N. Chin and S. Feiner. Fast object-precision shadow generation for areal light sources using BSP trees. Comput. Graph. 25:21--30, 1992.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....n. Binary space partitions were introduced in the graphics community [8, 13] to solve hidden surface removal problems, and since then have been used for a wide variety of applications, including solid modeling, ray tracing, shadow generation, and robotics, to name only a representative sample [1, 4, 5, 9, 10, 14]. Because # Subhash Suri s research on this paper was partially supported by National Science Foundation grants CCR 9901958 and ANI 9813723. most computer graphics is concerned with visualizing 3 space, is the most important setting for BSPs. Computational geometers have studied BSPs since ....

N. Chin and S. Feiner. Fast object-precision shadow generation for areal light sources using BSP trees. Comput. Graph., 25:21--30, March 1992.

....the number of leaf cells. Fuchs et al. 14] introduced BSP trees, following earlier work by Schumacker et al. 37] as a tool for computing depth orders for rendering. Since their introduction, BSP trees have been used for many other applications in computer graphics, including shadow generation [8, 9], solid modeling [26, 41] geometric data repair [25] and visibility culling for interactive walkthroughs [39] As in the case for intersection detection, the worstcase complexity bounds for BSPs of polyhedra in IR are quite pessimistic. Chazelle s polyhedron, described in the previous ....

N. Chin and S. Feiner. Fast object-precision shadow generation for areal light sources using BSP trees. Comput. Graph. 25:21--30, Mar. 1992.

....graphics hardware; they are emulated in software and, therefore, slow down rendering performance significantly. Apart from the latter accumulation method, few shadow volume algorithms address soft shadow generation for interactive rendering. One exception is Chin and Feiner s Area SVBSP tree [Chi92] that, for static polygonal environments, stores penumbra and umbra regions in a pair of BSP trees. Most other algorithms for soft shadows are based on variants of Williams depth map algorithm. We first cover algorithms to reduce aliasing effects by softening the shadow boundary. To do so, ....

Chin, N., and Feiner, S. Fast object-precision shadow generation for area light sources using BSP trees. Computer Graphics (Symposium on Interactive 3D Graphics), 25:21-30, 1992.

....it grows bigger it also grows further away from the viewcell. For this reason we periodically dump some of the intermediate virtual occluders into the dense set. This aggregate umbra algorithm bears some conceptual similarity to algorithms that compute shadow volumes from an area light source [4, 5], or even to discontinuity meshing methods [9, 15] However, here we have two important advantages. First, the aggregate umbra does not necessarily have to be accurate, but conservative, and can thus be calculated significantly faster than area shadow algorithms. The other advantage lies in the ....

N. Chin and S. Feiner. Fast object-precision shadow generation for area light sources using BSP trees. In ACM Computer Graphics (Symp. on Interactive 3D Graphics), pages 21--30, 1992.

....of shadow boundaries. They suffer however from robustness problems and computational expense, both in the preprocess and for rendering since they are very polygon fill intensive [17] Various other methods have been developed, for example the methods of Campbell and Fussell [3] or Chin and Feiner [4] based on BSP trees, which also run into robustness or memory problems due to the geometric operations and data structures involved. Discontinuity meshing approaches were introduced by Heckbert [13] and Lischinski et al. 16] These methods compute shadow discontinuity surfaces (line swaths) by ....

N. Chin and S. Feiner. Fast object-precision shadow generation for areal light sources using BSP trees. In Computer Graphics (1992.

.... The Binary Space Partition (BSP, also known as BSP tree) originally proposed by Schumacker et al. 26] and further refined by Fuchs et al. 16] is a hierarchical partitioning of space widely used in several areas, including computer graphics (global illumination [7] shadow generation [10, 11], visibility determination [4, 28] and ray tracing [21] solid modeling [22, 20, 29] geometric data repair [19] robotics [5] network design [18] and surface simplification [3] Key to Support was provided by National Science Foundation research grant CCR 93 01259, by Army Research Office ....

N. Chin and S. Feiner, Fast object-precision shadow generation for areal light sources using BSP trees, Comput. Graph. (Proc.

