Area Shadow Problem

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Old 06 June 2009   #1
Cool Area Shadow Problem

Hi all! I have a little problem with shadows...
I put an AREA Shadow out from window, the result with Mental ray is a segmented shadow on the wall.
When I make it softer then I have a lot of noise. 2 problems! 2 damned problems...
Can someone help me? I think it's simple but I can't go out from this...

I attached a preview...
Attached Images
File Type: jpg Test_008.jpg (40.8 KB, 108 views)

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Last edited by neofg : 06 June 2009 at 02:55 PM.
Old 06 June 2009   #2
another image

That's another test...It's full of noise in the shadows...
Attached Images
File Type: jpg Test_022.jpg (59.1 KB, 110 views)

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Old 06 June 2009   #3
Are you using a regular Maya area light with depth map shadows? If so, increase the map size.
Jared Edwards
Course Director
Visual Development
Old 06 June 2009   #4
Unhappy A Mistery

Hi and Thanks.
No, It's an AREA LIGHT with Mental Ray's "Regular Shadow Map"
I tried to change aliasing settings in the MR tab, samples in the "shadow map" options but nothing...
If you look at the wall strange lines appear on it.
A mistery!

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...... O L D F U T U R E d i g i t a l ......

Last edited by neofg : 06 June 2009 at 08:09 AM.
Old 06 June 2009   #5
Switch to ray traced shadows, increase both shadow rays and high samples. Make sure you scale the area light itself to soften the shadows appropriately. If you're getting 'interference' like patterns, try increasing the adaptive sub sampling settings.
Old 06 June 2009   #6
i cannot see the problem, however if there are very tiny patterns (on that second image you posted, the very far left of the image) like what I think it is then it's the "bias" option. usually increasing this number gives less accurate shadows but decreases noise. a fine balance and tweaking is necessary.
Old 06 June 2009   #7
Question Mental ray shadows

Ok, but so I never solve the problem... I change the kind of shadow. I know how use the raytraced shadows...
But here I use the "mental ray area shadows". And all go wrong...

| my demoreel on cgtalk | |

...... O L D F U T U R E d i g i t a l ......
Old 06 June 2009   #8
Raytracing shadows is just a different method of calculation, it is irrelevant if you use area, point, spot, etc.

Try setting the High Samples to 24, High Sample Limit to 4 and Low Samples to 8; see how that looks.
Old 06 June 2009   #9
Unhappy look strange

Mmmmh...That look strange cbamber85. I tried your method with samples, but I have the same noise and a 33times more time spending. About Raytraced shadows is obvious that When I abilitate the "Mental ray shadow map overrides" the "raytraced shadows" don't work.
HamburgerTrain instead, the bias option make my shadows far from objects and work very very bad.
There must to be an option to decrease the noise with that options...

| my demoreel on cgtalk | |

...... O L D F U T U R E d i g i t a l ......
Old 06 June 2009   #10
How big is your area light compared the scene geometry? If it's massive you'll need more samples and more Shadow Rays. Post pictures of the changes as well.
Old 06 June 2009   #11
I "think" hes using a mR area light. Up the sampling in the area light's mr tab to reduce the noise
Old 06 June 2009   #12
The Solution

I solved the problem with an higher value of "resolution" in the "shadow map overrides".
From 1024 to 3-4000. Just a so simple value...
I hope this will be useful for someone in the future...
Thanks to all for your support...

| my demoreel on cgtalk | |

...... O L D F U T U R E d i g i t a l ......
Old 06 June 2009   #13
Your solution was the suggestion in the first response: "increase the map size."

Too bad it wasn't clear to you, it would have saved you a lot of time

Another thing...Make sure you choose a square pixel resolution for you shadow map to avoid any filtering issues. Example: 4096 or 2048.
Old 09 September 2009   #14
Im confused, you said you are using regular shadow maps MR, and now you increased the map size. Does that mean you switch to depth map?
Old 09 September 2009   #15
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