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

[notamondayfan]

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

[Macker]

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

[svetlozar.draganov]

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?

[ben_hamburg]

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.

[vlado]

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

[notamondayfan]

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?

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?

[notamondayfan]

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

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

Thanks,
Dean