....3.1. First Algorithm (COCL Algorithm) In rendering shadows of an object, the shape and size of its umbral and penumbral regions vary according to the shape and size and position of a given light source and the object. Usually, a complicated algorithm is required to render general penumbrae[6, 7, 5, 3, 8, 11]. However, if the light source and the object are located at particular positions and both have particular shapes, a simple algorithm is sufficient to compute the geometry of umbral and penumbral regions. For example, if an object is a flat circular saucer and placed horizontally to a projection ....

N. Chin and S. Feiner. Fast object-precision shadow generation for area light sources using BSP trees. In Computer Graphics (Proc. of the

....shadow. The first to explicitly take in account extremal boundaries were Nishita and Nakamae [19] by using shadow volumes and considering all pairs of objects in the scene. More efficient methods based on Shadow Volume BSP trees were later presented by Campbell and Fussell [3] and Chin and Feiner [4]. Campbell and Fussell [3] noted that the illumination function has maxima, minima and discontinuities within the penumbra regions and they used sampling to locate these. The discontinuities occur along curves in the penumbra where the visible part of the source changes qualitatively [11] These ....

....always possible. This is because an area cannot necessarily be unambiguously classified against the root plane at each node. Previous researchers dealing with area light sources realized this problem but being unable to find a satisfactory solution, their methods resulted in unnecessary processing [3, 4, 10]. First we build a normal BSP tree (T 0 ) using the scene polygons that have the source totally in front of them and then we add any polygons that cut the source with their plane (we call the latter offending) Polygons that have the source totally behind are irrelevant to the shadow algorithm, ....

N. Chin and S. Feiner. Fast object-precision shadow generation for area light sources using BSP trees. In ACM Computer Graphics (Symp. on Interactive 3D Graphics), pages 21--30, 1992.

....can jointly hide a point from the light source when neither polygon alone hides the point. Due to such difficulty, there are some approximated solutions to find the umbra shadow volume of two or more polygons. These simply merge the primitive umbra shadow volumes made by each individual polygon [11 12]. These methods however fail to identify the invisible polygons jointly occluded by multiple polygons. Teller developed a method to exactly calculate antipenumbra, which is conceptually equivalent to umbra, through a sequence of n portals or n convex areal holes in O(n 2 ) This method is ....

N.Chin and S. Feiner, Fast Object-precision Shadow Generation for Area Light Source using BSP Trees, In ACM Symposium on Interactive 3D Graphics, pages 21-30, 1992.

....and or a fee. SCG 01, June 3 5, 2001, Medford, Massachusetts, USA. Copyright 2001 ACM 1 58113 357 X 01 0006 . 5.00. called painter s algorithm [13] Since then they have been used extensively, not only in computer graphics but also in other elds. Example applications are shadow generation [9, 10], set operations on polyhedra [19, 24] geometric data repair [16] visibility preprocessing for interactive walkthroughs [23] and cell decomposition methods in motion planning [4] In all these applications it is important to keep the size of the BSP, that is the number of fragments generated, ....

N. Chin and S. Feiner. Fast object-precision shadow generation for areal light sources using BSP trees. Comput. Graph., 25:21-30, March

....applications. However, it is not suitable for interactive modification of objects in the scene, since any change in an object s position could destroy the ordering and may require the reconstruction of the shadow tree. Similar structures were used in [10] for image representation and in [4, 2] for determining illumination discontinuities from area light sources. The algorithm presented here employs a generalization of the SVBSP tree that does not require the construction of a BSP tree of the original scene polygons, and that does support near real time incremental changes to the SVBSP ....

....The algorithm only produces shadow umbras, which although better than no shadows at all, still leaves a lot to be desired in terms of realism. Future work involves extending the algorithm to soft shadows, produced by area light sources. This was considered, for static scenes, by Chin and Feiner in [4]. ACKNOWLEDGMENTS Y. Chrysanthou s work is supported by the Keddy Fletcher Warr Studentship (University of London) and the Overseas Research Students Fee Support Scheme. ....

N. Chin and S. Feiner. Fast object-precision shadow generation for area light sources using BSP trees. In ACM Computer Graphics (Symp. on Interactive 3D Graphics), pages 21--30, 1992.

