View Full Version : Alpha chammel in MR + passes!
04-05-2004, 03:44 PM
Hi everybody. Really need help. Please : Does anybody know how to set Mental Ray to render Alpha channel? Maybe I should connect output shader to my camera... But there is no avaible shader. Also have problems with rendering in passes and layers: MR doesn't want to render all passes into subdirectories, it just renderes first pass I selected (for example ops_shadow_tmp.jpg) and no more. Thx in advance.
04-05-2004, 04:17 PM
Does anybody know how to set Mental Ray to render Alpha channel?
It does this automatically. Just make sure you have "RGB Channels" and "Alpha Channels" checked in the render globals (which should already be checked).
R doesn't want to render all passes into subdirectories, it just renderes first pass I selected (for example ops_shadow_tmp.jpg) and no more
This problem has been addressed already on the forum. You need to create your subdirectories manually before you render. For more info, do a topic search on this forum.
04-05-2004, 04:47 PM
Hm... Thx but I just"can't check these boxes. Maybe all problems is in camera.
04-05-2004, 05:24 PM
1- It is a bug in mr for maya. If you using custom mr shaders, alpha channel doesn't render. Checking "pass surface color alpha channel" option can help, but not always. I think it is a type mismatch between Maya color type (rgb) and mental ray color type (rgba).
2-It'a a bug too. You should create subdirectories before render.
-Sorry for my terrible English.
04-05-2004, 05:41 PM
yeah, I suggested... so I just can't render my alpha channel? Maybe some plugins... Really don't know waht to say, I have really big problems! :) Maybe someone knows what are these output shaders for?
04-05-2004, 08:46 PM
You can always render a mask pass, using white surface shaders etc. But this will not work with refraction :shrug:
Output shaders're for post effects, like 2d motion blur, glow etc.
04-06-2004, 09:40 AM
we had an discussion on the 2nd problem a while ago:
there was a quite helpful link to an highend thread on the second page. But as already said, it doesnt work for refractions.
04-06-2004, 03:26 PM
Thx!!! But in my case I need alpha tight in refraction scene! I'll try more... Thx again.
01-17-2006, 11:00 PM
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