CGTalk - Mia transperancy/shadow problem.

View Full Version : Mia transperancy/shadow problem.

kpoint

01-19-2010, 02:00 AM

I know this is the most asked question, but my problem is a bit different.

http://img524.imageshack.us/img524/9335/miatransshadows.th.jpg (http://img524.imageshack.us/i/miatransshadows.jpg/)

So one things bothers me: I have blue shadows (????wft????)

I have Mia_x.result(Thinglass preset) connected to base color of mix8layer. In Layer1.color respectivly o.factor i have image(.psd or .tga, tried both) with alpha channel. Mix8Layer shader is connected in both material shader and shadow shader slots of the shading group.
MR settings: refl=10, refr=10,shadows= 10, MAx trace depth = 30. Pass custom alpha ON. Shadows - segmented.

Pls help 'cause i'm going to kill my computer soon. I can upload my scene if that would help. Thanks in advance.

PS: I forgot. It's Maya 2009 x64

Kev3D

01-19-2010, 02:28 AM

Well, the shadow is blue because it looks like the material has a blue in it. What are you after? a solid black shadow or caustics?

edit: Just had another look at the render, are you talking about shadow of the word Lyrica?

kpoint

01-19-2010, 09:41 AM

Yes, solid black shadow. This text supposed to be opaque. In my first post i forgot to increase ray depth limit on spot light. Here it is:

http://img710.imageshack.us/img710/7861/miatransshadows4.th.jpg (http://img710.imageshack.us/i/miatransshadows4.jpg/)

Kev3D

01-19-2010, 01:37 PM

Sorry, the answer isn't obvious to me, I'm having trouble envisioning how you have this set up, maybe uploading the scene file would be a good idea?

kpoint

01-19-2010, 01:38 PM

OK. I think i found the solution. I'll post here the network if anyone found it useful.

http://img503.imageshack.us/img503/2272/miaglasstransperanttext.th.jpg (http://img503.imageshack.us/i/miaglasstransperanttext.jpg/)

The texture is .psd, but i guess it will work well with .tga or .tiff. Has no transparency, just alpha channel. It's middle-mouse-draged into diffuse slot of mia. Texture's out_alpha is connected to reverse node which output is connected to transparency in mia.

Confusing thing for me was that i have to invert the alpha channel to connect it to the transparency in mia. Somehow maya understand right where is the alpha for the diff slot, but it's the opposite for the transparency.

Anyway it work perfectly for both refractive coustics and tranparent shadows.

InfernalDarkness

01-19-2010, 08:29 PM

You should be using "Cutout Opacity" instead of the transparency channel, in your mia_material_x. With the base blinn/phong Maya materials, there's no separate slot for cutout opacity, but with mia_material_x, it really works wonders.

This way you have control over your cutout separately, and still have all your regular transparency functions too!

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