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# 1 15-10-2002 , 07:29 PM
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Lights have a mind of their own?

I've been working on an animation, for anyone who has the Maya fundamentals book, i'm rendering my completed spooky house scene. Anyhow, i'm rendering out to tiff, there's 600 frames but having probs with lights. A few times during the animation, the lights just dim to where the scene is barely viewable then after a few frames they are back to normal levels. I have no idea why this is happening, anyone else? I'm attaching two consecutive frames.

I've also noticed the file sizes of the dimmed images are about 85% less than the the images that are rendered correctly. I won't be rendering this scene again, it's taken 16 hours with 2 processors but i'd really appreciate any help for future projects.

# 2 15-10-2002 , 07:30 PM
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Here's the correct lighting of the previous frame.

# 3 15-10-2002 , 07:43 PM
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Why don´t you try running a Render Diagnostics (Render Menu)? Might point out some clues.

Another thing is Maya uses a default auto-exposure feature that has to be turned off, It causes light, shadows, or even frame flickering to appear in animations. (Since Maya tries to set the exposure to all frames individually.)

# 4 15-10-2002 , 07:50 PM
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By the way, as a good rule of thumb, If you´re going to render large animations, try doing it by layers and then compositing. That way you´ll avoid yourself situations like this one.

And as an added bonus you´ll get to customize even better the look of your animation.

This thread has more info on rendering by layers.

# 5 15-10-2002 , 07:57 PM
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Thanks for the reply. Render diagnostics didn't show anything up other than recommendations to lower the tesselation on some parts of the scene. As for auto exposure. I've taken a look and the only time i see auto expousure is when you use Maya's default node, shaderGlow1. I am using a glow, though it's not visible in the frames i posted but i used a light and opticalFX and i don't see any options stating auto expousure. Only where i mentioned above?

# 6 15-10-2002 , 08:01 PM
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Ok, I see.

And what is the behaviour of the frames? Do they flicker? Did you by any chance keyframe those lights? (with Auto Key on) Check for that also.

Might be power shortage also on that zone? user added image

# 7 15-10-2002 , 08:13 PM
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The frames don't flicker at all. The animation runs ok, then all of a sudden the lights dim instantly, as in one frame to the next, this may last for 7 or 8 frames then all of a sudden they're back to normal. There's a few places where it also dims for only 1 frame. I looked in the graph editor for all lights and i see no keyframes in there, i guess that would be the place to look. The first thing i though was i must have animated the intensity's accidentilly but i don't see any evidence of this. I adjusted the intensities to my liking but didn't animate them.

Wow, this is a frustrating problem. what did you mean by

"Might be power shortage also on that zone?"

Thanks again for your help. Once the render is complete i'll make the movie available to show exactly what's happening.

# 8 15-10-2002 , 09:05 PM
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Now this is a tricky one. Hmm, You could also try exporting the geometry and animation curves, and redo the lighting setup. Might as well start fresh.

The power shortage thing was intended as a joke.

# 9 15-10-2002 , 09:17 PM
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ahh, i was too freaked at the time to notice the joke user added image I already re-did the lights. The original scene, before i added paint effects ans some particles did the same thing. I deleted the lights and started afresh and now i see the same problem. I'm totally clueless.

Could it be hardware related? I have no idea. I'm rendering with both CPU's and i'm continuing to use the computer. I noticed for the most part Maya is using around 55% of both processors but it does rise for a few secs every frame to !00%, probably lights, paint effects and/or particles. Is there any chance if i'm using the computer during these periods it can effect the render? I'm clutching at straws here user added image

# 10 15-10-2002 , 09:39 PM
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Whoa, now that´s freaky ... might as well consider sending the *MB file to one of those maya´s gurus around here, because I´m clueless already.

<-- puzzled ... user added image

# 11 15-10-2002 , 09:42 PM
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Anyone offering to take it and have a look?user added image

The scene file is here anyway
https://www.freewebs.com/revert/houseComplete.zip

Ok i'm attaching the actual animation now. This is the first time i've viewed as an animation and yes, it does seem to flicker though for the last frames it's just almost black. It's heavily compressed, using divX 5.02, it's 2.2mb's in size if anyone wants to look and offer advice. I created clouds with the painting tools to fake fog and also use a little envirenmental fog. The fog looks really odd though, like it's animated? I'll have to look again, i guess the 3d paint clouds might be anmated y default like some of the trees/grasses.

https://www.freewebs.com/revert/house1.zip

Just one more thing to add. Looking at my rendered images that are lit incorrectly, if i do a render scene within Maya of the same frame number, they come out correctly. Strange.


Last edited by mrmacca; 15-10-2002 at 10:29 PM.
# 12 16-10-2002 , 03:48 AM
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It´s a pity that the animation is flickering like that at the end, because I found it quite entertaining (Always great to see something move right?) As per the *MB file, it taxed my computer (only way of watching it was by Bounding Box only) So I sincerely don´t know what to do with this one.

I thought the problem might be the fog or the fact that the camera passes just through the moonglow. Somehow I think it might be over there the problem. When you saw the autoexposure option did you actually turn it off?

# 13 16-10-2002 , 04:02 AM
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I know the scene file is heavy, not so bad with hardware texturing turned off. Anyhow, no i didn't turn auto exposure off, i'm not going to re-render that animation, it was just a little learning project. I will turn it off if i'm in the same situation in the future and see if that helps.

I did think about the fog causing the problem. I could remove it and re-render it just to see if that is the problem, i'd like to find out. Then again it could be auto-exposure so that would need another render just for elimination. user added image I think i'll keep your ideas in mind for my next project and see if they help. I'm lucky im getting the opportunity to spend a little time with Maya, i don't want to be sitting around too much waiting on 16 hour renders!

Thanks for all your advice. user added image

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