Claudio T. Silva, Joseph S. B. Mitchell, and Arie E. Kaufman. Automatic generation of triangular irregular networks using greedy cuts. In Proc. Visualization '95. IEEE Comput. Soc. Press, 1995.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....results, but their implementation was somewhat restricted by the requirement of several independent objects. Terrains are one large object, and therefore this approach is not directly applicable to terrain visualization. Silva, Mitchell, and Kaufman used these heuristics in a different approach [2]. They designed a system capable of generating triangular meshes from a uniform rectilinear heightfield at any detail level. Given an error threshold, they could simplify the mesh greatly into several irregular triangles. Unfortunately, the method was slow (anywhere from 3 30 seconds) so it had ....

Claudio T. Silva, Joseph S. B. Mitchell, and Arie E. Kaufman. Automatic generation of triangular irregular networks using greedy cuts. In Proc. Visualization 95, pages 201-208, IEEE Computing Society Press, 1995.

....views of interest are from the exterior, and the majority of scene surfaces are visible at all times. Thus visibility culling is not applicable. Among LOD algorithms are techniques that construct a triangular mesh that closely approximates a terrain surface while minimizing the number of triangles [22, 26, 28], adaptive subdivision to fit a set of polygons to a surface [5] and decimation to remove vertices[7, 24] Approaches that decide when to use the simplified models include a method to maintain a minimum frame rate while providing the best possible image [7] using distance from the viewpoint as a ....

Silva, C., Mitchell, J., Kaufman, A., "Automatic Generation of Triangular Irregular Networks Using Greedy Cuts," Visualization `95, pp. 201-208, 1995

.... insertion and deletion approaches have 2 been explored by many researchers for application in Geographical Information Systems (GIS) A common technique is to extract key points of data from the originally dense set of points, and compute a Delaunay triangulation [7,11,12,33,39,41] Silva et al. [37] use a greedy approach for inserting points into an initially sparse mesh. Schroeder et al. 36] compute reduced representations for dense triangular surface meshes such as those computed by Marching Cubes [25] or similar isosurfacing algorithms. Vertices in the dense mesh are examined and ....

C. Silva, J. S. B. Mitchell, and A. E. Kaufman. Automatic generation of triangular irregular networks using greedy cuts. In G. M. Nielson and D. Silver, editors, Proceedings of IEEE Visualization '95, pages 201--208, October 1995.

....Delaunay or data dependent triangulation. Chen and Schmitt found that data dependent triangulation simplified better on surfaces with a preferred direction, such as cylinders. Silva Mitchell Kaufman 95. A rather different approach to height field triangulation was proposed by Silva et al. [117]. We classify it here as a refinement method, although it is different in spirit from the previous methods. Their method uses greedy cuts, triangulating the domain from the perimeter inward, on each pass biting out of the perimeter the triangle of largest area that fits the input data within a ....

Claudio T. Silva, Joseph S. B. Mitchell, and Arie E. Kaufman. Automatic generation of triangular irregular networks using greedy cuts. In Proc. Visualization '95. IEEE Comput. Soc. Press, 1995. http://www.cs.sunysb.edu:80/ #csilva/claudio-papers.html.

....arithmetic, and Shewchuk s design and implementation [43] of four predicates based on adaptive floating point arithmetic. See the recent survey papers by Yap and Dub e [49, 50] Exact arithmetic is offered by the geometric software packages LEDA [13, 33] and CGAL [23, 38] Recently, Silva et al. [45] used an approach similar in spirit to the one described in this paper for ensuring reliability. While not addressing the robustness issue directly, they also describe how a carefully tailored ear clipping algorithm, combined with some additional heuristics, has yielded a fairly reliable and ....

C. Silva, J.S.B. Mitchell, and A.E. Kaufman. Automatic Generation of Triangular Irregular Networks Using Greedy Cuts. In Visualization '95, pages 201--208, San Jose, CA, USA, 1995. IEEE Comput. Society Press.

....interactively is to compute a reduced model in which large triangles replace groups of small triangles which are nearly co planar. Related work on planar meshes with scalar data at the nodes aims to reduce the size of the mesh required to represent the scalar field to a defined level of fidelity [2, 3, 4, 8, 12, 16, 17, 19]. By taking advantage of the special case presented by a height map, various algorithms have been developed which create triangular surface approximations while maintaining a user defined bound on the introduced error. In visualizing scientific data, it is quite often not only geometry that the ....

....Geographical Information Systems (GIS) researchers interested in reducing the complexity of dense Digital Elevation Models (DEMs) A common technique is to extract key points of data from the originally dense set of points, and compute a Delaunay triangulation [2, 3, 4, 12, 17, 19] Silva, et. al[16] use a greedy method for inserting points into an initially sparse mesh. A survey by Lee [8] reviews methods for computing reduced meshes by both point insertion and point deletion. Geometric mesh reduction has been approached from several directions. In reduction of polygonal models, Turk [18] ....

