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Voxel Probe baking time


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When looking at my workflow, I am most constrained by the time it takes to bake voxel probes. Can anyone give any advice in why voxel probes take so long to bake for even a relatively small area with a not too small voxel size? For instance in my scene I want to bake a voxel with a resolution of 41 x 71 x 29, which is now taking over 1000+ minutes to calculate. It surely cannot be just a limitation of my hardware, is there something else at play here? 

 

I do not need to use any dynamic objects so was wondering if its possible to not bake the internal volume (if this can help save time), however I cannot see any setting to adjust for this. 

For reference my hardware is: 

GPU: Nvidia GTX Titan X (Maxwell)

CPU: Ryzen 7 3700x 

Ram: 32GB

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Hello, @Ben_93!

The parameters like "Number of Bounces" at "Bake Lighting" settings window and "Bake Internal Volume" with "Bake Quality" have the most impact on the voxel probes baking time. What exactly values are you using now?

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I do not need to use any dynamic objects so was wondering if its possible to not bake the internal volume (if this can help save time), however I cannot see any setting to adjust for this. 

There is no such a feature but even so you can bake the internal volume with "half" resolution which is should cut the estimated time by twice.

Thanks!

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Hi there! 

I am just using the default values, which is 4 bounces, the medium baking quality and only baking the internal volume at half resolution.

Do you think the slow baking time is a limitation with my hardware or anything? I am using voxel sizes of 0.3 smallest, which for interior scenes I dont think is so ideal, where I want to use a smaller voxel size for areas of details. However going smaller than 0.3 even for reasonably small areas would mean I need to wait at least 1000+ mins per bake even with these default values. 

Many thanks, 

 

Ben 

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However going smaller than 0.3 even for reasonably small areas would mean I need to wait at least 1000+ mins per bake even with these default values. 

Does it actually takes 16.5 hours or are you just reporting the value that the timer returns at the start? Truth be told it does not work very accurately and usually these numbers are much more then it's actually takes for baking.

May I ask you to take a snapshot with opened voxel probe parameters tab and also "bake lighting" window? We would like to see all the parameters you work with to be able advise you something more.

Thanks!

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Here are some screenshots of the voxel probe parameters and the bake lighting window. I used a similar resolution and voxel size to what I saw on Unigine's Global Illumination tutorial. 

 

image.thumb.png.e4c71de0e8f714b47de479f01bfa5797.png

image.png.413be3da7e393aa681b09d1f466af925.png

 

Here is a screenshot of a test in my scene

image.thumb.png.add3253ba4fdd386e5febd5928f3f5f5.png

I havent let it finish baking, but as you can see from the bake lighting window that its been running for 2 hours and is only 14% on the first bounce. 

image.png.03a428ed0b8419bfc1a832c323b979e9.png

 

It seems like a very long time for the finish bake as consequent bounces take longer and longer - is this time length for this sort of resolution normal?

 

Many thanks, 

 

Ben

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Hello, Ben!

Well looks like we see the reason now. Value of "Voxel Size" are extremely low, since it's equals to 2.5 cm such a long time for baking voxels are pretty expected result. Might be tutorial a bit confused you because the recording was speed up for a few times?

So, there is nothing wrong with your hardware as well is no issues with baking itself. Such a task with this size is very heavy and it cannot be calculated quickly anyways.

You can get better visuals (and much more detailed lighting) with lightmaps for interior scenes, it will take some time to set up but you will buy time in the long run. The internal volume can still be baked using voxels with a size of 30 cm for example.

Thanks!

 

 

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Thanks for the response. 

Yeah I understand such a low voxel size increases the bake time, but as I said I copied the voxel size from Unigine's video tutorial on global illumination (See below)

image.png.b3c20050a7cf231117c4a7354c893900.png

So normally a value of 0.025 is far too high for an exterior scene like this? A value of 0.3 might be enough?

Im eager to try out lightmapping using the GPU lightmapping tool, but every time I try I tend to get weird artifacts.

 

Many thanks, 

 

Ben

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Hello, @Ben_93!

You see it's hard to tell what exactly value will suit your needs - this numbers must be determined empirically by trying different approaches. If visuals with 0.3 are acceptable for you than go for it.

You can increase the "Voxel Size" by ten times in order to quickly evaluate the result and then bake the final scene on small values like 0.025 leaving your workplace overnight :)

Thanks!

 

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  • 2 weeks later...

Is it possible that Voxel Probes get GPU support in the future, or perhaps delegating to a computer cluster?

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@silent Unreal has a system they call 'swarm'. It is capable of delegating global illumination computations to other computers running unreal on lan. That way a game studio doesn't have to have a compute server, they can just have swarm running on each computer and whenever someone needs a light bake, computers in the entire  studio can help and it is done quickly. 

I find voxel baking times prohibitively slow, even on GPU and 'draft' setting.

Edited by flappybird
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