Light cache suddenly extremely slow

[Bertjenkins]

Hi

I have a scene that was taking 6minutes a frame to render. The scene contained one rigged character in an environment.
I've simply imported another character (identical- ie duplicated) with the same skin texture map applied to it.
The render now takes 60 minutes to render in batch mode (DR). To render a single frame (thru VRB) takes around 6 minutes. I'm using IM and LC. PLus vray physical camera with DOF.

I've been using Distributed Rendering along three machines, and the other machines seem to slow down once the light cache kicks in.
However i've tried brute force and that's slow too. I don't really want to go down the brute force road as i have already rendered 6 shots this way and it's been working fine until this sudden slow down.

Does anyone have any initial thoughts on what might be causing the spike in render times?

I have been trying to trouble shoot this but at 1hr a frame it's taking me a while to go through all possible issues.

I thought it might be a random Maya texture or texture map but have checked through and they all seem to be the same settings as the previous render which took 6 mins.

Any help would be much appreciated

thanks

MAya 2012
Vray 2.25.01 for x64 build 22159

[Bertjenkins]

Hi Folks

Just an update. I've got the VRB render time down to under 4 minutes. I created another camera and matched the previous camera move and vray physical camera settings. Perhaps there was a bug in the previous camera which caused it to take longer (6 minutes). However now when i batch render it's an average of 50 minutes per frame.

The irradiance map is set to single frame and the light cache is single frame. Why should the batch render take so long? I can only assume it's something in the translation of the entire sequence to the batch renderer? But surely if its set to single frame it should only calculate for that frame?

This is completely frustrating. It's now taken three days out of a job which should have taken an afternoon. I've tried the various scripts (from creative crash) which created image sequences from the render view but they dont accept exrs. And when i use the vrb animation mode it slows right down to 50 mins again.

any ideas?

[vlado]

It would be best to get us a scene to vray@chaosgroup.com and our support guys should be able to help you find the problem.

In any case, it might be useful to check the 3ds Max Bitmap pager setting (make sure it's disabled) and also check the V-Ray dynamic memory limit (if there is displacement, hair or subdivision involved).

Best regards,
Vlado

[Bertjenkins]

Wow- thanks!!

It was the dynamic memory limit- I didn't even know it was part of the batch rendering process!
I guess the scene must have been close to the default memory peak and the adjustments to the scene pushed it over the Dynamic Memory limit.

Thanks so much! Renders back to 6- 7 minutes, I can sleep safely now...!