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18
QSplat: A Multiresolution Point Rendering System for Large Meshes
, 2000
"... Advances in 3D scanning technologies have enabled the practical creation of meshes with hundreds of millions of polygons. Traditional algorithms for display, simplification, and progressive transmission of meshes are impractical for data sets of this size. We describe a system for representing and p ..."
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Cited by 427 (9 self)
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Advances in 3D scanning technologies have enabled the practical creation of meshes with hundreds of millions of polygons. Traditional algorithms for display, simplification, and progressive transmission of meshes are impractical for data sets of this size. We describe a system for representing and progressively displaying these meshes that combines a multiresolution hierarchy based on bounding spheres with a rendering system based on points. A single data structure is used for view frustum culling, backface culling, levelofdetail selection, and rendering. The representation is compact and can be computed quickly, making it suitable for large data sets. Our implementation, written for use in a largescale 3D digitization project, launches quickly, maintains a usersettable interactive frame rate regardless of object complexity or camera position, yields reasonable image quality during motion, and refines progressively when idle to a high final image quality. We have demonstrated the system on scanned models containing hundreds of millions of samples.
Efficient collision detection using bounding volume hierarchies of kdops
 IEEE Transactions on Visualization and Computer Graphics
, 1998
"... Abstract—Collision detection is of paramount importance for many applications in computer graphics and visualization. Typically, the input to a collision detection algorithm is a large number of geometric objects comprising an environment, together with a set of objects moving within the environment ..."
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Cited by 228 (4 self)
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Abstract—Collision detection is of paramount importance for many applications in computer graphics and visualization. Typically, the input to a collision detection algorithm is a large number of geometric objects comprising an environment, together with a set of objects moving within the environment. In addition to determining accurately the contacts that occur between pairs of objects, one needs also to do so at realtime rates. Applications such as haptic forcefeedback can require over 1,000 collision queries per second. In this paper, we develop and analyze a method, based on boundingvolume hierarchies, for efficient collision detection for objects moving within highly complex environments. Our choice of bounding volume is to use a “discrete orientation polytope” (“kdop”), a convex polytope whose facets are determined by halfspaces whose outward normals come from a small fixed set of k orientations. We compare a variety of methods for constructing hierarchies (“BVtrees”) of bounding kdops. Further, we propose algorithms for maintaining an effective BVtree of kdops for moving objects, as they rotate, and for performing fast collision detection using BVtrees of the moving objects and of the environment. Our algorithms have been implemented and tested. We provide experimental evidence showing that our approach yields substantially faster collision detection than previous methods. Index Terms—Collision detection, intersection searching, bounding volume hierarchies, discrete orientation polytopes, bounding boxes, virtual reality, virtual environments. 1
Feature Sensitive Surface Extraction from Volume Data
"... The representation of geometric objects based on volumetric data structures has advantages in many geometry processing applications that require, e.g., fast surface interrogation or boolean operations such as intersection and union. However, surface based algorithms like shape optimization (fairing) ..."
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Cited by 123 (8 self)
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The representation of geometric objects based on volumetric data structures has advantages in many geometry processing applications that require, e.g., fast surface interrogation or boolean operations such as intersection and union. However, surface based algorithms like shape optimization (fairing) or freeform modeling often need a topological manifold representation where neighborhood information within the surface is explicitly available. Consequently, it is necessary to find effective conversion algorithms to generate explicit surface descriptions for the geometry which is implicitly defined by a volumetric data set. Since volume data is usually sampled on a regular grid with a given step width, we often observe severe alias artifacts at sharp features on the extracted surfaces. In this paper we present a new technique for surface extraction that performs feature sensitive sampling and thus reduces these alias effects while keeping the simple algorithmic structure of the standard Marching Cubes algorithm. We demonstrate the effectiveness of the new technique with a number of application examples ranging from CSG modeling and simulation to surface reconstruction and remeshing of polygonal models. 1
Interactive Ray Tracing for Volume Visualization
, 1999
"... We present a bruteforce ray tracing system for interactive volume visualization. The system runs on a conventional (distributed) sharedmemory multiprocessor machine. For each pixel we trace a ray through a volume to compute the color for that pixel. Although this method has high intrinsic computat ..."
