Real-time interactive visibility computation for quadratic surfaces

Abstract

The display of a three-dimensional scene consisting of a collection of analytically defined surfaces is accomplished via a projection mapping into the viewing plane. Ray casting is a technique which accomplishes this mapping by firing a mapping ray through each pixel of the screen into the world space. The result is the intersection points of this ray with each of the surfaces. The intersection points so found are further tested in order to determine which one is visible.

Real-time interactive graphics requires that the image be updated fast enough so that the display seems to present fluid or real time motion to the viewer. Given that the refresh of the image takes place approximately every (1/30) of a second, the determination of the above mentioned intersections should take place in this interval of time.

In this paper we present a VSLI-oriented algorithm that determines the intersection points of the mapping rays with a quadratic surface as well as the visible points. A simple shading model is presented and a VSLI architecture is briefly discussed.

Keywords:

• Algorithms
• object modeling
• shading