Baked Lighting Variation Between Static Meshes

[jonimake]

@DanielW;126123

On the BSP merging, there are some other parameter which can prevent it from merging, for example lightmap resolution.

The algorithm used by Lightmass which reduces build times for diffuse GI by 10x is called Irradiance Caching. As you consider each shading point for whether it needs the expensive lighting computations, you look at surrounding, already-lit shading points and see if you can interpolate from any of them. If not, you compute new lighting at the shading point, which will prevent neighboring points from doing the expensive work too.

So object processed on different threads start from different shading points, and therefore end up with different Irradiance caches and once we interpolate indirect lighting from the cache you get these seams. This is all half-way through Lightmass processing so it’s not easy to ask all the other workers for their finished Irradiance caches and merge them together.

Wouldn’t it be possible to program a system that has a shared irradiance cache across worker threads?