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Cited by 103 (26 self)
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We present a bruteforce ray tracing system for interactive volume visualization. The system runs on a conventional (distributed) sharedmemory multiprocessor machine. For each pixel we trace a ray through a volume to compute the color for that pixel. Although this method has high intrinsic computational cost, its simplicity and scalability make it ideal for large datasets on current highend parallel systems. To gain efficiency several optimizations are used including a volume bricking scheme and a shallow data hierarchy. These optimizations are used in three separate visualization algorithms: isosurfacing of rectilinear data, isosurfacing of unstructured data, and maximumintensity projection on rectilinear data. The system runs interactively (i.e., several frames per second) on an SGI Reality Monster. The graphics capabilities of the Reality Monster are used only for display of the final color image.
Ray Tracing Deformable Scenes using Dynamic Bounding Volume Hierarchies
 ACM Transactions on Graphics
, 2006
"... The most significant deficiency of most of today’s interactive ray tracers is that they are restricted to static walkthroughs. This restriction is due to the static nature of the acceleration structures used. While the best reported frame rates for static geometric models have been achieved using ca ..."
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Cited by 84 (18 self)
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The most significant deficiency of most of today’s interactive ray tracers is that they are restricted to static walkthroughs. This restriction is due to the static nature of the acceleration structures used. While the best reported frame rates for static geometric models have been achieved using carefully constructed kdtrees, this article shows that bounding volume hierarchies (BVHs) can be used to efficiently ray trace large static models. More importantly, the BVH can be used to ray trace deformable models (sets of triangles whose positions change over time) with little loss of performance. A variety of efficiency techniques are used to achieve this performance, but three algorithmic changes to the typical BVH algorithm are mainly responsible. First, the BVH is built using a variant of the surface area heuristic conventionally used to build kdtrees. Second, the topology of the BVH is not changed over time so that only the bounding volumes need to be refit from frametoframe. Third, and most importantly, packets of rays are traced together through the BVH using a novel integrated packetfrustum traversal scheme. This traversal scheme elegantly combines the advantages of both packet traversal and frustum traversal and allows for rapid hierarchy descent for packets that hit bounding volumes as well as rapid exits for packets that miss. A BVHbased ray tracing system using these techniques is shown to achieve performance for deformable models comparable to that previously available only for static models.
A Beam Tracing Approach to Acoustic Modeling for Interactive Virtual Environments
, 1998
"... Virtual environment research has focused on interactive image generation and has largely ignored acoustic modeling for spatialization of sound. Yet, realistic auditory cues can complement and enhance visual cues to aid navigation, comprehension, and sense of presence in virtual environments. A prima ..."
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Cited by 72 (13 self)
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Virtual environment research has focused on interactive image generation and has largely ignored acoustic modeling for spatialization of sound. Yet, realistic auditory cues can complement and enhance visual cues to aid navigation, comprehension, and sense of presence in virtual environments. A primary challenge in acoustic modeling is computation of reverberation paths from sound sources fast enough for realtime auralization. We have developed a system that uses precomputed spatial subdivision and "beam tree" data structures to enable realtime acoustic modeling and auralization in interactive virtual environments. The spatial subdivision is a partition of 3D space into convex polyhedral regions (cells) represented as a cell adjacency graph. A beam tracing algorithm recursively traces pyramidal beams through the spatial subdivision to construct a beam tree data structure representing the regions of space reachable by each potential sequence of transmission and specular reflection even...
Theory and Application of Specular Path Perturbation
, 2000
"... In this paper we apply perturbation methods to the problem of computing specular reflections in curved surfaces. The key idea is to generate families of closely related optical paths by expanding a given path into a highdimensional Taylor series. Our path perturbation method is based on closedform ..."
