Integrating 3D models with photography
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# 1 15-10-2005 , 06:37 AM
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Join Date: Oct 2005
Posts: 6

Dielectric Material and Transparent Shadows?

hi @ all. first: i am new to this forum and i would like to say hello to everybody in here user added image i'm a german so please be aware of my english capabilities user added image)

ok so now my problem: i use maya and i would like to use mental-ray for creating a nice piece of glass. so i assign a standard blinn or phong material to the glass, go to it's shading group and assign a custom shader to the material slot ... of course: a dielectric material user added image this gives me the look i want to achieve - but probably not the shadows i expect from a real glass surface user added image after assigning the dielectric material in the shading-group, my transparent shadows are gone although i have activated the raytrace-shadow and generously raised up the trace-values.

i have studied several workarounds for that (for example assigning a custom shadow shader (the transparent one) and connecting the IOR of the dielectric to it's transparency) but everything dont work. my question now is: how can i get beautiful transparent shadows which are based on the IOR of the dielectric material (which normally is the natural behavior) ??? it would be great, if someone has a solution for me !!!

many thanks !!!!
s2k


illuminate ... and wait
# 2 15-10-2005 , 05:32 PM
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Join Date: Oct 2005
Posts: 6
well ... here are some images for comparison. a torus, with a dielectric material assigned to it and a spot-light which casts the light. and for comparison the same scene again rendered with brazil ... and there you can see those transparent shadows which i would like to achieve with mental-ray too:

mr dielectric-material: https://www.subbz2k.com/misc/torus_mr.jpg
brazil glass-material: https://www.subbz2k.com/misc/torus_brazil.jpg

these 2 images are all rendered in the same conditions within 3ds max. i reduced the overall quality to improve the render speed but the differences should be seen. with the brazil rendering you can see those transparent shadows which are generated by a simulated area-light. notice that they are generated within the surface too (what a beatiful natural behavior user added image ). in the mental-ray rendering you see a sharp edged raytrace shadow (because within 3ds max i have to change the light-source to generate area-lights with mental-ray but this is incompatible with brazil so i left off) but the important thing is the absolutely black shadow: that's not correct.

so again: can somebody tell me, how to get those transparent shadows with the dielectric material as shown in the rendering from brazil ??

plz help i'm out of ideas user added image


illuminate ... and wait

Last edited by subbz2k; 15-10-2005 at 05:38 PM.
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