....extension would be to include more types of discontinuity edges in out algorithm. For instance, we could compute soft shadow edges, refracted edges, and edges reflected on curved surfaces. To handle soft shadows we could use an extension of the shadow volume algorithm to area light sources [3]. We could use our method to compute ray traced walkthroughs, exploiting frame coherence for reusing samples between successive frames. Determining which samples could be reused would depend on the movement of the viewer and the materials of the scene. We believe that our method could be very ....

Norman Chin and Steven Feiner. Fast object-precision shadow generation for area light sources using bsp trees. In Proceedings of 1992 Symposium on Interactive 3D Graphics (Cambridge, Massachusetts, March 29--April 1, 1992), March 1992.

....sources [1] or by point sampling the source itself [4, 15] This is prone to aliasing if an insufficient number of samples is used. Images of a higher quality can be achieved using algorithms that use shadow volumes and or discontinuity meshing to determine the exact vis ibility of a source [11, 10, 2, 3, 7, 5, 14, 6]. Such techniques are very expensive and have only been designed to compute exact visibility for polygonal environments. Finally, shadow maps have also been used to approximate soft shadows, most recently by convolving source and occluder images to produce a soft shadow texture[12, 13] Such ....

Chin, N., Feiner, S., "Fast Object-Precision Shadow Generation for Area Light Sources Using BSP Trees", ACM Computer Graphics (SIGGRAPH Symp. on Inter. 3D Graphics 1992).

....point light sources [1] or by point sampling the source itself [4, 15] This approach is subject to aliasing if too few samples are used. Images of a higher quality can be achieved using algorithms that use shadow volumes and or discontinuity meshing to determine the exact visibility of a source [2, 3, 5, 7, 9, 14]. These techniques are very expensive and have only been designed to compute exact visibility for polygonal environments. Finally, shadow maps have also been used to texture map soft shadows, either by pre calculating an approximation using multiple light source samples and combining them in an ....

Chin, N., Feiner, S., "Fast Object-Precision Shadow Generation for Area Light Sources Using BSP Trees", ACM Computer Graphics (SIGGRAPH Symp. on Inter. 3D Graphics 1992).

....similar problems, namely the inadequate memory and preprocessing complexities. Further problems belonging to the VFR class include algorithms used to determine soft shadows due to areal light sources. Continuous algorithms for real time soft shadow generation were studied by Chin and Feiner [33], Loscos and Drettakis [112] and Chrysanthou [34, 35, 39] Discrete solutions have been proposed by Nishita [129] Brotman and Badler [21] and Soler and Sillion [167] An exact algorithm computing antipenumbrae of an areal light source was introduced by Teller [190] In the scope of radiosity ....

N. Chin and S. Feiner. Fast object-precision shadow generation for areal light sources using BSP trees. In D. Zeltzer, editor, Computer Graphics (1992 Symposium on Interactive 3D Graphics), volume 25, pages 21--30, Mar. 1992.

....them into the following three categories: exact, point sampled and conservative visibility computations and focus the discussion on volume visibility approaches. Examples of exact visibility representations are the aspect graph [20] or the visibility skeleton [9] and exact shadow boundaries [3, 8, 23, 27]. As mentioned above, they are impractical for complex scenes. Point sampling algorithms calculate visibility up to the accuracy of the display resolution [5, 7, 13] One sample ray is sent into the scene and the obtained visible surface is reused over an area (e.g. a pixel or solid angle on the ....

Chin, Norman and Steven Feiner, "Fast Object-Precision Shadow Generation for Area Light Sources Using BSP Trees," Symposium on Interactive Graphics (1992), pp 21-30.

.... The Binary Space Partition (BSP, also known as BSP tree) originally proposed by Schumacker et al. 31] and further re ned by Fuchs et al. 18] is a hierarchical partitioning of space widely used in several areas, including computer graphics (global illumination [9] shadow generation [12, 13], visibility determination [4, 33] and ray tracing [24] solid modeling [27, 25, 34] geometric data repair [23] robotics [5] network design [21] and surface simpli cation [3] Key to the BSP s success is that it serves both as a model for an object (or a set of objects) and as a data ....

