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View Full Version : Compositing Buffer Export Ambient Occlusion produces weird results?



egearbox
03-31-2014, 07:40 PM
I'm taking a stab at multi-pass rendering for the first time, and I've run into a snag with the built-in Ambient Occlusion buffer in the Compositing Buffer Export. When I render a frame sequence out to disk, the first frame looks fine, but subsequent frames look awful - they're mostly black with blotches of illumination jumping around from frame to frame. (Samples attached).


121111121112121113


Anybody seen this before? Is it a setting? A bug? Sunspots? Gremlins?

Here's the scene if anyone wants to look at it...

121114


Thanks....

egearbox
04-01-2014, 04:27 PM
Some additional information: When this problem manifests, the first frame takes 2 minutes to render, the remaining (bad) frames only take about 45 seconds. So something's getting missed.

Additionally, if I turn Radiosity Caching on, the problem disappears but each frame then takes 8 minutes to render (arrrrrgh!)

spherical
04-02-2014, 03:39 PM
I took a look at it. Interesting that F9s of the same frames don't produce dark OC passes in frames past 0. Turning off Interpolated fixes it on F10s.

egearbox
04-02-2014, 04:44 PM
That is interesting! I hope LW can find the underlying issue (I reported it to tech support) but in the meantime I'll try some tests with Interpolated off. (Was going to try some more fiddling with settings yesterday but there are only so many hours in the day.)

spherical
04-02-2014, 05:06 PM
32.5 for me so far. It'll be 40+ by the time I call it a day.

egearbox
04-02-2014, 05:47 PM
32.5 for me so far. It'll be 40+ by the time I call it a day.

LOL - you're a tougher cookie than me.

spherical
04-02-2014, 08:17 PM
Gotta work up to it. Personal record when working for Penske Racing is 93 hours. Have to step up and do the impossible. Good story that I really need to get on my blog but, if I hadn't done that stint and kept going while the rest of the crew rotated out in stages to get their batteries charged, we most likely wouldn't have won. Once you have that capability, it's best to keep your hand in. When I need it, it's there for me to tap. Everyone isn't like me, of course, but there always are possibilities.

MSherak
04-03-2014, 02:19 PM
I'm taking a stab at multi-pass rendering for the first time, and I've run into a snag with the built-in Ambient Occlusion buffer in the Compositing Buffer Export. When I render a frame sequence out to disk, the first frame looks fine, but subsequent frames look awful - they're mostly black with blotches of illumination jumping around from frame to frame. (Samples attached).


121111121112121113


Anybody seen this before? Is it a setting? A bug? Sunspots? Gremlins?

Here's the scene if anyone wants to look at it...

121114


Thanks....


Download and install DPKit/DPFilter and load this scene. You should get your render speed back. Adjusted GI with no caching. Better AA and AO in the alpha.. All for under 1m30s per frame. I placed the AO in the alpha since you where not using that channel and it makes it easier to see what its doing. If compositing in say AE just extract the alpha as a layer sequence. Oh and no composite buffer to deal with.

-enjoy

egearbox
04-04-2014, 04:31 PM
Download and install DPKit/DPFilter and load this scene.

Thanks! Yes, I have the DP Kit stuff installed, but I kind of thought the internal LW stuff should work. :( It's a bummer that it doesn't seem to. And turning off Interpolation kills the render times.

egearbox
04-04-2014, 04:40 PM
Forgot to add that's a neat trick putting the Occlusion in the Alpha layer. Kind of a two-for-one render solution!

spherical
04-04-2014, 10:46 PM
Thanks! Yes, I have the DP Kit stuff installed, but I kind of thought the internal LW stuff should work. :( It's a bummer that it doesn't seem to. And turning off Interpolation kills the render times.

First thing I'd to to assist the render times, so you can apply other methods to get what you want and do it at a similar time per frame, is to relax the Adaptive Sampling Threshold from 0.01 to 0.08 or even 0.1. I see minimal change in the render but significant change in time. That this is an animation, small AA artifacts in each frame become less noticeable, due to the FPS. Doing that lowered the render time by a factor of 2.7. Speed can also be gained by setting the GI Multiplier to 50% and adjusting the Min/Max Pixel Spacing, if necessary. Also try Bake Radiosity Scene to create the cache file prior to the F10.

MarcusM
04-05-2014, 02:53 AM
Try render occlusion as shading buffer.