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Old 08-10-2012, 04:07 PM   #1
Daryna
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Can't get a the diffuse pass to work

I have some problems with the diffuse render pass. My scene contains one directional light and HDR lighting. Whenever I render the diffuse pass the image is blank. The only way I've got some kind of light is by turning the option "emit diffuse" on the directional light, but it doesn't seem to have any influence from HDR lighting. The reason I'm rendering diffuse is to have an object without any shadows. Maybe there is some better way to do it? Maybe it has to do with final gather. Please help
 
Old 08-13-2012, 04:53 AM   #2
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Your hdr is emitting indirect light which is why it's not contributing to the diffuse pass. You'll need an indirect pass to see it.
Are you looking for a pass that has just the diffuse map with no shading? Or a pass with just the diffuse lighting effect?
 
Old 08-13-2012, 01:57 PM   #3
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I found that turning on the Emmit Light on Indirect Lighting kind of helps with diffuse, but I have to readjust all the lights. The Indirect pass still has shadows for me. I guess diffuse without shadow works the best for me so far. Is there a way to have Indirect without shadows? I think final gather is causing them, but I don't want to turn it off. I hope I explained it right. Sorry, I'm still learning and trying to understand.
 
Old 08-13-2012, 07:06 PM   #4
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strictly speaking, "shadows" aren't an actual thing, they're a lack of light. Using Final Gather, what you're doing is sampling to see how much light is arriving at each point on a surface. So you end up with some areas that are well-lit, and some areas that are less well-lit. We call these less-lit areas shadows, but Final Gather doesn't know the difference between shadowed areas and non-shadowed areas. They're just varying amounts of light.

When you use traditional lighting, a shadow is something that is *projected* onto a surface, either through a depth map calculation or raytracing. This method allows you to have a separate pass for light and shadow.
 
Old 08-14-2012, 05:14 AM   #5
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Quote:
Originally Posted by Daryna
I found that turning on the Emmit Light on Indirect Lighting kind of helps with diffuse, but I have to readjust all the lights. The Indirect pass still has shadows for me. I guess diffuse without shadow works the best for me so far. Is there a way to have Indirect without shadows? I think final gather is causing them, but I don't want to turn it off. I hope I explained it right. Sorry, I'm still learning and trying to understand.


That's unusual. If anything the indirect pass should have very soft lighting with soft "shadows". I put shadows in quotation marks because they aren't shadows in the traditional sense, where they need to be calculated as a raytraced or depth-map shadow that can also be turned on or off, just like ambient occlusion isn't a hard shadow. Sorry if that's confusing. Do you have a render we could see?
 
Old 08-15-2012, 02:39 PM   #6
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So as I understand you can't separate that "lack of light" from final gather on a different render layer so I can adjust it in After Effects? Is there a quick way to adjust it in Maya or the only way to brighten it up is to set up more lights?


Last edited by Daryna : 08-15-2012 at 02:54 PM.
 
Old 08-15-2012, 04:29 PM   #7
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So this is the point in the conversation where I ask: "are you using linear workflow? Because if you aren't, you should."
 
Old 08-15-2012, 04:32 PM   #8
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In the meantime, I would actually recommend going about this in a slightly different way. Rather than using IBL to get your ambient light, why not just use an ambient occlusion pass? You can multiply it by a diffusematerialcolor pass and get a pretty decent ambient with a little more control. Just add your diffuse from the directional light, and you're good to go.
 
Old 08-15-2012, 08:37 PM   #9
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No, I wasn't using linear workflow. But thanks for letting me know, for sure I will try it. I guess that's what I kind of ended up doing is using the Diffusematerial color and ambient. But I like that greenish glow from IBL and I don't get highlights or " brighter parts" of the final gather as well. I guess it's just easier to fake the environment with standard lights.
 
Old 08-15-2012, 08:59 PM   #10
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http://mayahatesme.wordpress.com/20...inear-workflow/

See this link for a detailed description of what you're doing wrong. I don't mean to sound harsh, but working non-linearly is mathematically incorrect, and will cause problems like your interiors feeling weirdly dark. If working linearly doesn't fix the problem enough, a little extra fill from a point light should get you 99.9% of the way there.
 
Old 08-15-2012, 08:59 PM   #11
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