N. Chin and S. Feiner, Fast object-precision shadow generation for areal light sources using BSP trees, Proc. 1992 Sympos. Interactive 3D Graphics, 1992, pp. 21-30.

.... in real time, so filtering a small superset of objects visible from a given viewpoint is a critical step in obtaining fast rendering algorithms [23] Besides these two important applications, BSPs have been used for many other problems in graphics (including ray tracing [16] and shadow generation [7, 8]) solid modeling [15, 24] geometric data repair [14] robotics [4] etc. A BSP B for a set S of objects in IR d is a binary tree, each of whose nodes v is associated with an open convex polytope Delta v , called the cell of v, and the set S v = fs Delta v j s 2 Sg of objects clipped to ....

N. Chin and S. Feiner. Fast object-precision shadow generation for areal light sources using BSP trees. Comput. Graph. 25:21--30, Mar. 1992. Proc. 1992 Sympos. Interactive 3D Graphics.

....By fragmenting the triangles, the BSP ensures that a back to front order from any viewpoint can be determined for the fragments. BSPs have subsequently proven to be versatile, with applications in many problems apart from hiddensurface removal [8, 101] global illumination [23] shadow generation [29, 30], solid modelling [75, 78, 102] ray tracing [74] robotics [12] and approximation algorithms for network design [66] and surface simplification [7] The efficiency of our model repair and hidden surface removal algorithms algorithms as well as the applications mentioned above inherently depends ....

....an underlying data structure, their running time inherently depends on properties of the BSP such as size and height. In fact, the same is true of algorithms that use the BSP in a variety of different applications: hidden surface removal itself [8, 101] global illumination [23] shadow generation [29, 30], solid modelling [75, 78, 102] ray tracing [74] robotics [12] and approximation algorithms for network design [66] and surface simplification [7] As a result, there has been a lot of effort to construct BSPs of small size. While several simple heuristics have been developed for constructing ....

N. Chin and S. Feiner, Fast object-precision shadow generation for areal light sources using BSP trees, Proc. 1992 Sympos. Interactive 3D Graphics, 1992, pp. 21--30.

....[5] The algorithm extended the approach of [6] to directly compute umbra and penumbra boundaries from area sources, drawing on techniques from the shadow algorithm of [30] Since this paper is derived from Campbell s dissertation, details will be provided later in the paper. Chin and Feiner [8] also use umbra and penumbra shadow boundaries to refine a mesh, and they also compute source visibility analytically. A detailed comparison of their method to the one being presented here will take place in Section . source blocker e v critical surface critical curve Figure 1: A VE event. The ....

....in a progressive refinement [9] framework. Mesh elements associated with illuminated surfaces are subdivided along shadow boundaries. The resultant elements are then categorized into three visibility classifications: fully lit (LIT) partially lit (PENUMBRA) and shadowed (UMBRA) as in [30] and [8]. This is shown in Figure 4. LIT and PENUMBRA elements are then examined for potential further subdivision; such elements exhibiting a variation of more than I ffl are subdivided accordingly. Intensities are then computed for each mesh vertex. The resultant mesh may be rendered after any or all ....

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Norman Chin and Steven Feiner. Fast object-precision shadow generation for area light sources using bsp trees. In 1992 Symposium on Interactive 3D Graphics, Cambridge, MA, March 1992.

....speed. Scanline shadow algorithms[App68, BK70] requires significant pre processing and are thus not suitable for moving objects and lights. Polygon subdivision[AWG78, NN85] shadow volume algorithms [Cro77, BB84, TN85, Ber86, Max86, FGH 85, Hei91] and the BSP tree shadow volume method[CF89, CF92] are restricted to polygonal models and inefficient for scenes with a large number of polygons. Polygon subdivision algorithms algorithm is also difficult to implement robustly. For a survey of some of the algorithms see [WPF90] Ray tracing [Whi79, Kay79] and radiosity algorithms [GTGB84, CG85] ....

