View Full Version : BigMuh's Diffusion shader shadow problem?!

08 August 2004, 02:49 PM
Hi all of you, I am really impressed by your shader Bigmuh thanks very much. I used the shader connected to the ambient channel of my blinn's material and mapped all the other channels to PSD file. Every thing was cool except for the shadows when i turn on shadows the skin is totally ruined at it seems that the light does not hi the object as it should be.
some area's recieve shadows and some are not. I can use dirtmap to get much realistic effect but it still does not produce enough effect and I am using also FG.
Any ides would really helps me. btw turnnig off the shadows for the skin shader is also not a good solution if there was an object between the light and skin shaded object.

any idea what causes this, I have tried changing the lights from directional to spotlight but the same results occur also I am using raytraced shadows in maya 6

08 August 2004, 01:57 PM
Now, I ve detected what cause this problem it seems that the opening of the eyes and the mouth cause light ray to pass through and produce that so dark shadows even the mouth is closed and there are eyes, teeth and gum closing those holes but there still the rays can pass and produce those shadows, any ideas please

08 August 2004, 11:06 PM
How u link diffusion shader in your shader node ?

works fine for me .

08 August 2004, 01:08 AM
well I have connected bigMuh diffusion shader to the ambient channel since if I connected it to the incadescence and use FG it will change how skin looks and there is no difference between direct light or spot light since they all gice the same result.
Can you try making your model with open eyes ball area and put some spheres to represent the eyes and then focus a spot light with raytraced shadows turned on and see if there will be dark shadows as it happened to me.

08 August 2004, 08:02 AM
the light is going through her eye holes. this happened to me a lot when i hadn't built my character's head yet. light was shining through the neck hole.

08 August 2004, 02:41 PM
I think this shader actually is good ONLY for solid meshes... for meshes with hollow parts.. mmh.. still not a good implementation... should be something that detect holes in the geometry... and get the option to render as a massive object.

you could also try to get rid of that by playing with the shadow color for the light you linked.. I put the color of the shadow equal to that of the color of the mesh.. or try to back illuminate your mesh by linking another light.. or try to map the diffusion efx with a texture.. or also try to use two diffusion shaders.. and ctrl the fading from darker and lighter parts.. but all of these.. get not really predictable results in animation.. or really it's a pain to ctrl them.


CGTalk Moderation
01 January 2006, 11:00 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.