Animation with moving objects : Flicker, slow...

[Pixelo]

Hi,

Sorry if this sounds famililar, i have a common problem but can't seem to find the solution reading the numerous topics about it.
I want to make an animation with moving objects. After trying many settings, i always get flickering result and slow render times.

I've moved back to very simple settings to try to troubleshoot the issue.
Here are the screenshots with prepass and rendering settings.




With these settings, i get pretty low quality, with GI flickering (on the shadows mainly) and very long rendertimes.
IRMAP prepass is fast, 3 or 4 minutes per frame. Rendering is 30 to 60 minutes per frame.
When i render one frame, using "From File" and selecting the proper precalculated IRMAP, rendertime go down to 7 minutes.

Is anyone seing something wrong with my settings ?
Is it normal that using the IRMAP interpolation (2 frames for instance) is multiplying the rendertime by up to 8 times ?

Any help would be greatly appreciated as i've been struggling with this for many days now.
Thanks a lot,
Cheers,

[joconnell]

Could you upload a preview of your animation or your previous render so we can see what's animating in it?

[Pixelo]

thanks for your answer !
Yes, here is a 5 frame sequence.
For the moment, not much is moving except a tree with wind, but it's very slight.
But you can see the flickering (in the trees, in the shadows of the building).

[joconnell]

Hmm - is it all exterior stuff like this? I'd nearly be inclined to look at different GI methods if it's all outside such as brute force and light cache. Are you only using a primary bounce for your GI or have you got light cache baked into your IR map too?

[samuel_bubat]

With 30-60 minutes per frame you could optional try a bruteforce as primary.
Also your AA seems extremly high. (min 2 max 50)
I usually don´t use bigger values than min 2 max 5-6.
Regarding your GI settings. Render with Show samples enabled.
Those animation presets (depending on the light settings) often produces to much samples.
This is how it should not look like.
http://sorceress.netfrag.org/optix/b...problem_01.jpg
Rather like this
http://sorceress.netfrag.org/optix/b...problem_02.jpg
As less samples as possible in even areas where not much is happening.
As much samples as neccessary in areas where a lot is happening, like corners and things like that.
To get a result like this you might end up with min/maxrate settings like -6/-1 or -5/-2, but this is ok.
Another very important parameter is the Clr. Treshold. Again, just make some test to get the desired result.
Your Hsph subdiv. seems way to low (30). Try something like 80-100.
Also increase the the interpolation frames, 2 is nearly like rendering without a prepass. Try something like
4 or 5. In addition to that decrease your Interpolation samples. They take quite some additional time
as higher the interpolation frame value is.
I also wonder a bit why your renderings are so grainy while using an Irr. Map setup Do you use a dome light ?
If you have a slow moving camera and objects you can also do a frame blending in a compositing software afterwards.
This usually works well with Irr. Map flickering but not very well with Brute Force Grain.

here are some test I did in the past with similar settings.
http://sorceress.netfrag.org/optix/s_dynamic_GI.mov
http://sorceress.netfrag.org/optix/s_Ivy_madness.avi
http://sorceress.netfrag.org/optix/s_Ivy.avi

[Pixelo]

Hi,
And thanks for your answers.
My settings were really messed up after taking a bit from here and a bit from there, and modifying everything.
I've reverted back to vray defaults, and tried to keep it very simple with IRMAP as primary, and none as Secondary. Precalculating the IRMAP with Animation (Prepass) and then rendering.
It works pretty well, the result is much better with almost no flickering.
When doing my tests, i still have an issue : when ticking "use camera path", the prepass gets 2 times slower, and the render gets 6 to 8 times slower ! Do you think this is normal ? And my camera path isn't too long, only the camera moving 30 feet away in 100 frames...
Have a nice day

[joconnell]

Use camera path is designed for scenes with no moving objects at all, just a moving camera so you might be making an IRmap that fights with itself. I'd definitely try using brute force too, or failing that even give the vray ambient light a look? This post here might be useful! http://www.chaosgroup.com/forums/vbu...333#post415333

[Pixelo]

Hummm i'm not sure of this Joconnell...
See in the official Vray Help, the moving objects tutorial says "Use Camera Path" should be used with moving camera AND moving objects :
http://www.spot3d.com/vray/help/200R...ials_anim2.htm

[joconnell]

I'd be inclined to think that you should be getting far faster times than 50 minutes a frame, especially if you're only doing one bounce. Have you used the vray frame buffer much?

[Neilg]

Can you not pre-calc the GI and render the background, with trees not visible to camera but casting shadows, then render the trees as a seperate pass? If you've got cars & people, sphere fade, etc?
Doing a full frame every time for some leaves and small detail is a bit overkill.

[Pixelo]

Hi,
Thanks for your answers.
Yes i could tried the different techniques you suggested (brute force, pass with moving objects...). But being on a deadline i don't have time for further experimentations.
I've come to a solution with my single bounce IRMAP setting with two passes (precalc + rendering). Without "use camera path", result is pretty ok and time is acceptable so i'll go this way.
But when i have time i will try the other techniques suggested here.
Thanks,