Chaos Corona for 3ds Max > [Max] General Discussion

Animation flickering with HD cache

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fobus:
Hi guys.

I'm very interested in new to me Corona renderer. I'm doing a little clip of future interior with animated things like robots and furniture. Usually we're using V-Ray for our works but for this clip with lots of animation (usually we're have only people and cars moving in exterior scenes or just people in interiors). I found that Corona is great for animation and started to do animation with it.

During the previsualization I found a little strange thing with flickering the secondary GI named "HD cache" (it's not about the noise, but flickering of whole lighting of secondary GI). As you can see in attached file default settings (top video) of Corona flickering is quite pronounced. Of course I'm started to find the problem. And it was the parameter "Refl glossiness threshold". In default settings it has a value of 0.9. With this value it produces a cleaner image in blurry reflections, but in expense of flickering as I found. I don't know if it's right, but in my tests it is. Then I set "Refl glossiness threshold" to value 0.08 and render animation preview with it. As you can see at bottom video the flickering is much less pronounced in movie then with "Refl glossiness threshold" 0.9, but still there.

May be I'm doing something wrong and you know the way to turn this flickering down?

Ondra:
reflection glossiness threshod disables HD cache for too specular objects. It seems you have probably disabled it for most of the scene in the second case. You can confirm by comparing the HD success rate % in the statistics in VFB between the two renders. The current best solution is to save and reuse the cache (save/load secondary GI option)

fobus:

--- Quote from: Keymaster on 2013-11-15, 12:11:52 ---The current best solution is to save and reuse the cache (save/load secondary GI option)

--- End quote ---

Yea. This seem to work with  fly-through animation without moving elements, but with our animation full of moving subjects and turning lights on and off it is unusable as I see. I've tryed to save HD cache for first frame and reuse it in animation but it feels like all the lights bounces has gone for secondary GI.

In attachment you can see frame with saved HD cache (on left) and with computed during render (on right).

Ludvik Koutny:
Keymaster probably forgot to mention saving HDcache only works in scenes with static lights and objects.

I would try reverting HDcache settings back to their defaults, and then increasing position sensitivity to 100, and see if that helps.

HDcache at the moment is unfortunately not flickerfree. So either you have to use Path Tracing as secondary GI, which will increase your rendertimes, or try increasing positional sensitivity of HDcache, or just wait until flickrefree cached secondary solution is implemented. It is very high on priority list.

fobus:
Thank You for possible solution. I'll try to check it and reply soon.

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