Gouraud Shading Research Articles

Real World Graphics Launches Super Reality

REAL World Graphics has formally launched its new range of high preformance real time 3D image generators aimed at the visual simulation and animation markets. Known as Super Reality, these modular and scaleble systems use parallel arrays of Intel i860 RISC microprocessors running at 40MHz to achieve remarkable price/ performance characteristics. Super Reality offers such features as photo‐texturing, antialiasing and Gouraud shading at a cost which puts graphics supercomputing within reach of those who previously could not afford it. All systems and graphics functions are programmed in ‘C’ making Super Reality a totally flexible product that could be easily applied to other applications such as general array processing.

Methods and applications of three-dimensional imaging in orthopedics

Computed tomography is a commonly used technique for detecting pathological alterations in soft tissues and the skeleton. Three-dimensional images of the skeleton are very useful for planning surgical treatment and monitoring therapy, but unfortunately mental reconstruction of complex three-dimensional anatomical structures from conventional tomography is very difficult. This article describes a process by which automated analysis of the regions of interest in the computed tomographic (CT) images yields the contours of the surfaces which can be presented pseudo-three-dimensionally using Phong's lighting model and Gouraud's shading methods. Three applications in the areas of orthopedics and neurosurgery demonstrate the efficacy of the method.

Distributed graphics: where to draw the lines?

Distributed graphics: where to draw the lines?

3D Images of Molecular Properties by Triangulation of Contour Lines

AbstractComputer programs have been developed to display molecular properties on a raster scan device, both as 2D colour‐filled contour maps and as 3D solid models. Starting from 2D contour values calculated in parallel molecular grids, a triangulation algorithm, based on the connection of contours lying in successive planes, is applied for generating 3D solid models displayed with Gouraud shading. These methods of presentation have proved to be very useful for demonstrating the main features of chemical bonding and molecular reactivity.

Data processing for scanning tunneling microscopy

This contribution deals with the data processing system for our scanning tunneling microscope (STM). Since several collaborators should have access to our STM data, we have decided to separate between data acquisition and data processing. The data acquisition system based on a cheap 8-bit microcomputer controls all aspects of the scanning process, stores the data on disk, and transmits them to the data processing system. Image processing and computer graphics have become more important in scanning tunneling microscopy. We use two μVAX II’s which are connected by a network, one as a storage device (527-MByte disk), the other as a graphic processor (256 colors). We have developed a highly interactive software package which allows manipulating and displaying the STM data. This package includes utilities to fit a plane or a hyperbolic paraboloid and subtract it from the image. The line plots of topography and the local barrier height can be viewed from different point of view. Top-view images can be displayed both in color with different color lookup tables, which can be chosen interactively, and in gray scale. The images can be displayed at higher resolution by a bilinear interpolation. Light sources illuminate the surface to get flat and Gouraud shading. The shading can be combined with perspective or parallel projection and hidden surface removal. There is also a fast Fourier transformation algorithm and a utility for interactive digital filter design implemented. There are utilities to create stereoscopic pictures. Significant examples of the application to images of graphite and of nanometer scale structure images are presented.

Image rendering by adaptive refinement

This paper describes techniques for improving the performance of image rendering on personal workstations by using CPU cycles going idle while the user is examining a static image on the screen. In that spirit, we believe that a renderer's work is never done . Our goal is to convey the most information to the user as early as possible, with image quality constantly improving with time. We do this by first generating a crude image rapidly and then adaptively refining it where necessary as long as the user does not change viewing parameters. The renderer operates in a succession of phases, first displaying only vertices of polygons, next polygon edges, then flat shading polygons, then shadowing polygons, then Gouraud shading polygons, then Phong shading polygons, and finally anti-aliasing. Performance is enhanced by each phase using results from previous phases and trimming the amount of data needed by the next phase. In this way, only a fraction of the pixels in an image may be Phong shaded while the rest may be Gouraud or flat shaded. Similarly anti-aliasing is performed only on pixels around which there is significant color change. The system features fast response to user intervention, encourages user intervention at any moment, and makes useful the idle cycles in a personal computer.

Smoothly shaded renderings of polyhedral objects on raster displays

The appearance of raster-scan renderings of polyhedral approximations to curved surfaces can be enhanced greatly by shading them in a manner that varies smoothly across each polygon and which matches the correct shade at each vertex. Henri Gouraud and Bui Tuong-Phong have previously described two methods of computing such shading functions. While the computations in Gouraud's method are quite quick to perform, the renderings produced often exhibit pronounced Mach bands, and animated sequences tend to have annoying fluctuations in intensity. Phong's method tries to cure these problems, but is much more expensive computationally. We will show a new, faster method of computing Phong shading, and discuss the relationship of this method to Gouraud shading. We will also exhibit representatives of a class of surfaces for which Phong shading surprisingly produces worse Mach bands than Gouraud shading.