CGTalk - Some question about radiosity and LightScape.

View Full Version : Some question about radiosity and LightScape.

michaeli

03-17-2004, 04:03 PM

I heard that one of the shortcomings of the raidosity is that they can only compute direct and indirect illumination on rough surfaces and cannot render glossy, reflective or transparent refractive surfaces nor caustics caused by those surfaces. But I have seen lots of "glossy, reflective or transparent refractive surfaces" objects such as glass and high reflective floors in Lightscape's scene, which use radiosity to render, and looks good. So I'm curious that how LS deal with those surfaces ?

And I also heard that the materials systems in LS are not surface shade model as other applications do but some physical based materials systems, is that true? What does that physical based materials system mean?

vislaw

10-06-2004, 02:01 AM

Lightscape includes a raytracer specifically for the purpose of handling reflection/refraction stuff as well as accurate shadows. To generate polished renders the scene is rendered using the radiosity algorithm combined with raytracing for the applicable surfaces.

Mark

shehbahn

10-06-2004, 02:30 AM

>What does that physical based materials system mean?

I am guessing here : BRDF functions applied in the shaders instead of being analytical approximations are based on actual materials. IIRC LS (or is it Radiance ?) comes with a spectral database of thousands of natural & artificial light sources. If that's the case, most of their BRDFs are probably computed for the full light spectrum instead of RGB tristimulus space that most other renderers work in. The difference is subtle but noticeable. It also makes the rendering of light diffraction much easier (if slow).

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