Question regarding baking/faking light falloff gradients on textures using masks as light sources.

mwasilewski

Hey there,

Ok, so I have a quick question about any method that can replicate a light falloff on an asset in some sort of automatic / baked way.

Currently Im doing the falloff masks by hand to create this 'light glow' effect substance, it can be somewhat easily done in photoshop too, but due to how the UVs are laid out, it is not practical for this asset, nor future ones where the emissive mask may be more organically shaped.

First image is just the light source as a mask, intended for the emissive channel, then I created the falloff as in the lower image. 

Anyway to do this quickly as some kind of fake ..fake light bake? 

My colleague is experimenting in Houdini at the moment with some progress.  Any clues would be highly appreciated.

-M

Eric Chadwick

I've done this by using a path tracer, like V-Ray, and a baking tool like Bake To Texture in 3ds Max. Simply make the emissive a light-emitting material, and let the renderer cast the light onto the rest of the mesh. Then bake the lighting into the UV layout of the mesh.

Here's an example model
https://github.com/KhronosGroup/glTF-Sample-Models/tree/bc931eae7f8321fbed2e163447f2280b2d8f5050/2.0/StainedGlassLamp#khr_materials_variants
and the baked emissive being enabled/disabled:


And here's what one of the baked textures looks like:

poopipe

^ that's the way to get fancy results with minimal work.  Arnold can bake out whatever passes you like as well. 

if you want a quick hack substance is perfect for it - just mark the lightsource in a texture. add a distance node and apply a curve to it

if you need to work spatially then you can compare your light position to a position map - it's simple provided you don't want shadows

mwasilewski

Thank you guys for pointing me in the right direction, I forgot to mention Im a Maya user, and searching a bit further into Arnold as suggested, I've found the utility to do just as described above.

Many thanks!

-Mike