Conceptual Modelling


ABSTRACT
Traditionally, the initial concepting in solid-modelling design occurs with pen and ink on paper. This arcane process greatly restricts the modeller because of the media being employed. As described in http://www.cs.huji.ac.il/~arir/cda-abs.html, conceptual design with the aid of a three-dimensional computer interface will allow the modeller to better design the initial stages of a solid. Since conceptual design aims at model prototyping, standard primitives in a Constructive Solid Geometry setting [hoffman89,fvd90] are employed at allow for quick manipulation. For quickness in rendering, the Convex Differences Aggregate representation of a CSG model is used. The original structure of the CSG tree is never lost allowing for export using an external ray-tracer, or boundary-representation of the final solid.

Grabs



State of the System

Currently, the system is capable of performing regularized boolean operations on cubes, cylinders, and spheres. As can be seen in the screen grabs, the system employs a 2-paned WIMP interface: window 1 contains the CSG tree and window 2 contains the model projected with perspective. It has been developed on 32-bit architecture using the OpenGL API (MESA) and GLUT on linux. I have not yet run tests or anaylsis to determine the effective speed of the interface when the user attempts to perform complex boolean operations on a tree of depth more than a few primitives large; however, initial experimentation indicates promising results.


References

Rappoport and Spitz's Siggraph '97 paper on Convex Differences Aggregate
A CSG w/ Stencil Buffer from Siggragh '97 course
A CSG w/ Stencil Buffer from Siggraph '96 course
A similar project by Pedro Sander

home
last updated: 2001.05.20; © jcorso