Shadow Flicker in 9.5

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  10 October 2005
Shadow Flicker in 9.5

I am working on a large arch-vis animation in 9.5. I started rendering the first path last night and when I check the results this morning, I was shocked to find that my shadows semm to be flickering. This has never happened before on my animations. The lighting setup is a soft shadow light dome, 1 ambient light, and a hard shadow sun. I am using a mixed network to render; which I have found caused problems for my quicktime textures (animated image mapped people would flicker). By using an image sequence I avoided the flickering people. However now my shadows are flickering the same way the people use to. Thew only thing I can think of is a difference from PPC chips to AMD chips. Has anything changed in the rendring engine that would cause this?

Here is a clip (15.2 MB) of what is happening. It is most noticable in the left center of the clip, in the light dryvit portions of the buildings. Ignore the crawling in the video, it isn't there in the full res.
  10 October 2005
I have a simmilar problem with Release R9.5.

I was renderin a part of a new animation with a slow camera move.
I achieved flickers in the render files.

No area-shadows has been used.
Just normal Light-dome with soft shadows.

First time having this problem - First time rendering with R 9.5

Here is a video file as ANIMATION - PREVIEW !!!

Hope anyone can help!
my 3D work / contact me...
  10 October 2005
Fred - what version MOV is that? i cant view it

Pegasus - that flickering looks either like your animation gi settings aren't high enough or set to the wrong solution for anims, or maybe it's a plain old video compression issue.

if you used no gi and gi mode was switched off, then i'd plump for the latter.
  10 October 2005
I used no radiosity and no AO.
Just a dome of lights for the smooth lightning.

I renderd a psd.sequence als image sequence and made a .mov file using AfterEffects.
So the flickering was befor compression to video.

Ist is possible that the lights have to be adjusted after converting fom R 9.1 to R 9.5?

By the way I am using a multi processor (2x) intel system. Could this affect the render lighting?


Originally Posted by STRAT: Fred - what version MOV is that? i cant view it

Pegasus - that flickering looks either like your animation gi settings aren't high enough or set to the wrong solution for anims, or maybe it's a plain old video compression issue.

if you used no gi and gi mode was switched off, then i'd plump for the latter.
my 3D work / contact me...

Last edited by Pegasus : 10 October 2005 at 12:23 PM.
  10 October 2005
have you tried caching the shadow maps?
  10 October 2005
I am using H.264 (QT 7) for compression. But looking at the files, it is deffinately something that is changing based on what machine rendered it. I think I am just going to have to rerender the offending frames. Is anyone else rendering on a mixed network?
  10 October 2005
if you jump thru the animation it does not show every frame different lighting but more like 4 frames dark 4frames lighter....etc so my guess is that it comes fromthe light dome's shadowmap resolution, render 50 frames with superhigh shadowmap settings and check what happens? maybe it will give you a clue where it comes from
  10 October 2005
'Dusi, thanks for looking, but it isn't the shadow map. the grouping of light and dark comes from the machines the frames were rendered on. Net assigns clusters of frames to machines. The quick flashing at the end is Net redistributing the last frames to finish the animation. I have used this lighting setup before, and never ran into this problem. The only similar problem was flashing quicktime movies (5.4 MB) (once again caused by a mix of pc and macs).

Srek, Is there now a difference in the way shadows are calculated in 9.5? One that would differ from PPC to Intel/AMD? I know it isn't recomended for particles, but now is it not recomended at all?
  10 October 2005
this problem is killing me right now.

I'm trying to knock out a job so i can get out of here and go home - but I keep coming up with flickering soft shadows! It's gonna be a long night I'm afraid.

Single light source (area light) with soft shadows.

I'm rendering with 2 dual-core 2.8 Pentium stations and one single core 1.8 AMD station using NET render.

I'm about to try a test with just one machine to see if the flicker shows up.

Stay tuned...
  10 October 2005
Some flickering is inherent to soft shadows when objects move through them as they're basically bitmaps. In order to minimize the normal type you will need to up the resolution and raise the sampling radius. Another flickering/artifact i've found has come when a shadow cache is incorrectly not updating but geometry is moving (i.e. the geo moves into it's own shadow!), at times it may be better to not have/use a shadow cache. Alternatively try using area shadows. if they take too long reduce the number of samples and/or the accuracy till it's acceptable, and a final option is to render to hard shadows, but use multipass and blur the hard shadows in post a little.
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Last edited by mdme_sadie : 10 October 2005 at 06:46 AM.
  10 October 2005
I ended up increasing the shadow map size as well as the sample radius. I usually don't have this problem, but this scene is on a very large scale with small objects - so it makes sense that the shadow map needed more resolution.
  10 October 2005
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