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Bachirk Bachirk avatar image
Bachirk Bachirk asked ·

Rendering Lightmaps in Maya 2017

How can we render to texture, Lightmaps in Arnold?

We were able to render to texture using aiAmbientOcclusion but how can we render out the light data and shadows? Is there any particular shader we can use, or other methods?

We used to be able to do that with Mental Ray similar to https://www.youtube.com/watch?v=DvmJZzhiiH8 and are looking for an alternative using Arnold.

Appreciate your help, thanks!

renderlightshaderrendertotexture
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Andy Fedak avatar image
Andy Fedak answered ·

This would be super useful to have built into Arnold for game engines like unity or unreal. You would use the lighting information and then do the specular response in the game engine.

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Ryoichiro Oka avatar image
Ryoichiro Oka answered ·

For anyone who came across this page -- @Bachirk Bachirk gave me a great starting point. I'm successfully creating lightmaps using Arnold, by baking two maps with different diffuse/specular ray depth in render settings, then blending them together.

  1. Bake a "light only" map with the depth set to 1;
  2. Bake a "light + GI" map with depth set to any number larger than 1 -- like 5 or 10;
  3. Blend them so that the "light only" map subtracts the "light + GI" map, to create a "GI only" map.

Now you have a "light only" map and a "GI only" map. In my application, I feed these two maps separately to my custom material and adjust their contribution respectively.

Note that depth set to 1 does bake some GI. It's been negligibly subtle for my application but may not be suitable with a strict "light only" requirement.

It took a while for me to figure out that ray depth sliders in render settings control GI intensity in Arnold. I hope this info helps you :)

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Bachirk Bachirk avatar image
Bachirk Bachirk answered ·

Thanks @Lee Griggs we are using that already but there is no direct way of isolating and rendering light information onto a texture. We are working around that by overriding the shader with plain white, so we can at least get the shadows and AO passes, but we are using indirect light colour.

There's more about it here where we used to bake Only Light + Only Global Illumination etc... then composite them and create a lightmap.

Can't find how we can achieve that with Arnold.

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Lee Griggs avatar image
Lee Griggs answered ·

Here you have: Arnold> Utilities> Render Selection to Texture

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