Results 1  10
of
16
Fast Isocontouring for Improved Interactivity
 In Proceedings of 1996 Symposium on Volume Visualization
, 1996
"... We present an isocontouringalgorithm which is nearoptimal for realtime interaction and modification of isovalues in large datasets. A preprocessing step selects a subset S of the cells which are considered as seed cells. Given a particular isovalue, all cells in S which intersect the given isocont ..."
Abstract

Cited by 123 (32 self)
 Add to MetaCart
(Show Context)
We present an isocontouringalgorithm which is nearoptimal for realtime interaction and modification of isovalues in large datasets. A preprocessing step selects a subset S of the cells which are considered as seed cells. Given a particular isovalue, all cells in S which intersect the given isocontour are extracted using a highperformance range search. Each connected component is swept out using a fast isocontour propagation algorithm. The computational complexity for the repeated action of seed point selection and isocontour propagation is O(logn 0 + k), where n 0 is the size of S and k is the size of the output. In the worst case, n 0 = O(n), where n is the number of cells, while in practical cases, n 0 is smaller than n by one to two orders of magnitude. The general case of seed set construction for a convex complex of cells is described, in addition to a specialized algorithm suitable for meshes of regular topology, including rectilinear and curvilinear meshes. Keyword...
Speeding up isosurface extraction using interval trees
 IEEE Transactions on Visualization and Computer Graphics
, 1997
"... ..."
(Show Context)
Optimal Isosurface Extraction from Irregular Volume Data (Addendum)
, 1996
"... This document is available in .ps format at our web site (http://miles.cnuce.cnr.it/cg/bibliography.html). This workwas partially founded by the Progetto Coordinato "Modelli multirisoluzione per la visualizzazione di campi scalari multidimensionali" of the Italian National Research Council ..."
Abstract

Cited by 64 (5 self)
 Add to MetaCart
This document is available in .ps format at our web site (http://miles.cnuce.cnr.it/cg/bibliography.html). This workwas partially founded by the Progetto Coordinato "Modelli multirisoluzione per la visualizzazione di campi scalari multidimensionali" of the Italian National Research Council (CNR). We wish to thank those who have made available on the public domain the datasets used in the evaluation of the proposed techniques. References
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 51 (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
I/Oefficient algorithms for contourline extraction and planar graph blocking (Extended Abstract)
 IN PROCEEDINGS OF THE 10TH ACMSIAM SYMPOSIUM ON DISCRETE ALGORITHMS
, 1998
"... For a polyhedral terrain \Sigma, the contour at zcoordinate h, denoted Ch , is defined to be the intersection of the plane z = h with \Sigma. In this paper, we study the contourline extraction problem, where we want to preprocess \Sigma into a data structure so that given a query zcoordinate h, ..."
Abstract

Cited by 19 (1 self)
 Add to MetaCart
For a polyhedral terrain \Sigma, the contour at zcoordinate h, denoted Ch , is defined to be the intersection of the plane z = h with \Sigma. In this paper, we study the contourline extraction problem, where we want to preprocess \Sigma into a data structure so that given a query zcoordinate h, we can report Ch quickly. This is a central problem that arises in geographic information systems (GIS), where terrains are often stored as Triangular Irregular Networks (TINs). We present an I/Ooptimal algorithm for this problem which stores a terrain \Sigma with N vertices using O(N=B) blocks, where B is the size of a disk block, so that for any query h, the contour Ch can be computed using O(log B N + jCh j=B) I/O operations, where jCh j denotes the size of Ch .
Topological manipulation of isosurfaces
, 2004
"... In this thesis, I show how to use the topological information encoded in an abstraction called the contour tree to enable interactive manipulation of individual contour surfaces in an isosurface scene, using an interface called the flexible isosurface. Underpinning this interface are several improve ..."
Abstract

Cited by 15 (2 self)
 Add to MetaCart
In this thesis, I show how to use the topological information encoded in an abstraction called the contour tree to enable interactive manipulation of individual contour surfaces in an isosurface scene, using an interface called the flexible isosurface. Underpinning this interface are several improvements and extensions to existing work on the contour tree. The first, and most critical, extension, is the path seed: a new method of generating seeds from the contour tree for isosurface extraction. The second extension is to compute geometric information called local spatial measures for contours and store this information in the contour tree. The third extension is to use local spatial measures to simplify both the contour tree and isosurface displays. This simplification can also be used for noise removal. Lastly, this thesis extends work with contour trees from simplicial meshes to arbitrary meshes, interpolants, and tessellation cases. ii Contents ii
Seed sets and search structures for optimal isocontour extraction
 Texas Institute of Computational and Applied Mathematics
, 1999
"... The search for intersected cells in isocontouring can be accelerated using suitable range query data structures, such as the interval tree or segment tree. The storage overhead of such search structures can be significantly reduced by searching over a subset of the cells Ë, called a seed set, which ..."
Abstract

