WIEGAND, T. F. 1996. Interactive rendering of CSG models, Computer Graphics Forum, 15, 4, 249-261.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....decomposed in a certain line style and material for OpenGL. In comparison, a nonphotorealistic renderer might interpret the attribute directly. 5 Multi Pass Rendering Multi pass rendering is one characteristic element of hardware accelerated shading, lighting, and modeling techniques [6] 7] 10][16] that implement, for example, high quality illumination models, bump mapping, and image space CSG modeling. In generalized scene graphs, techniques implement multi pass rendering. A technique defines one or more rendering passes, and it takes control over the evaluation of shapes and attributes. ....

T.F. Wiegand, "Interactive Rendering of CSG Models", Computer Graphics forum 15(4):249-261, 1996.

.... 99, HZLM01] An algorithm to compute a discretized approximation to the convolution of general polyhedral models using the rasterization hardware is presented in [KR92] Algorithms for direct rendering of CSG models based on graphics rasterization hardware have been presented in [EJR89, GHF86, Wie96] They render the CSG hierarchies using multiple passes of clipping (i.e. stencil tests) and depth tests. 3 Background and Overview In this section, we give a brief overview of the PD computation problem and our approach to solve it. 3.1 Penetration Depth Let P and Q be two intersecting ....

T F Wiegand. Interactive rendering of csg models. Computer Graphics Forum, 15(4):249--261, 1996.

....for geometric design or machining simulation. The relative simplicity and robustness of implementation, the interactive flexibility of dynamic CSG trees, and the potential for pixel parallelisation[Molna88] make image space algorithms attractive for some applications. Existing CSG rendering methods[Goldf89, Wiega96, Rappo97, Stewa00] generally require time, where is the number of leaf nodes in the CSG tree. This requirement is due to the general strategy of comparing every pair of objects. This can be improved by taking advantage of depth complexity[Stewa98] the number of objects covering each pixel) ....

.... a common bottleneck in contemporary graph Convex Cylinders and z buffer Draw furthest front faces z buffer Count back facing surfaces behind stencil buffer Reset pixels where stencil z buffer Figure 1: Z Buffer Intersection using the z and stencil buffers ics hardware[Wiega96, Stewa98, Stewa00]. This paper introduces a new approach for rendering the intersection of convex objects in linear time, that we call SCS Intersect. It has been implemented using the z and stencil testing functionality of OpenGL[Boarda, Boardb] SCS Intersect can be used as a stand alone algorithm for CSG trees ....

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T. F. Wiegand. Interactive rendering of CSG models. Computer Graphics Forum, 15(4):249--261, Oct 1996.

....in this paper, we will still refer to this extended model as CSG model. Due to the lack of explicit representation of surface boundaries, CSG display is not directly supported by standard graphics systems. Although several interactive CSG rendering algorithms have previously been developed [8, 13, 17, 20], they cannot be directly applied when volume data sets are involved. In principle, there are two potential solutions for the rendering of volumetric CSG models. The first is to explicitly extract an iso surface from the volume data set, and convert the model into a regular geometric CSG model, ....

T. F. Wiegand. Interactive rendering of CSG models. Computer Graphics Forum, 15(4):249--261, 1996.

....single products and the sum of products is build with help of the depth buffer by sequentially rendering the products. Therefore normalization is not an important issue to understand the following and its discussion is omitted. Detailed information on normalization can be found in [1] 2] and [6]. 3 Goldfeather The base for all algorithms in this paper is the work from Goldfeather, Molnar, Turk and Fuchs who developed an algorithm which is known as Goldfeather and is described in [1] and [2] Wiegand adapted this algorithm for usage with OpenGL [6] The basic idea is to render each ....

.... can be found in [1] 2] and [6] 3 Goldfeather The base for all algorithms in this paper is the work from Goldfeather, Molnar, Turk and Fuchs who developed an algorithm which is known as Goldfeather and is described in [1] and [2] Wiegand adapted this algorithm for usage with OpenGL [6] . The basic idea is to render each primitive of a product as usual and to afterwards clear all the pixels which do not meet the CSG conditions. The decision which pixels to clear can be made with a simple parity test (see below) All other primitives of the product are tested against the surface ....

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T. F. Wiegand. Interactive rendering of CSG models. Computer Graphics Forum, 15(4):249-- 261, October 1996.

....graphics techniques, such as volume rendering and voxelization, have been attracting enormous research attention recently. But they have not yet played a significant role in solid modeling and its CAD CAM applications. Although there have been many fast rendering algorithms for CSG models[6, 9], volume based techniques have the benefit of explicitly generating the volume representations for the CSG models, which can be very useful for many volume related operations such as volume rendering, integral property computation, finite element analysis and layered manufacturing for rapid ....

