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The dispersion effect in Vray 2 appears to effect the alpha of refractive objects.
For example I render an image of a diamond without dispersion, and on a black background (exr - RGBA - 32bit). I take this into After effects and am able to drop it over any image and the diamond is vibrant and shiny, couldn’t be better!
Back to Max, I turn on dispersion for the diamond’s VrayMaterial (Abbe default: 50) and render again. The result in the vray frame buffer looks similar but with a slight change in apparent refraction details (no problem there) and of course the added rainbow dispersion patterns which look great!
The problem is in the alpha channel which was previously pure white with a few grey/black details across the diamond. It has now become near black or 90% transparent with almost no details.
When I reload the image in After effects the comp shows it as very transparent almost to the point where I can’t make out the shape of the diamond over any composited background. I can crush the alpha up to near 100% opaque with a levels effect however I now have a visible diamond with no variation in transparency details compared to how it was without the dispersion.
I have tried changing “Affect channels” in the vraymaterial refraction section to “color only” which works only as well as the above levels effect, since the alpha is rendered pure white with no transparency details at all.
Is this a known issue and is there a solution to the problem?
Thanks!
For example I render an image of a diamond without dispersion, and on a black background (exr - RGBA - 32bit). I take this into After effects and am able to drop it over any image and the diamond is vibrant and shiny, couldn’t be better!
Back to Max, I turn on dispersion for the diamond’s VrayMaterial (Abbe default: 50) and render again. The result in the vray frame buffer looks similar but with a slight change in apparent refraction details (no problem there) and of course the added rainbow dispersion patterns which look great!
The problem is in the alpha channel which was previously pure white with a few grey/black details across the diamond. It has now become near black or 90% transparent with almost no details.
When I reload the image in After effects the comp shows it as very transparent almost to the point where I can’t make out the shape of the diamond over any composited background. I can crush the alpha up to near 100% opaque with a levels effect however I now have a visible diamond with no variation in transparency details compared to how it was without the dispersion.
I have tried changing “Affect channels” in the vraymaterial refraction section to “color only” which works only as well as the above levels effect, since the alpha is rendered pure white with no transparency details at all.
Is this a known issue and is there a solution to the problem?
Thanks!
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