Cited by 8 (1 self)
 Add to MetaCart
(Show Context)
The search for intersected cells in isocontouring can be accelerated using suitable range query data structures, such as the interval tree or segment tree. The storage overhead of such search structures can be significantly reduced by searching over a subset of the cells Ë, called a seed set, which contains at least one cell per connected component of every isocontour. We present three algorithms for generating seed sets and compare their time complexity and performance in terms of the number of seed cells generated. The first two algorithms are applicable to both regular and irregular grids of arbitrary dimension, while the third is a specialization for regular grids. The first algorithm produces a nearly optimal seed set, minimizing the storage overhead for the search structure. While the second and third algorithms may produce a larger seed set, they are extremely fast, have the advantage of being suitable for extremely large datasets that cannot be kept in main memory (outofcore computation), and are amenable to parallelization. In each case the resulting seed sets are orders of magnitude smaller than the total number of cells, while the computational complexity remains optimal. We compare the results of the two new algorithms with previous results and recent new work. 2
Two Topics in Applied Algorithmics
, 1998
"... This thesis examines two largely unrelated problems in applied algorithmics, motivated by the search for efficient geometric algorithms. In the first part of the thesis, we consider the problem of finding efficient parallel algorithms for heterogeneous parallel computers, i.e., parallel computers in ..."
Abstract

Cited by 6 (0 self)
 Add to MetaCart
(Show Context)
This thesis examines two largely unrelated problems in applied algorithmics, motivated by the search for efficient geometric algorithms. In the first part of the thesis, we consider the problem of finding efficient parallel algorithms for heterogeneous parallel computers, i.e., parallel computers in which different processors have different computational potential. To this end, we define a formal computational model for heterogeneous systems and develop algorithms for commonly used communication operations. The result is that many existing parallel algorithms which use these communication operations can be adapted to our model with little or no modifications. In the second part of the thesis we consider the problem of geometric models which allow for varying levels of detail. To this end, we extend the progressive mesh representation introduced by Hoppe. The main technical contribution of this part is an efficient scheme for refining only selected regions of a progressive mesh. Using ...
Isosurface Extraction in Large Scientific Visualization Applications Using the I/Ofilter Technique
, 1998
"... For large scientific visualization applications, it is often impossible to hold the entire datasets in main memory, even on supercomputers. Previously, we proposed the I/Ofilter technique, which is the first I/Ooptimal method for the problem of isosurface extraction in scientific visualization. I/ ..."
Abstract

Cited by 4 (3 self)
 Add to MetaCart
For large scientific visualization applications, it is often impossible to hold the entire datasets in main memory, even on supercomputers. Previously, we proposed the I/Ofilter technique, which is the first I/Ooptimal method for the problem of isosurface extraction in scientific visualization. I/Ofilter works by indexing and reorganizing the datasets in disk, so that isosurface can be extracted with a very small amount of disk I/O's. The main advantage of this approach is that datasets much larger than main memory can be visualized very efficiently, possibly even on lowend machines. The original I/Ofilter technique uses the I/Ooptimal interval tree of Arge and Vitter as the indexing data structure, together with the isosurface engine from Vtk (one of the currently best visualization packages). The main shortcoming of this approach was the overheads of the disk scratch space and the preprocessing time necessary to build the data structure, and of the disk space needed to hold th...
Isocontour based Visualization of Timevarying Scalar Fields
"... Timevarying scalar fields are produced by measurements or simulation of physical processes over time, and must be interpreted with the assistance of computational tools. A useful tool in interpreting the data is graphical visualization, often through level sets, or isocontours of a continuous funct ..."
Abstract

Cited by 2 (0 self)
 Add to MetaCart
Timevarying scalar fields are produced by measurements or simulation of physical processes over time, and must be interpreted with the assistance of computational tools. A useful tool in interpreting the data is graphical visualization, often through level sets, or isocontours of a continuous function derived from the data. In this paper we survey isocontour based visualization techniques for timevarying scalar fields. We focus on techniques that aid selection of meaningful isocontours, and algorithms to extract chosen isocontours.