Roth, S., "Ray casting for modeling solids," Comp. Graph. Im. Proc., 18, pp. 109--144, 1982.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....require pre processing the 22 silhouette cones. In fact, there is no explicit data structure used to represent the silhouette volumes other than the reference images. Using ray tracing, one can render an object defined by a tree of CSG operations without explicitly computing the resulting solid [25]. This is done by considering each ray independently and computing the interval along the ray occupied by each object. The CSG operations can then be applied in 1D over the sets of intervals. This approach requires computing a 3D ray solid intersection. In this system, the solids in question are a ....

Roth, S. D. "Ray Casting for Modeling Solids." Computer Graphics and Image Processing, 18 (February 1982), 109-144.

....unique views of the visual hull directly from the silhouette images, without constructing an intermediate volumetric or polyhedral model. This is accomplished by merging the cone intersection calculation with the rendering process, resulting in an algorithm similar in spirit to CSG ray casting [15]. However, sometimes an explicit three dimensional model of the visual hull is desired. There has been work [4, 14] on general Boolean operations on 3D polyhedra. Most of these algorithms require decomposing the input polyhedra into convex polyhedra. Then, the operations are carried out on the ....

Roth, S. D., "Ray Casting for Modeling Solids," Computer Graphics and Image Processing, 18 (Feb 1982), pp. 109-144.

....and Phrases: Ray Tracing, Anti Aliasing Introduction Ray tracing is a very powerful yet simple approach to image synthesis. Though expensive computationally, it has generated some of the most realistic scenes to date [10, 13, 17] It is also used for entertainment and computer aided design [9, 15]. However, apart from the computationally expensive method of supersampling, no general method exists to remove artifacts created by aliasing. Furthermore, at present, there is no general procedure to decide what level of detail is sufficient in a texture map or in a procedural or hierarchical ....

Roth, S.D., "Ray Casting for Modeling Solids", Computer Graphics and Image Processing, Vol. 18, 1982, pp. 109-144.

....ray with primitives in the leaves of a CSG tree are collected in a list. Finally the Boolean combinations can be done directly with intersection intervals of the ray. The threedimensional problem of combining volumes is thereby reduced to the one dimensional problem of combining intervals of a ray [ROTH82]. An alternative data structure for the representation of CSG expressions is a directed acyclic graph (DAG) where primitive objects are stored only once, a feature that was called object instancing in 4 [RUBI80] This implies that transformations are stored as internal nodes of a CSG DAG, which ....

Roth S.D (1982) Ray Casting for Modeling Solids. Computer Graphics and Image Processing, Vol. 18, pp. 109-144

....[11, 15] or Bezier patches [10] Constructive solid geometry. Objects defined implicitly by formulas of constructive solid geometry also seem easy to incorporate into the ZZbu #er algorithm. In the rendering phase, such objects would be handled in exactly the same way as for ordinary ray tracing [2, 26]. The novelty comes in scan conversion, where it is necessary to estimate the opaque flag of the union, intersection, and di#erence of primitives. 7 Conclusion The ZZ bu#er algorithm produces images of exceptional quality. It can render simple scenes fast, and render complex scenes at a speed ....

Roth, S. D., "Ray Casting for Modeling Solids," Computer Graphics and Image Processing vol. 18 (1982), 109--144.

....not require preprocessing the silhouette cones. In fact, there is no explicit data structure used to represent the silhouette volumes other than the reference images. Using ray tracing, one can render an object defined by a tree of CSG operations without explicitly computing the resulting solid [25]. This is done by considering each ray independently and computing the interval along the ray occupied by each object. The CSG operations can then be applied in 1D over the sets of intervals. This approach requires computing a 3D ray solid intersection. In our system, the solids in question are a ....

....representation. In fact, our IBVH representation is equivalent to computing exact 3D silhouette cone intersections and rendering the result with traditional rendering methods. Our technique for computing the visual hull is analogous to finding CSG intersections using a ray casting approach [25]. Given a desired view, we compute each viewing ray s intersection with the visual hull. Since computing a visual hull involves only intersection operations, we can perform the CSG calculations in any order. Furthermore, in the visual hull context, every CSG primitive is a generalized cone (a ....