Norman Chin and Steven Feiner. Fast object-precision shadow generation for areal light sources using BSP trees. In Computer Graphics (1992 Symposium on Interactive 3D Graphics), volume 25, pages 21-- 30, March 1992.

....can then be used to control adaptive subdivision of the light source or occluders. Another recent algorithm approximates umbra volumes by constructing penumbra trees and umbra trees ; these are BSP trees [8] whose polyhedral leaf cells bound polygon fragments in partial or complete shadow [5]. For polygonal light sources, holes, and occluders, the boundary between total illumination (antiumbra) and partial illumination (penumbra, antipenumbra) is piecewise planar. The boundary between partial illumination (penumbra, antipenumbra) and no illumination (umbra) however, generally ....

Norman Chin and Steven Feiner. Fast object-precision shadow generation for area light sources using BSP trees. In Proc. 1992 Symposium on Interactive 3D Graphics, pages 21--30, 1992.

....for an arbitrary set of objects. By fragmenting the objects, the BSP ensures that a back to front order from any viewpoint can be determined for the fragments. BSPs have subsequently proven to be versatile, with applications in many other problems global illumination [6] shadow generation [10, 11], visibility problems [4, 30] solid modeling [23, 25, 31] geometric data repair [20] ray tracing [22] robotics [5] and approximation algorithms for network design [19] and surface simplification [3] Algorithms have also been developed to construct BSPs for moving objects [1, 12, 24, 32] ....

N. Chin and S. Feiner, Fast object-precision shadow generation for areal light sources using BSP trees, Comput. Graph. (Proc. 1992 Symp. on Interactive 3D Graphics), Vol. 25, 1992, pp. 21--30.

....Reclassification of child interactions after subdivision. The linespace algorithms guarantee conservative visibility, in that blockers are only discarded from interactions if they are definitely known to be disjoint. Existing algorithms use point sampling [2, 6, 11, 16] or point to area visibility [3, 4] techniques and therefore do not guarantee correct inter area visibility determination. In contrast, we establish exact visibility information where possible, and adaptively subdivide until the uncertainty of visibility estimation in the remaining cases is so small as to be unimportant. The ....

Chin, N., and Feiner, S. Fast Object-Precision Shadow Generation for Area Light Sources Using BSP Trees. In Proc. 1992 Symposium on Interactive 3D Graphics (1992), pp. 21\Gamma30.

....and incorporating these boundaries in the partition of the scene. This is not sufficient since a penumbra region will usually contain discontinuities that require further subdivision of the region. Chin and Feiner compute the umbral and penumral boundaries for point and area light sources [CF89, CF92] using binary space partitioning trees. Campbell and Fussell [CF91] Lischinski, Tampieri, and Greenberg [LTG92] and others compute a subset of the shadow boundaries which includes the boundaries of the umbra and penumbra regions. The most complete algorithm to date is that of Heckbert [Hec92] ....

Norman Chin and Steven Feiner. Fast objectprecision shadow generation for area light sources using bsp trees. 1992 Symposium on Interactive 3D Graphics, pages 21--30, March 1992.

....binary space partition (BSP) 13, 23] is a data structure that fragments the objects and ensures that a back to front order from any viewpoint can be determined for the fragments. BSPs have proven to be versatile, with applications in many other problems global illumination [5] shadow generation [7, 8, 9], visibility problems [3, 25] solid geometry [19, 20, 26] geometric data repair [16] ray tracing [18] robotics [4] and approximation algorithms for network design [15] and surface simpli cation [2] Informally, a BSP B for a set of polygons in R 3 is a binary tree. Each node v of B is ....

N. Chin and S. Feiner, Fast object-precision shadow generation for areal light sources using BSP trees, Computer Graphics (1992 Symp. on Interactive 3D Graphics) Vol. 25, 1992, pp. 2130.

....of v. The efficiency of the traversal, and thus of the hidden surface removal algorithm, depends upon the size of the BSP. The BSP has subsequently proven to be a versatile data structure with applications in many other problems that arise in practice global illumination [5] shadow generation [7, 8, 9], ray tracing [19] visibility problems [3, 23] solid geometry [17, 18, 24] robotics [4] and approximation algorithms for network flows and surface simplification [2, 16] Although several simple heuristics have been developed for constructing BSPs of reasonable sizes [3, 13, 14, 23, 24] ....

