pwh@bradley.UUCP (06/28/90)
What are the spectral properties of glass that I could use in a raytracing program? (have MTV and Rayshade, either nff or the Rayshade description language would be fine, but I'd prefer nff) I've a friend who's been working on the problem for a while now, and it's given some interesting results, but nothing that actually looks like glass.... ---------------------------------------------------------------------------- ...uiucdcs\ Pete Hartman ......noao >!bradley!pwh ......cepu/ INTERNET: pwh@bradley.edu ARPA: cepu!bradley!pwh@seas.ucla.edu
mkelly@comix.cs.uoregon.edu (Michael A. Kelly) (07/01/90)
In article <8600001@bradley> pwh@bradley.UUCP writes: > >What are the spectral properties of glass >that I could use in a raytracing program? Try "Color Science" by Wyszecki & Stiles (1982). I don't have the book with me but I'm pretty sure it has the information you need. Mike.
musgrave-forest@CS.YALE.EDU (F. Ken Musgrave) (07/01/90)
In article <8600001@bradley> pwh@bradley.UUCP writes: > >What are the spectral properties of glass >that I could use in a raytracing program? > >I've a friend who's been working on the problem >for a while now, and it's given some interesting results, >but nothing that actually looks like glass.... Glass is not so easy to do - I got a Master's degree for doing it! Three things are necessary: (1) The proper index of refraction (1.5-1.9). (2) The proper reflection function - Fresnel's Law. (3) Dispersion. Also, you should propagate rays spawned by total internal reflection - many ray tracers quash such rays outright; this can lead to ugly artifacts in (glass) objects with planar surfaces. The first two things can be standard features in a ray tracer, the third is uncommon. There are two published solutions (that I know of): Thomas, S. W., "Dispersive Refraction in Ray Tracing", Visual Computer, vol. 2, no. 1, pp 3-8, Springer Int'l, Jan. '86 Musgrave, F. K., "Prisms and Rainbows: a Dispersion Model for Computer Graphics", Proceedings of the Graphics Interface '89, London, Canada, June '89 Neither of these references is easy to get. Perhaps UC Santa Cruz would provide a copy of my thesis: Musgrave, F. K., "A Realistic Model of Refraction for Computer Graphics", Master's Thesis, UC Santa Cruz, Santa Cruz CA, Sept. '87 As an alternative, I will put the troff sources for my GI paper where you can get them via anonymous ftp on weedeater.math.yale.edu - but you won't get any of the nice illustrations. At any rate to get dispersion into a ray tracer requires some hacking, and will in general slow down the rendering a *lot*. Thomas & I used quite different approaches; his would probably be faster for scenes without much dispersion, and vice-versa. A future version of Craig Kolb's RayShade may feature dispersion... (I'm not at liberty to distribute my ray tracer with dispersion.) Ken *===============================================================* F. Kenton ("Ken") Musgrave arpanet: musgrave-forest@yale.edu Yale U Depts of Math and CS (203) 432-4016 Box 2155 Yale Station Primary Metaphysical Principle: New Haven, CT 06520 Deus ex machina *===============================================================*
3ksnn64@cadlab1.ecn.purdue.edu (Joe Cychosz) (07/06/90)
In article <8600001@bradley> pwh@bradley.UUCP writes: > >What are the spectral properties of glass >that I could use in a raytracing program? One thing to keep in mind, glass is usually about 4% reflective.