C. Silva, J. Mitchell, and A. Kaufman. Automatic generation of triangular irregular networks using greedy cuts. In G. M. Nielson and D. Silver, editors, Visualization '95 Proceedings, pages 201--208, October 1995.

....too slow or inaccurate for practical use for large datasets. This chapter is based on work published in [112] In Chapter 5, we describe a parallelization scheme of our algorithm to render irregular grids. Our preliminary results on the simplification of irregular grids is presented in Chapter 6 [111], where we introduce the Greedy Cuts triangulation technique and describe its implementation for the case of height field terrains. CHAPTER 1. INTRODUCTION 7 The PVR system, described in Chapter 7, serves as our testbed for most of our work. PVR is a state of the art parallel rendering system ....

C. Silva, J. Mitchell, and A. Kaufman. Automatic generation of triangular irregular networks using greedy cuts. In IEEE Visualization '95, pages 201--208, 1995.

....reduction: A driving application for reduction of height fields is GIS. A wide range of techniques are based on extraction of key points or edges from the originally dense set of points, followed by a constrained Delaunay triangulation [DFP85, FFNP84, FL79, PDDT94, Tsa93, WJ92] Silva, et. al [SMK95] uses a greedy method for inserting points into an initially sparse mesh, reporting both better and faster reduction compared to a freely available terrain reduction tool. A survey by Lee [Lee91] reviews methods for computing reduced meshes by both point insertion and point deletion. Bajaj and ....

C. Silva, J. Mitchell, and A. E. Kaufman. Automatic generation of triangular irregular networks using greedy cuts. In G. M. Nielson and D. Silver, editors, Visualization '95 Proceedings, pages 201--208, 1995.

....implementation is hardly feasible in practice; however, a simplified implementation of the latter algorithm has given empirical results that are comparable to those obtained with other methods. An algorithm that solves the first problem with a greedy technique has been proposed by Silva et al. [Sil95]. The approximate TIN is built incrementally by iteratively cutting triangles (ears or bites) from hollow polygons that span the domain: at each step the algorithm considers a polygon, and bites from it a triangle of maximal area that is compatible with the required accuracy. It is conjectured in ....

Silva, C.T., Mitchell, J.S.B., Kaufman, A.E., Automatic generation of triangular irregular networks using greedy cuts, Proceedings IEEE Visualization'95, 1995, pp.201-208.

.... start with a single triangle (or tetrahedron for general surfaces) and refine it locally until the resulting surface becomes an approximation, or they start with a fine triangulation and coarsen it locally (by removing a vertex and filling the hole) until one can no longer remove a vertex [12, 13, 14, 15, 17, 16, 27, 33, 34, 36, 38]. The former method is called refinement, and the latter is called decimation. Some other approaches that extend to arbitrary surfaces have also been proposed. They include an optimization method that formulates the problem as an energy optimization problem [28, 29] and an approach based on ....

....together the triangles by computing the constrained Delaunay triangulation of the edges of the simplicial partition, and thus obtain a valid triangulation of the plane. Our implementation has about 2000 lines of C code. All the input data sets consisted of 120 Theta 120 elevation arrays, as in [38]. We ran our experiments on a Digital AlphaStation 500 266 workstation, and each of them took between 30 and 45 seconds. In the Table 1, we summarize our results and compare them with the results of Franklin [23] and Silva, et al. 38] on the same data sets. The column SP A gives the number of ....

[Article contains additional citation context not shown here]

C. T. Silva, J, S. B. Mitchell, and A. E. Kaufman, Automatic generation of triangular irregular networks using greedy cuts, Proc. Visualization '95, 1995, 201--208.

....arithmetic, and Shewchuk s design and implementation [42] of four predicates based on adaptive floating point arithmetic. See the recent survey papers by Yap and Dub e [49, 48] Exact arithmetic is offered by the geometric software packages LEDA [14, 32] and CGAL [23, 37] Recently, Silva et al. [44] have used an approach similar in spirit to the one described in this paper for ensuring reliability. While not addressing the robustness issue directly, they also describe how a carefully tailored ear clipping algorithm, combined with some additional heuristics, has yielded a fairly reliable and ....

C. Silva, J.S.B. Mitchell, and A.E. Kaufman. Automatic Generation of Triangular Irregular Networks Using Greedy Cuts. In Visualization '95, pages 201--208, San Jose, CA, USA, 1995. IEEE Comput. Society Press.

....corresponding original terrains. In Section 5 we report on some of our experiments with VPTS, as well as with three other software packages implementing simplification methods that were developed for the standard maximum vertical di#erence measure. These other packages are Terra ( 10] GcTin ([15, 14]) and QSlim ( 9] Our choice of packages is based on what has been readily available for download; we plan to extend our experiments to include other packages as well. In our experiments we consider several di#erent input scenes, each a detailed terrain representing a geographic region. For ....

