenes consist of a immense number of highly complex geometric models. A square kilometre of a forest incorporates millions of plants, hundreds of thousands of trees, and numerous small shrubs ..."
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Cited by 8 (2 self)
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It still remains a challenge to realistically render outdoor scenes with interactive framerates since these scenes consist of a immense number of highly complex geometric models. A square kilometre of a forest incorporates millions of plants, hundreds of thousands of trees, and numerous small shrubs. Even the explicit storage of the plant positions is
Perceptual evaluation of impostor representations for virtual humans and buildings. Computer Graphics Forum (Eurographics 2005
 Computer Graphics Forum
, 2005
"... In largescale simulations involving complex scenes, such as cities inhabited by crowds, simplifications are almost always necessary to achieve interactive framerates. Level of Detail (LOD) techniques such as reducing geometric complexity, or substituting impostor images for geometry, are usually e ..."
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Cited by 8 (4 self)
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In largescale simulations involving complex scenes, such as cities inhabited by crowds, simplifications are almost always necessary to achieve interactive framerates. Level of Detail (LOD) techniques such as reducing geometric complexity, or substituting impostor images for geometry, are usually employed. Imagebased or impostor techniques have been gaining in popularity in recent years, along with hybrid methods that combine impostors and geometry, but perceptual issues with respect to such representations have been largely neglected to date. In this paper we evaluate the effectiveness of impostor representations for the realtime rendering and animation of static buildings and dynamic virtual humans. Using sets of psychophysical experiments, we establish some thresholds at which impostors are effective for static and dynamic objects, along with criteria for selecting transitions to geometry and update rates. We also compare the impact of two model representations (geometry and impostor), on the perception of human motion. We have found that impostors are an extremely effective substitute for detailed geometry in the target application area. Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Virtual Reality, Perception 1.