Rendering with Pre-calculated GI slows down final rendering compared to per-frame GI?

V-Ray V-Ray for 3ds Max Issues
1

Hello,

I have a query, I’m rendering a “walkthough” animation, and I have pre-calculated the Light Cache and Irradiance Map. Now when I render the final animation, the rendering is taking a lot long than I anticipated.

As an example (cropped test) -

1 frame with pre-calculated GI = 217 secs

1 frame with per-frame GI = 87 secs.

I’ve pretty much gone with the ChaosGroup tutorial / setup, but is there something I’m missing?

The LC is rendered with 2000 sub divs, and the IM is set to “animation high”, every 10th frame (it’s a slow panning shot). Oh and it’s vray 2.4.

Does anyone have any ideas what might be the problem?

Thanks,
Dean

2

I remember having this problem a while back, don’t think I ever got to the bottom of it either.

3

Is Use Light Cache For Glossy Rays enabled when rendering in Single Frame Mode?
Would it be possible to send us the scene or part of it for investigation?

4

I´ve been struggling with this problem before as well.

For my part, the render times went considerably down when I changed interpolation for the final rendering from the default 20 (used for precalculating IRmap) down to 10-12.
You should also check my other thread here, some usful tips from Svetlozar there.

5

With a precalculated map, there are more samples in the map itself and V-Ray has to sift through more data to find the relevant GI samples so a certain slowdown can be expected. Reducing the number of interpolation samples can help, s ben_hamburg pointed out.

Best regards,
Vlado

6

Use light cache is ticked, as this speeds up my scene as there are a lot of glossy reflections.

I will send over the file, do you need maps, GI files, etc?

7

OK thanks ben_hamburg and Vlado, I will give this a try and see if it makes any difference.

Thanks,
Dean