Roth, S. D. "Ray Casting for Modeling Solids." Computer Graphics and Image Processing, 18 (February 1982), 109-144.

....by the network arbitrator. 34 2. 6 Computer Simulation Based on the proposed neural network model, we have developed and implemented a computer simulation program called OPEN (Object identification and Pose Estimation Network simulator) The objects are generated using ray casting algorithm [40]. In this section, we are going to describe the 3 D scene generator and the OPEN simulation program. 2.6.1 Object Generation using Ray CastingAlgorithm Roth [40] models solid objects by combining primitive solids, such as blocks and cylinders, using the set operators union, intersection, and ....

....program called OPEN (Object identification and Pose Estimation Network simulator) The objects are generated using ray casting algorithm [40] In this section, we are going to describe the 3 D scene generator and the OPEN simulation program. 2.6. 1 Object Generation using Ray CastingAlgorithm Roth [40] models solid objects by combining primitive solids, such as blocks and cylinders, using the set operators union, intersection, and difference. We have implemented his model in ANSI C and the implemented program can be easily ported to various platforms (e.g. VAX, SUN, and PCs) The program ....

S. D. Roth, "Ray Casting for Modeling Solids," Computer Graphics and Image Processing, 18, pp. 109-144, 1982.

....methods require considerable amounts of computation [Requicha85] and are too slow for interactive modification of the model. Several well known graphics algorithms have been customized for CSG display. This includes scanline methods [Atherton83, Bronsvoort87] ray tracing and ray casting [Roth82], image subdivision [Cameron94] octrees [Meagher84] and even point sampling and voxel reconstruction [Breen91] Again, all of these methods do not provide interactive performance. Binary Space Partitioning (BSP) trees, known in computer graphics for acceleration of many types of computations, ....

Roth, S.D., Ray casting for modeling solids. CVGIP, 18(2):109-- 144, 1982.

.... and transmission [1,4] To visualize composite objects, the ray tracing technique uses Constructive Solid Geometry (CSG) methods, in which it is possible to ray trace objects formed by elementary set Operations, such as union, intersection and set difference (called CSG objects from now on) [5]. Using this as a starting point, we establish a mapping between 3D Minkowski objects and objects defined in terms of CSG Operations, which can subsequently be visualized by the standard ray tracing technique. In particular, we use a basic set of elementary shapes, and derive a decomposition of a ....

Roth, S., "Ray casting for modeling solids," Comp. Graph. Im. Proc., 18, pp. 109--144, 1982.

....polygonal objects (Fuchs[17] The implicit ordering given by a BSP tree is convenient for those applications that require a processing of the polygons in sorted order, e.g. displaying with hidden surface removal. CSG (Constructive Solid Geometry) defines an object through a binary tree (Roth[50]) A CSG tree usually contains an efficient bounding volume hierarchy (hierarchical coherence) There are a large number of other data structures described in literature that make use of coherence. In computational geometry many data structures utilize subdivisions to reduce the manipulation cost ....

....Examples are interval trees, segment trees, range trees, etc. The following references deal with data structures that exploit coherence properties: Arvo[2] Ballard[4] Blinn[7] Foley[16] Fuchs[17] Fujimoto[18] Glassner[20,21,22] Gr ller[25] Kajiya[34] Pearce[44] Preparata[46] Roth[50], Weghorst[60] Wyvill[62] Other Another strategy for exploiting coherence is to handle coherent sets of objects together instead of processing single objects by themselves. Bounding volume hierarchies do follow this principle for objects with a given hierarchical ordering. One example in the ....

Roth, S.D., "Ray Casting for Modeling Solids", Computer Graphics and Image Processing, Vol. 18, 1982, pp. 109-144.