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Cited by 27 (2 self)
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In this paper we apply perturbation methods to the problem of computing specular reflections in curved surfaces. The key idea is to generate families of closely related optical paths by expanding a given path into a highdimensional Taylor series. Our path perturbation method is based on closedform expressions for linear and higherorder approximations of ray paths, which are derived using Fermat's Variation Principle and the Implicit Function Theorem. The perturbation formula presented here holds for general multiplebounce reflection paths and provides a mathematical foundation for exploiting path coherence in ray tracing acceleration techniques and incremental rendering. To illustrate its use, we describe an algorithm for fast approximation of specular reflections on curved surfaces; the resulting images are of high accuracy and nearly indistinguishable from ray traced images. Keywords: perturbation theory, implicit surfaces, optics, ray tracing, specular reflection 1 1 Introduct...
S.: SecondDepth Shadow Mapping
, 1994
"... Depthmap algorithms for rendering antialiased shadows are computationally efficient and accommodate a wide variety of primitives. They have two drawbacks, however, that make them impractical for everyday use: They require the user to specify a bias that must be optimized for each particular scene a ..."
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Cited by 20 (0 self)
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Depthmap algorithms for rendering antialiased shadows are computationally efficient and accommodate a wide variety of primitives. They have two drawbacks, however, that make them impractical for everyday use: They require the user to specify a bias that must be optimized for each particular scene and view; and they generally require the use of large shadow maps— frequently much larger than the final image that is to be rendered. This paper presents an improved depthmap shadow algorithm that does not require a bias for scenes composed of solids and produces accurate shadows with smaller depth maps. It consists of two novel changes to the basic depthmap algorithm. First, the depth map samples the depth values of surfaces that are second nearest the light source. Second, virtual samples are created on local tangent planes of surfaces that are visible from the camera's point of view to match real samples of the depth map. These two changes allow depth comparisons to be done accurately and without the need for a compensating bias value. They also allow the algorithm to produce superior results when using small depth maps. The new algorithm incorporates percentagecloser filtering to antialias shadow boundaries and can be accelerated using zbuffer hardware in the same manner as previous algorithms. 1
OctreeR: an Adaptive Octree for Efficient Ray Tracing
 IEEE TVCG
, 1995
"... AbstractRay tracing requires many rayobect intersection tests. A way of reducing the number of rayobject intersection tests is to subdivide the space occupied by objects into many nonoverlapping subregions, called voxels, and to construct an octree for the subdivided space. In this paper, we prop ..."
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Cited by 17 (0 self)
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AbstractRay tracing requires many rayobect intersection tests. A way of reducing the number of rayobject intersection tests is to subdivide the space occupied by objects into many nonoverlapping subregions, called voxels, and to construct an octree for the subdivided space. In this paper, we propose the OctreeR, an octreevariant data structure for efficient ray tracing. The algorithm for constructing the OctreeR first estimates the number of rayobject intersection tests. Then, it partitions the space along the plane that minimizes the estimated number of rayobject intersection tests. We present the results of experiments for verifying the effectiveness of the OctreeR. In the experiment, the OctreeR provides a 4 % to 47 % performance gain over the conventional octree. The result shows the more skewed the object distribution (as is typical for real data), the more performance gain the OctreeR achieves. Index TermsRay tracing octree, OctreeR, space subdivision. I.
Visible Zone Maintenance for RealTime Occlusion Culling
"... Interactive rendering of a large, dense environment can be accelerated by keeping track of the visible objects. We introduce a framework for maintaining the visible set that provides perfect occluder fusion while taking advantage of temporal coherence in the observer 's position. The method is based ..."
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Cited by 5 (0 self)
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Interactive rendering of a large, dense environment can be accelerated by keeping track of the visible objects. We introduce a framework for maintaining the visible set that provides perfect occluder fusion while taking advantage of temporal coherence in the observer 's position. The method is based on maintaining a visible zone, a spatial decomposition that supports fast visibility queries and efficient updates. We discuss visible zone maintenance in 2 and 2.5 dimensions, and present extensions to maintain conservative visibility for complex geometry. We present results from an interactive flythrough of a forest environment with one million trees and seven billion polygons.