T. F. Wiegand. Interactive rendering of CSG models. Computer Graphics Forum, 15(4):249--261, 1996.

....and Z buffer based techniques. Z buffer methods utilise the standard Zbuffer algorithm implemented in conventional graphics hardware in order to render a CSG hierarchy using multiple passes of clipping (stencil test) and depth sorting (depth test) operations. Such algorithms are proposed in [Goldf86, Epste89, Wiega96, Stewa98, Stewa00]. A key point to the Z buffer CSG rendering techniques is the conversion of the initial arbitrary CSG tree into a normalised CSG tree. A CSG tree is normalised when it is transformed in a sum ofproducts form (union of primitive differences or intersections) A product may consist of a primitive ....

....(union of primitive differences or intersections) A product may consist of a primitive and a normalised CSG sub tree. A representative algorithm of the Z bufferbased CSG rendering category is the one proposed by Goldfeather et al. [Goldf86] and implemented in non specialised hardware by Wiegand [Wiega96]. In this algorithm, after bringing the CSG hierarchy in the form of a normalised CSG tree, each (convex) primitive surface is clipped in image space by its siblings using the depth and stencil tests. The partial surfaces are finally merged with a simple Z buffer operation (z less than) Fig. 2) ....

Wiegand,T.F.: Interactive Rendering of CSG Models, Computer Graphics Forum, Blackwell Publishers, Vol.15, No.4, pp. 249261, 1996.

....rendering pipeline, or maintaining lists of surfaces at each scanline and performing clipping over spans of pixels. The disadvantages of scan line CSG rendering are that the solution is view dependent and that the technique is not supported in conventional graphics hardware. Z Buffer Algorithms [5, 6, 16, 3, 15] Surfaces are clipped in a zbuffer by a multiple pass algorithm. Arbitrary CSG trees are handled by tree normalisation and pruning techniques. 6] Methods exist to support non convex primitives. The advantage of z buffer algorithms is that no b rep clipping is required, and the approach can take ....

....RENDERING Arbitrary CSG trees can be rendered in standard z buffered architecture using techniques described by J. Goldfeather. 6] Whilst the approach was originally developed for the Pixel Planes graphics architecture[5, 9, 4, 8] it has recently been adapted to the OpenGL graphics environment. [16] The approach is based on the ideas of surface parity, tree normalisation, and z buffer surface clipping. We refer to these concepts collectively as Goldfeather CSG Rendering. We discuss each aspect in the following subsections. 3.1 Parity Surface parity refers to whether a surface in the ....

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T. F. Wiegand "Interactive Rendering of CSG Models" Computer Graphics Forum, Vol. 15, No. 4, Oct. 1996, pp. 249-261

....Jansen86, Jansen87, Goldfeather89, Rossignac90, Jansen91] These methods do support real time rendering of CSG models (naturally, depending upon the model size) but are not practical for every day use because they require expensive special purpose hardware that is not easily available. [Wiegand96] presents a method to emulate the algorithm of [Goldfeather89 ] designed for a parallel pixel based architecture, on standard graphics hardware. In effect, double z and image buffers are emulated by using multiple passes and memory copying. This method, and a similar method detailed in ....

....uncommon. In addition, the brute force methods do not support many kinds of geometric acceleration schemes. In summary, none of the existing methods fulfills the goal of interactive display of CSG models while using standard graphics hardware. The methods that partially support that goal (e.g. [Wiegand96 ]) do not make efficient use of the overall architecture and are too low level and brute force to provide satisfactory support for conceptual design. Proposed approach. In this paper we present a method for displaying CSG models, which is particularly attractive for conceptual design. The method ....

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Wiegand, T.F., Interactive rendering of CSG models. Computer Graphics Forum, 15(4):249--261, 1996.

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WIEGAND, T. F. 1996. Interactive rendering of CSG models, Computer Graphics Forum, 15, 4, 249-261.

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T.F. Wiegand, "Interactive rendering of CSG models," Computer Graphics Forum, vol. 15, no. 4, pp. 249--261, 1996.

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T. F. Wiegand. Interactive Rendering of CSG Models. Computer Graphics Forum, 15(4):249--261, 1996.

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T. F. Wiegand. Interactive Rendering of CSG Models. Computer Graphics Forum, 15(4):249--261, 1996.

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T. Wiegand. Interactive rendering of CSG models. Computer Graphics Forum, 15(4):249--261, 1996.

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