....primitive consisting of six quadric planes. Each primitive exists in its own coordinate system and intersections of a ray with a primitive are obtained by transforming the ray from the world coordinate system to the coordinate system of the primitive, and then solving the equation of the quadric [Will87, Roth82]. This transformation of the ray into the coordinate system of the primitive simplifies the calculations as it is easier to transform the ray than to transform the object. Here, only point and vector transformations are important. Consider a 4 4 transformation matrix T and a point in 3space P = ....

....entry exit and the object id lists are sorted in order of ascending t values. When a combination operator is encountered the top two entry exit lists are popped off and passed to a COMBINE module which applies the operator to them. The primitives are combined according to an in out classification [Roth82]. This means classifying the parts of the ray which are outside the object as out, and those parts that are inside as in. The resulting list is now pushed back onto the stack. A ray classification must be generated for each branch of the CSG tree, i.e. one for the left branch and one for the ....

Roth, S.D., "Ray Casting for Modeling Solids", Computer Graphics and Image Processing, 18, pp. 109-144, 1982.

....prefix order will produce all attributes and primitives in the correct sequence for rendering them into the z buffer. Obviously this algorithm does not natively support CSG operators, therefore some CSG conversion algorithm must be applied to the DAG first. raytracing [Appe 68] A CSG raytracer [Roth 82] is already based on a hierarchical data structure and only needs to handle polygonal data as well in order to cope with the BABEL DAG BSP: As indicated earlier, an additional node can be introduced, that encodes the division of the rendering space in two halves along a given plane. Again CSG ....

Roth, S.: "Ray Casting for Modeling Solids". Computer Graphics and Image Processing 18(2), pp. 109-144, February 1982.

....of T . Our method can be implemented using simple operations, such as sorting and table look ups, and does not require any sophisticated data structures. Moreover, one can apply many of the previous heuristic techniques for speeding up CSG ray shooting to our methods, such as bounding boxes [28, 29, 47, 49, 50, 51] and face cutting [37] although none of these heuristics would improve the worst case running time. As an aid to practitioners, we also enumerate some additional heuristics that one can apply to make our method run faster in practice. Thus, we believe our method should run very fast in practice, ....

....more recently by Getto [28] who also gave some heuristics that should help this classification algorithm run faster in practice. Since classification of lines and other geometric objects (such as the CSG model s boundary) is such a fundamental problem, a considerable amount of work (e.g. see [24, 28, 29, 37, 41, 47, 48, 49, 54]) has been directed at methods for improving these running times. None of these methods run faster than O(n 2 ) in the worst case, however they are all based upon heuristics that should work well in practice but do not improve the worst case running time. Some methods have running times that ....

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S. D. Roth, "Ray casting for modeling solids," Computer Graphics and Image Processing, 18, 109--144, 1982.

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Roth, S., "Ray casting for modeling solids," Comp. Graph. Im. Proc., 18, pp. 109--144, 1982.

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Roth, S.D., "Ray Casting for Modeling Solids," Computer Graphics and Image Processing, 18, pp. 109-144 (1982).

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Roth, S. D., "Ray Casting for Modeling Solids." Computer Graphics and Image Processsing, 18 (February 1982), 109144.

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Roth, Scott D. "Ray Casting for Modeling Solids." Computer Graphics and Image Processing, Vol. 18, 1982, p. 109-144. f4g

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S. D. Roth, "Ray casting for modeling solids", Computer Graphics and Image Processing, 18(2), pp. 109--144 (1982).

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S. D. Roth, "Ray Casting for Modeling Solids," Computer Graphics and Image Processing, 18, pp. 109-144, 1982.

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Roth, Scott D., "Ray Casting for Modeling Solids." Com- . 1 puter Graphics and Image Processing, vol. 18, no. 2, Feb 982, pp. 109-144. Rubin, S. M., and Turner Whitted, "A 3-Dimensional C Representation for Fast Rendering of Complex Scenes." omputer Graphics (SIGGRAPH '80 Proceedings), vol. 14, S no. 3, July 1980, pp. 110-116.

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