Yi-Jen Chiang

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Michael T. GoodrichjS Edward F. Grovefll Roberto Tamassia*t Darren Erik Vengrofftt Jeffrey Scott Vitterqt We present a collection of new techniques for designing and analyzing efficient external-memory algorithms for graph problems and illustrate how these techniques can be applied to a wide variety of specific problems. Our results include:(More)
In this paper, we propose a novel external-memory algorithm to support view-dependent simplification for datasets much larger than main memory. In the preprocessing phase, we use a new spanned sub-meshes simplification technique to build view-dependence trees I/O-efficiently, which preserves the correct edge collapsing order and thus assures the run-time(More)
Research on dynamic algorithms for geometric problems has received increasing attention in the last years, and is motivated by many important applications in circuit layout, computer graphics, and computer-aided design. In this paper we survey dynamic algorithms and data structures in the area of computational geometry. Our work has a twofold purpose: it(More)
Contour trees are used when high-dimensional data are preprocessed for efficient extraction of isocontours for the purpose of visualization. So far, efficient algorithms for contour trees are based on processing the data in sorted order. We present a new algorithm that avoids sorting of the whole dataset, but sorts only a subset of so-called(More)
In this paper, we present a novel out-of-core 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 two-level indexing scheme. First, by our meta-cell technique,(More)
In this paper we give I/O-optimal 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(More)
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(More)
We present an extensive experimental study comparing the performance of four algorithms for the following orthogonal segment intersection problem: given a set of horizontal and vertical line segments in the plane, report all intersecting horizontal-vertical pairs. The problem has important applications in VLSI layout and graphics, which are large-scale in(More)
2, 6, 8, 14, 15, 21, 25, 26, 291. We describe a new technique for dynamically maintaining the trapezoidal decomposition of a connected planar map M with 7~ vertices, and apply it to the development of a unified dynamic data structure that supports point-location, ray-shooting, and shortest-path queries in M. The space requirement is O(nlog n).(More)