Apache animation: MR Black artifacts?

# 1 26-03-2005 , 04:43 PM

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This is my first post, which goes to show how good the Apache tutorial really is. But I have come across a problem that I cannot resolve, and it's to do with Mental Ray. I am on pt4 of the animation series and am trying to render the chopper, but no matter what settings I use (on my 3rd day of trying variations) I can't get rid of some black artifacts that have appeared as indicated in the included image. It seems to have something to do with the tyres and there are some black dots on the end of some of missile tips? I have gone back to a previously saved file and redone the procedure in part 4 several times and the problem always comes back? There aren't any nurbs in my model and it is pure poly and my shaders aren't anything too funky. To be honest I have searched elsewhere for some tips for M.R and have discovered that it can produce these kinds of results for various reasons, most of which are mysterious, so I am a bit sick of trying to get this right by using it anymore. Can I light my scene conventionally and render the chopper with Maya? This is only the 3rd model I have made and I have only been using Maya (or any 3D software) for 4 months, so I have a lot to learn about lighting too. Any suggestions Mister Brown? and thank you for a fantastic tute, that has been a Baptism by fire for me.
Smokey B

THIS IS A BIG PS: I also sometimes get an error which reads "[Mayatomr.Shader] : singleShadingSwitch1: array attribute is empty" if that may be anything to do with it?

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Last edited by smokeyb; 26-03-2005 at 05:12 PM.

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# 2 26-03-2005 , 07:12 PM

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My first guess would have been that the final gathering is causing the artifacts. This still might be the case so I'd try to tweak the FG settings (namely min/max radius). The error you're getting might be the problem too. Have you checked your shader networks if there's something odd going on? For example the 3d paint texture tool might screw them up so the mayaToMr can't understand it.

Kari
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# 3 26-03-2005 , 07:13 PM

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Do the artifacts appear always exactly in the same place even if you render from completely other angle?

Kari
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- My IMDB

Do a lot, Fail a lot and Learn a lot!

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# 4 26-03-2005 , 07:55 PM

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Actually, the artifacts shift position in a few places, when I change the shader 1 particular object? I mean, when I changed my tyre texture to a bog standard blinn, it got rid of some of the black on the tyre and also some black bits off the rocket launcher and chassis? Could that have something to do with reflections? Anyway, can I light this scene and render it with Maya software, as you did with the other renders? I want to find out why it's happening in M.R but I haven't got another 3 days to try different settings that never seem to make any difference to speak of. I am convinced it is a shader issue in some form or another, but I can't find anything that might be causing this, or at least I cant find it easily. And if it is a shader issue, why would parts of the shaded object render ok and some parts don't? That would go back to the lighting wouldn't it? I was hoping this last part would be relatively easy and I know it has nothing to do with you or your tutorial, but I am desperate to find a work-around.
Thanks for your help.
Smokey B

There are 11 types of people in the world, those you understand binary, those who don't and those who have a life (my own variation)

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# 5 26-03-2005 , 09:28 PM

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I seem to have it sorted now, by deleting all the shaders I created for my still shots. A couple of them I dowloaded and modified from various sources, and they did indeed cause problems for M.R. I now have my file textures and the black material shader you use in the tutorial, in 3 various shades (blasck, dark grey and light grey). All my black artifacts have gone but the Chopper looks a little boring now. Thanks for the advice which helped to resolve this issue.
Smokey B

There are 11 types of people in the world, those you understand binary, those who don't and those who have a life (my own variation)

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