N. Chin and S. Feiner. Fast object-precision shadow generation for areal light sources using BSP trees. In D. Zeltzer, editor, Computer Graphics (1992 Symposium on Interactive 3D Graphics), volume 25, pages 21--30, Mar. 1992.

....the shadow. The first to compute the exact extremal boundaries were Nishita and Nakamae [18] by using shadow volumes and considering all pairs of objects in the scene. More efficient methods based on Shadow Volume BSP trees were latter presented by Campbell and Fussell [3] and Chin and Feiner [4]. As correctly noted by Campbell and Fussell [3] the illumination function has maxima, minima and discontinuities within the penumbra regions. They used sampling to locate them. These discontinuities occur along curves in the penumbra where the visible part of the source changes qualitatively ....

N. Chin and S. Feiner. Fast object-precision shadow generation for area light sources using BSP trees. In ACM Computer Graphics (Symp. on Interactive 3D Graphics), pages 21--30, 1992.

.... The Binary Space Partition (BSP, also known as BSP tree) originally proposed by Schumacker et al. 26] and further refined by Fuchs et al. 16] is a hierarchical partitioning of space widely used in several areas, including computer graphics (global illumination [7] shadow generation [10, 11], visibility determination [4, 28] and ray tracing [21] solid modeling [22, 20, 29] geometric data repair [19] robotics [5] network design [18] and surface simplification [3] Key to Support was provided by National Science Foundation research grant CCR 93 01259, by Army Research ....

N. Chin and S. Feiner, Fast object-precision shadow generation for areal light sources using BSP trees, Comput. Graph. (Proc. 1992 Symp. on Interactive 3D Graphics), Vol. 25, 1992, pp. 21--30.

....78] or binary space partitioning (BSP) trees [Chin Feiner90] Nishita went further, computing penumbra boundaries from area light sources [Nishita Nakamae83] thereby producing some amazingly realistic pictures without simulating interreflection. Chin has recently done the same using BSP trees [Chin Feiner92] 1.2 Motivation Current radiosity algorithms work well for some scenes: the progressive radiosity algorithm [Cohen et al. 88] is relatively fast and its artifacts are often imperceptible. Sometimes, however, existing algorithms are very slow, they exhibit objectionable artifacts, and they are ....

....they can pay off because they allow a 12 Discontinuity Meshing for Radiosity much coarser mesh to be used. The approach followed here allows very accurate solutions to be explored. Alternative approaches using progressive radiosity and BSP trees appear to be easier to implement [Campbell91,Chin Feiner92] but the accuracy of their results has not yet been demonstrated. Although there are many discontinuities in most scenes, most of them are insignificant, so it is likely that discontinuity meshing can be practical for complex scenes. Experiments are needed to discover good measures of ....

Norman Chin and Steven Feiner. Fast object-precision shadow generation for area light sources using BSP trees. In 1992 Symp. on Interactive 3D Graphics, Mar. 1992.

....an arbitrary set of objects. By fragmenting the objects, the BSP ensures that a back to front order from any viewpoint can be determined for the fragments [17] The BSPs has subsequently proven to be versatile, with applications in many other problems global illumination [7] shadow generation [11, 12], visibility problems [5, 29] solid modeling [22, 24, 30] geometric data repair [19] ray tracing [21] robotics [6] and approximation algorithms for network design [18] and surface simplification [4] Algorithms have also been developed to construct BSPs for moving objects [2, 13, 23, 31] ....

N. Chin and S. Feiner, Fast object-precision shadow generation for areal light sources using BSP trees, Proc. 1992 Symp. on Interactive 3D Graphics, 1992, pp. 21--30.

....radiosity mesh generation. With this approach, surfaces are subdivided into fully lit, penumbra, and umbra regions by splitting along lines or curves where visibility changes. In Chin and Feiner s soft shadow method, polygons are split using BSP trees, and these sub polygons are then pre shaded [6]. They achieved rendering times of under a minute for simple scenes. Drettakis and Fiume used more sophisticated computational geometry techniques to precompute their subdivision, and reported rendering times of several seconds [9] Most radiosity methods discretize each surface into a mesh of ....

