Compositing 3-D rendered images

We propose a new rendering technique that produces 3-D images with enhanced visual comprehensibility. Shape features can be readily understood if certain geometric properties are enhanced. To achieve this, we develop drawing algorithms for discontinuities, edges, contour lines, and curved hatching. All of them are realized with 2-D image processing operations instead of line tracking processes, so that they can be efficiently combined with conventional surface rendering algorithms. Data about the geometric properties of the surfaces are preserved as Geometric Buffers (G-buffers). Each G-buffer contains one geometric property such as the depth or the normal vector of each pixel. By using G-buffers as intermediate results, artificial enhancement processes are separated from geometric processes (projection and hidden surface removal) and physical processes (shading and texture mapping), and performed as postprocesses. This permits a user to rapidly examine various combinations of enhancement techniques without excessive recompntation, and easily obtain the most comprehensible image. Our method can be widely applied for various purposes. Several of these, edge enhancement, line drawing illustrations, topographical maps, medical imaging, and surface analysis, are presented in this paper.

Ieee Computer Graphics and Applications, 1984

1986

This dissertation explores the use of an analytic visibility algorithm for the high-speed generation of anti-aliased images with textures. Wben visibility is known analytically before any sampling takes place, low-pass filtering for anti-aliasing can be done to arbitrary accuracy at a cost proportionate to the output resolution. Furthermore, since the filtering and sampling processes can be expressed as a set of integrations over the image plane, the filtering process can be decomposed into a set of sums of integrations over each visible surface in the image plane, allowing the rendering of each visible surface to be done in parallel using an image buffer to accumulate the results. Thus, analytic visibility can serve as the basis for high-speed, high-quality image synthesis. In this dissertation, algorithms for computing analytic visibility and for producing filtered renderings from the resulting visible surfaces are presented. In order to provide real-time performance, these algorithms have been designed for parallel execution on simple concurrent structures. Architectures based on these algorithms are presented and simulated to produce expected execution times on a set of test Images. * Look for the environment associated with the list * containing the polygon. *I Environment -EnvironmentSean:h(ListiD); if (Environment--NULL) { } I* * If not found, this list was passed on through this node *I Copy the input to the output n:tum; Move the dividing plane equation from the environment block to registers for fast evaluation of ax+by-+<:z+d Read the ;:KJlygon header into local memory. When the clipping o~tion completes we may have to send the header information along with both fragments I* * Now we start t.'le clipping algorithm. First the vertex list is • read into local memory. As each vertex is encountered the inner * product of the vertex with the dividing plane plane is evaluated and • the side determination: + side, -side, or clipped, is made.

Abstract�Transparency and anti-aliasing are crucial to enhance realism in computer-generated images, which have a high demand for such effects. Transparency is largely used to denote relationships among objects in a scene, and to render several structures, such as particles and foliage. Anti-aliasing (AA) is also important, since jagged edges can be easily spotted and create disruptive distractions during a scene walkthrough, which are unacceptable in real-time applications. Figure 1 illustrates both effects.

1997

Mathematica is an integrated environment for symbolic transformation of mathematical formulas. This environment has applications in scientific computing, scientific visualization and education. Mathematica gives possibility to describe visualized objects in form of mathematical formulas and expressions. Such descriptions are more clear and concise than low-level C or C++ code. Many visualization systems require input in the form of (sometimes huge) data files, which is a disadvantage for highly interactive and animated 3D graphics applications. This is also the case for graphics expressed in Mathematica which is computed interpretively and saved in a static data form before display. This causes low graphic performance. In this paper we describe an approach which uses object geometry descriptions in the form of efficient program code instead of huge data files. We have built a tool that produces 3D visualizations of geometrical objects and object trajectories from mathematical specifications expressed as parametric functions in Mathematica. A compiler has been developed which generates efficient C++ code from such functions and symbolic expressions. This code is linked together with a powerful 3D browsing environment and uses OpenGL with possible hardware support. All the computations are performed within the visualizing application. Object geometry, color, etc. can be changed dynamically during animations. Thus the flexibility of interactive exploration of 3D scenes and animation become available for the end-user.