MELTSNE@gecrdvm1.crd.ge.com (08/20/90)
Does anyone have a method/equation to calculate the approximate RGB value for
a tungsten surface as a function of temperature? I need to color a hot
surface with an appropriate color for the temperature.
Barring that, does anyone have a method/equation to convert a arbitrary
color distribution into RGB form? (I can work out the emissivity equation
for tungsten if I need to).
Kenjroth@allvax.dec.com (Jim Roth) (08/21/90)
In article <90232.084459MELTSNE@GECRDVM1.BITNET>, MELTSNE@gecrdvm1.crd.ge.com writes... >Does anyone have a method/equation to calculate the approximate RGB value for >a tungsten surface as a function of temperature? I need to color a hot >surface with an appropriate color for the temperature. > >Barring that, does anyone have a method/equation to convert a arbitrary >color distribution into RGB form? (I can work out the emissivity equation >for tungsten if I need to). Roy Halls book on illumination in computer graphics will probably have what you need. The programs you want must be available somewhere on the network, but I don't know where - they involve calculating the CIE coordinates for your surface and then calculating the RGB values which will match these coordinates. You integrate your color distribution under the CIE matching functions (as weights.) You might also find the paper "Wavelength selection for synthetic image generation" by G. Meyer, Computer Vision, Graphis & Image Processing 41 (1988) pp 57-79 to be "illuminating". You can actually make Gauss quadrature rules using the matching functions as your weights! Overkill, but a neat idea. Another standard reference is Cook & Torrence, "A Reflectance model for computer graphics", an ACM TOG paper, about 1982 or so. I have a bunch of stuff in my files but am too lazy to dig it out right now :-) However, I did make some images using these techniques and it really works - metal looks like matal and so on. - Jim