Results 1  10
of
88
The Contour Spectrum
, 1997
"... We introduce the contour spectrum, a user interface component that improves qualitative user interaction and provides realtime exact quantification in the visualization of isocontours. The contour spectrum is a signature consisting of a variety of scalar data and contour attributes, computed over t ..."
Abstract

Cited by 156 (27 self)
 Add to MetaCart
We introduce the contour spectrum, a user interface component that improves qualitative user interaction and provides realtime exact quantification in the visualization of isocontours. The contour spectrum is a signature consisting of a variety of scalar data and contour attributes, computed over the range of scalar values w 2!.We explore the use of surface area, volume, and gradientintegral of the contour that are shown to be univariate Bspline functions of the scalar value w for multidimensional unstructured triangular grids. These quantitative properties are calculated in realtime and presented to the user as a collection of signature graphs (plots of functions of w) to assist in selecting relevant isovalues w 0 for informative visualization. For timevarying data, these quantitative properties can also be computed over time, and displayed using a 2D interface, giving the user an overview of the timevarying function, and allowing interaction in both isovalue and timestep. The effectiveness of the current system and potential extensions are discussed.
Contour Trees and Small Seed Sets for Isosurface Traversal
, 1997
"... For 2D or 3D meshes that represent a continuous function to the reals, the contoursor isosurfacesof a specified value are an important way to visualize it. To find such contours, a seed set can be used for the starting points from which the traversal of the contours can start. This paper gives ..."
Abstract

Cited by 119 (19 self)
 Add to MetaCart
For 2D or 3D meshes that represent a continuous function to the reals, the contoursor isosurfacesof a specified value are an important way to visualize it. To find such contours, a seed set can be used for the starting points from which the traversal of the contours can start. This paper gives the first methods to obtain seed sets that are provably small in size. They are based on a variant of the contour tree (or topographic change tree). We give a new, simple algorithm to compute such a tree in regular and irregular meshes that requires O(n log n) time in 2D for meshes with n elements, and in O(n 2 ) time in higher dimensions. The additional storage overhead is proportial to the maximum size of any contour (linear in the worst case, but typically less). Given the contour tree, a minimum size seed set can be computed in polynomial time and storage. Since in practice at most linear storage is allowed, we develop a simple approximation algorithm giving a seed set of size at most...
MorseSmale Complexes for Piecewise Linear 3Manifolds
, 2003
"... We define the MorseSmale complex of a Morse function over a 3manifold as the overlay of the descending and ascending manifolds of all critical points. In the generic case, its 3dimensional cells are shaped like crystals and are separated by quadrangular faces. In this paper, we give a combinatori ..."
Abstract

Cited by 105 (28 self)
 Add to MetaCart
We define the MorseSmale complex of a Morse function over a 3manifold as the overlay of the descending and ascending manifolds of all critical points. In the generic case, its 3dimensional cells are shaped like crystals and are separated by quadrangular faces. In this paper, we give a combinatorial algorithm for constructing such complexes for piecewise linear data.
Speeding Up Isosurface Extraction using Interval Trees
, 1997
"... The interval tree is an optimally efficient search structure proposed by Edelsbrunner [5] to retrieve intervals of the real line that contain a given query value. We propose the application of such a data structure to the fast location of cells intersected by an isosurface in a volume dataset. The r ..."
Abstract

Cited by 104 (4 self)
 Add to MetaCart
The interval tree is an optimally efficient search structure proposed by Edelsbrunner [5] to retrieve intervals of the real line that contain a given query value. We propose the application of such a data structure to the fast location of cells intersected by an isosurface in a volume dataset. The resulting search method can be applied to both structured and unstructured volume datasets, and it can be applied incrementally to exploit coherence between isosurfaces. We also address issues about storage requirements, and operations other than the location of cells, whose impact is relevant in the whole isosurface extraction task. In the case of unstructured grids, the overhead due to the search structure is compatible with the storage cost of the dataset, and local coherence in the computation of isosurface patches is exploited through a hash table. In the case of a structured dataset, a new conceptual organization is adopted, called the chessboard approach, wich exploits the regular str...
HardwareAccelerated Volume and Isosurface Rendering Based on CellProjection
, 2000
"... We present two beneficial rendering extensions to the Projected Tetrahedra (PT) algorithm by Shirley and Tuchman. These extensions are compatible with any cell sorting technique, for example the BSPXMPVO sorting algorithm for unstructured meshes. ..."
Abstract

Cited by 88 (13 self)
 Add to MetaCart
We present two beneficial rendering extensions to the Projected Tetrahedra (PT) algorithm by Shirley and Tuchman. These extensions are compatible with any cell sorting technique, for example the BSPXMPVO sorting algorithm for unstructured meshes.
Interactive OutOfCore Isosurface Extraction
"... In this paper, we present a novel outofcore technique for the interactive computation of isosurfaces from volume data. Our algorithm minimizes the main memory and disk space requirements on the visualization workstation, while speeding up isosurface extraction queries. Our overall approach is a tw ..."
Abstract