Norman Chin and Steven Feiner. Fast object-precision shadow generation for area light sources using BSP trees. In 1992 Symp. on Interactive 3D Graphics, pages 21--30. ACM SIGGRAPH, Mar. 1992.

....to solutions which are both numerically and visually more accurate. Another advantage is that higher order elements can be used much more effectively in conjunction with discontinuity meshes [16] Several algorithms have been described that use the idea of discontinuity meshing to various extents [1, 3, 6, 15]. Recently, a progressive radiosity DM algorithm was described by the authors [18] The meshing in this algorithm is automatic. Using analytical visibility and form factor computations followed by quadratic interpolation it has produced radiosity solutions of impressive visual accuracy. This ....

Chin, Norman and Steven Feiner. "Fast Object-Precision Shadow Generation for Area Light Sources Using BSP Trees," in Proceedings of 1992 Symposium on Interactive 3D Graphics, March 1992.

.... The Binary Space Partition (BSP) is a hierarchical partitioning of space that was originally proposed by Schumacker et al. 19] and was further refined by Fuchs et al. 10] The BSP has been widely used in several areas, including computer graphics (global illumination [4] shadow generation [6, 7], visibility determination [3, 21] and ray tracing [15] solid modeling [16, 22] geometric data repair [12] network design [11] and surface simplification [2] The BSP has A preliminary version of this paper appeared as a communication in the Proceedings of the 13th Annual ACM Symposium ....

N. Chin and S. Feiner, Fast object-precision shadow generation for areal light sources using BSP trees, Proc. 1992 Sympos. Interactive 3D Graphics, 1992, pp. 21-- 30.

....volumes. Campbell refined his initial approach given by [CF90] into a more analytical approach in [Cam91] which modelled the umbral and penumbral volumes. The original work by Chin and Feiner [CF89] involving shadow volume BSP trees (SVBSP trees) was also extended to handle area light sources in [CF92], making it one of the most rapid methods. However, such techniques can not be used interactively, as they require a full re computation of the various shadows for each frame of an animation. The most recent developments into shadow determination and representation in objectspace have been made in ....

Norman Chin and Steven Feiner. Fast Object-Precision Shadow Generation for Area Light Sources Using BSP Trees. In ACM Computer Graphics (Symp. on Interactive 3D Graphics), pages 21--30, 1992.

.... in real time, so filtering a small superset of objects visible from a given viewpoint is a critical step in obtaining fast rendering algorithms [23] Besides these two important applications, BSPs have been used for many other problems in graphics (including ray tracing [16] and shadow generation [7, 8]) solid modeling [15, 24] geometric data repair [14] robotics [4] etc. A BSP B for a set S of objects in IR d is a binary tree, each of whose nodes v is associated with an open convex polytope Delta v , called the cell of v, and the set S v = fs Delta v j s 2 Sg of objects clipped to ....

N. Chin and S. Feiner. Fast object-precision shadow generation for areal light sources using BSP trees. Comput. Graph. 25:21--30, Mar. 1992. Proc. 1992 Sympos. Interactive 3D Graphics.

.... [2] first computed shadow boundaries for complex environments using BSP trees from point light sources, and then extended the method to compute the extremal boundaries for area sources in [3] Chin and Feiner [4] performed a similar computation, and also presented an extension to area sources in [5]. Additional lines of the mesh, interior to the penumbrae, were computed in [22] again using BSP trees, and in [19] using a two dimensional visibility algorithm. In all these approaches, computing the exact visible portion of the source at a given point involves a visibility computation requiring ....

Norman Chin and Steven Feiner. Fast object-precision shadow generation for areal light sources using BSP trees. In David Zeltzer, editor, Computer Graphics (1992 Symposium on Interactive 3D Graphics), volume 25, pages 21--30, March 1992.

No context found.

N. Chin and S. Feiner. Fast object-precision shadow generation for areal light sources using BSP trees. Comput. Graph. 25:21--30, 1992.

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