....vertices in the approximations. Notice the di#erence in the distribution of the vertices due to the emphasis put by VPTS on ridges. 5. EXPERIMENTAL RESULTS In this section we report on some of our experiments with VPTS, as well as comparisons with three other software packages (Terra [10] GcTin [15, 14], and QSlim [9] that implement simplification methods developed for the standard maximum vertical di#erence measure. 5.1 Methods for comparison Terra. This algorithm, implemented by Garland [10] is based on a simple greedy insertion algorithm with some optimizations to make it run faster. The ....

[Article contains additional citation context not shown here]

C. T. Silva, J. S. B. Mitchell, and A. E. Kaufman. Automatic generation of triangular irregular networks using greedy cuts. In Visualization 95, pages 201--208, San Jose CA, 1995. IEEE Computer Society Press.

....corresponding original terrains. In Section 5 we report on some of our experiments with VPTS, as well as with three other software packages implementing simpli cation methods that were developed for the standard maximum vertical di erence measure. These other packages are Terra ( 13] GcTin ([18, 17]) and QSlim ( 12] In our experiments we consider several di erent input scenes, each a detailed terrain representing a geographic region. For each of the scenes T , we apply our new method, together with the three other methods for comparison, with various degrees of simpli cation speci ....

....vertices in the approximations. Notice the di erence in the distribution of the vertices due to the emphasis put by VPTS on ridges. 5 Experimental Results In this section we report on some of our experiments with VPTS, as well as comparisons with three other software packages (Terra [13] GcTin [18, 17], and QSlim [12] that implement simpli cation methods developed for the standard maximum vertical di erence measure. 8 test no. of antennas range in km no. of receivers (r1 ; r2) per antenna t1 30 2 2.5 30 Table 1: The tests. 5.1 Methods for comparison Terra. This algorithm, ....

[Article contains additional citation context not shown here]

C. T. Silva, J. S. B. Mitchell, and A. E. Kaufman. Automatic generation of triangular irregular networks using greedy cuts. In Visualization 95, pages 201-208, San Jose CA, 1995. IEEE Computer Society Press.

....with respect to n or m (but ideally both) The memory dependency on n affects the usefulness of a given algorithm in the sense that it limits the size of models that can be simplified. In general the memory requirement of a given algorithm grows with both m and n (for exceptions, see e.g. [29, 30]) The dependency on m has direct implications on the maximum accuracy of the approximation. As an example, an efficient terrain simplification algorithm is presented in [13] whose memory complexity is analyzed to be 3n 192m bytes, where n and m are the number of vertices in the input and output, ....

C. Silva, J. Mitchell, and A. E. Kaufman. Automatic Generation of Triangular Irregular Networks Using Greedy Cuts. IEEE Visualization '95, pages 201--208, November 1995.

....the output triangulation, while still respecting the error bounds. The method also readily permits one to partition the data, possibly specifying a different error bound in different regions of the terrain; this may be useful in applications requiring real time triangulation. In a predecessor [9] to this paper, we developed an advancing front algorithm and its implementation (GcTin) While the algorithm was shown to have favorable properties in terms of memory consumption and total number of triangles, it was much less effective at producing high quality triangulations from the point of ....

....the terrain on R, such that the TIN has few triangles, the triangles are of good quality, and the TIN represents a surface that is e close to that represented by H#x;y#. 2 Review of Greedy Cuts This section gives a high level description of the Greedy Cuts method as originally proposed in [9]. The algorithm maintains a list of untriangulated simple polygons, P , which represent the portion of R over which no triangulated surface has yet been constructed. At each step, our goal is to select a large triangle T within one of the polygons P 2 P , such that (1) the vertices v 1 =#x 1 ....

[Article contains additional citation context not shown here]

C. Silva, J. Mitchell, and A. Kaufman. Automatic generation of triangular irregular networks using greedy cuts. Proc. IEEE

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Claudio T. Silva, Joseph S. B. Mitchell, and Arie E. Kaufman. Automatic generation of triangular irregular networks using greedy cuts. In Proc. Visualization '95. IEEE Comput. Soc. Press, 1995.

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Claudio T. Silva, Joseph S. B. Mitchell, and Arie E. Kaufman. Automatic generation of triangular irregular networks using greedy cuts. In Proc. Visualization '95. IEEE Comput. Soc. Press, 1995.

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Claudio T. Silva, Joseph S. B. Mitchell, and Arie E. Kaufman. Automatic generation of triangular irregular networks using greedy cuts. In Proc. Visualization '95. IEEE Comput. Soc. Press, 1995.

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