Cited by 85 (18 self)
 Add to MetaCart
In this paper, we present a novel outofcore technique for the interactive computation of isosurfaces from volume data. Our algorithm minimizes the main memory and disk space requirements on the visualization workstation, while speeding up isosurface extraction queries. Our overall approach is a twolevel indexing scheme. First, by our metacell technique, we partition the original dataset into clusters of cells, called metacells. Secondly, we produce metaintervals associated with the metacells, and build an indexing data structure on the metaintervals. We separate the cell information, kept only in metacells in disk, from the indexing structure, which is also in disk and only contains pointers to metacells. Our metacell technique is an I/Oefficient approach for computing a kdtreelike partition of the dataset. Our indexing data structure, the binaryblocked I/O interval tree, is a new I/Ooptimal data structure to perform stabbing queries that report from a set of metainte...
I/O Optimal Isosurface Extraction
, 1997
"... In this paper we give I/Ooptimal techniques for the extraction of isosurfaces from volumetric data, by a novel application of the I/Ooptimal interval tree of Arge and Vitter. The main idea is to preprocess the dataset once and for all to build an efficient search structure in disk, and then each ti ..."
Abstract

Cited by 73 (17 self)
 Add to MetaCart
In this paper we give I/Ooptimal techniques for the extraction of isosurfaces from volumetric data, by a novel application of the I/Ooptimal interval tree of Arge and Vitter. The main idea is to preprocess the dataset once and for all to build an efficient search structure in disk, and then each time we want to extract an isosurface, we perform an outputsensitive query on the search structure to retrieve only those active cells that are intersected by the isosurface. During the query operation, only two blocks of main memory space are needed, and only those active cells are brought into the main memory, plus some negligible overhead of disk accesses. This implies that we can efficiently visualize very large datasets on workstations with just enough main memory to hold the isosurfaces themselves. The implementation is delicate but not complicated. We give the first implementation of the I/Ooptimal interval tree, and also implement our methods as an I/O filter for Vtk's isosurface ext...
Parallel Accelerated Isocontouring for OutofCore Visualization
 In Proceedings of the 1999 IEEE Symposium on Parallel Visualization and Graphics
, 1999
"... In this paper we introduce a scheme for static analysis that allows us to partition large geometric datasets at multiple levels of granularity to achieve both load balancing in parallel computations and minimal access to secondary memory in outofcore computations. The idea is illustrated and fully ..."
Abstract

Cited by 49 (13 self)
 Add to MetaCart
In this paper we introduce a scheme for static analysis that allows us to partition large geometric datasets at multiple levels of granularity to achieve both load balancing in parallel computations and minimal access to secondary memory in outofcore computations. The idea is illustrated and fully exploited for the case of isosurface extraction, but extendible to a class of algorithms based on a small set of algorithm parameters and for which an appropriate static analysis can be performed. 1
Outofcore algorithms for scientific visualization and computer graphics
 In Visualization’02 Course Notes
, 2002
"... Recently, several external memory techniques have been developed for a wide variety of graphics and visualization problems, including surface simplification, volume rendering, isosurface generation, ray tracing, surface reconstruction, and so on. This work has had significant impact given that in re ..."
Abstract

Cited by 46 (11 self)
 Add to MetaCart
Recently, several external memory techniques have been developed for a wide variety of graphics and visualization problems, including surface simplification, volume rendering, isosurface generation, ray tracing, surface reconstruction, and so on. This work has had significant impact given that in recent years there has been a rapid increase in the raw size of datasets. Several technological trends are contributing to this, such as the development of highresolution 3D scanners, and the need to visualize ASCIsize (Accelerated Strategic Computing Initiative) datasets. Another important push for this kind of technology is the growing speed gap between main memory and caches, which penalizes algorithms that do not optimize for coherence of access. Because of these reasons, much research in computer graphics focuses on developing outofcore (and often cachefriendly) techniques. This paper surveys fundamental issues, current problems, and unresolved questions, and aims to provide graphics researchers and professionals with an effective knowledge of current techniques, as well as the foundation to develop novel techniques on their own. Keywords: Outofcore algorithms, scientific visualization, computer graphics, interactive rendering, volume rendering, surface simplification.
Isosurface Computation Made Simple: Hardware Acceleration, Adaptive Refinement and Tetrahedral Stripping
 In Joint Eurographics  IEEE TVCG Symposium on Visualization (VisSym
, 2004
"... This paper presents a simple approach for rendering isosurfaces of a scalar field. Using the vertex programming capability of commodity graphics cards, we transfer the cost of computing an isosurface from the Central Processing Unit (CPU), running the main application, to the Graphics Processing U ..."
Abstract

Cited by 44 (2 self)
 Add to MetaCart
This paper presents a simple approach for rendering isosurfaces of a scalar field. Using the vertex programming capability of commodity graphics cards, we transfer the cost of computing an isosurface from the Central Processing Unit (CPU), running the main application, to the Graphics Processing Unit (GPU), rendering the images. We consider a tetrahedral decomposition of the domain and draw one quadrangle (quad) primitive per tetrahedron. A vertex program transforms the quad into the piece of isosurface within the tetrahedron (see Figure 2). In this way, the main application is only devoted to streaming the vertices of the tetrahedra from main memory to the graphics card. For adaptively refined rectilinear grids, the optimization of this streaming process leads to the definition of a new 3D spacefilling curve, which generalizes the 2D Sierpinski curve used for efficient rendering of triangulated terrains. We maintain the simplicity of the scheme when constructing viewdependent adaptive refinements of the domain mesh. In particular, we guarantee the absence of Tjunctions by satisfying local bounds in our nested error basis. The expensive stage of fixing cracks in the mesh is completely avoided. We discuss practical tradeoffs in the distribution of the workload between the application and the graphics hardware. With current GPU's it is convenient to perform certain computations on the main CPU. Beyond the performance considerations that will change with the new generations of GPU's this approach has the major advantage of avoiding completely the storage in memory of the isosurface vertices and triangles.