A Method for Solving the Visibility Problem

Hornung, Christoph

doi:10.1109/mcg.1984.275874

Cited by 14 publications

(5 citation statements)

References 8 publications

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“…We continuously monitor the mesh for selfintersection and assign appropriate depth values to the overlapping parts. This process is similar to the hidden-line removal algorithm in [Hornung 1984]. We first locate boundary intersections and then search for overlapping regions starting from those boundary intersections.…”

Section: Collision Detection and Depth Adjustmentmentioning

confidence: 99%

As-rigid-as-possible shape manipulation

2005

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We present an interactive system that lets a user move and deform a two-dimensional shape without manually establishing a skeleton or freeform deformation (FFD) domain beforehand. The shape is represented by a triangle mesh and the user moves several vertices of the mesh as constrained handles. The system then computes the positions of the remaining free vertices by minimizing the distortion of each triangle. While physically based simulation or iterative refinement can also be used for this purpose, they tend to be slow. We present a two-step closed-form algorithm that achieves real-time interaction. The first step finds an appropriate rotation for each triangle and the second step adjusts its scale. The key idea is to use quadratic error metrics so that each minimization problem becomes a system of linear equations. After solving the simultaneous equations at the beginning of interaction, we can quickly find the positions of free vertices during interactive manipulation. Our approach successfully conveys a sense of rigidity of the shape, which is difficult in space-warp approaches. With a multiple-point input device, even beginners can easily move, rotate, and deform shapes at will.

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Section: Collision Detection and Depth Adjustmentmentioning

confidence: 99%

As-rigid-as-possible shape manipulation

2005

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“…For each of the subdivided curves, only one point in its open interval needs to be tested for its invisibility count. As noted in [2,11], silhouette curves can overlap; that is, a silhouette curve can be G 1 continuous and still have cusps in its projection (called a curtain fold [2]). Since the visibility of the silhouette curves may change at curtain folds, they must be split at these points.…”

Section: C I C C For Each C I All Points P E C I Have the Same Imentioning

confidence: 99%

“…The algorithm presented here has several stages (including extracting curves of interest, splitting at critical points, and visibility testing). Surface coherence is used extensively to reduce the number of ray tests one needs to perform to detect curve visibility, in a similar way to that for polygons [10,11].…”

Section: Introductionmentioning

confidence: 99%

Hidden curve removal for free form surfaces

ElberGershon

CohenElaine

1990

SIGGRAPH Comput. Graph.

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This paper describes a hidden curve algorithm specifically designed for sculptured surfaces. A technique is described to extract the visible curves for a given scene without the need to approximate the surface by polygons. This algorithm produces higher quality results than polygon based algorithms, as most of the output set has an exact representation. Surface coherence is used to speed up the process. Although designed for sculptured surfaces, this algorithm is also suitable for polygonal data.

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“…In particular, hidden line and surface removal algorithms in computer graphics are related to visibility computations [FDHF90,Hor84,SSS74,HG77]. Similarly, accessibility computations in manufacturing applications are based on Gauss maps and visibility sets [Woo94,CCW93,GWT94].…”

Section: Introductionmentioning

confidence: 99%