For a discussion of modeling and raytracing within BRL-CAD, see:

M. Muuss, ``Understanding the Preparation and Analysis of Solid Models'', in ``Techniques for Computer Graphics'', ed: Rogers & Earnshaw, Springer Verlag, New York, pages 109-172.

Also in ``The Ballistic Research Laboratory CAD Package Release 4.0 Manuals, Volume V, Analyst's Manual'' Page V5S08A05.

For a discussion of the rt lighting model see:

M. Muuss and P. Dykstra, ``The RT Lighting Model''. in Proceedings of the BRL-CAD Symposium '88, held at the Ballistic Research Laboratory, Aberdeen Proving Ground, Maryland, June 28, 1988.

Also in ``The Ballistic Research Laboratory CAD Package Release 4.0 Manuals, Volume V, Analyst's Manual'' Page V5S10A03.