Download

Can I exclude certain lit static or stationary objects from affecting volume light samples?

EDIT: I meant ‘Volumetric lightmap’ not ‘volume light samples’(4.18).

Hi guys, pretty much a self explanatory title.

I ask because sometimes we have to create area lights with bounce cards for fills for baking but we don’t want them affecting the volume light samples as that may give unwanted lighting results for moving objects. given these bounce cards can be overly bright sometimes.

Hi!

Lighting Channels?

Hi Makigirl, thanks for taking the time and your input.

Lighting channels work only on dynamic lights, I think perhaps the question is misunderstood. After a while of testing I couldn’t get it to work for the obvious reason that the area light that is being artificially created in unreal only produces bounced light to illuminate the scene, this naturally excludes control over what the actual physical light is affecting.

I was hoping a way to tell volume light samples or lightmass that whatever light and bounce light being generated from an X light source exclude it entirely from the volume samples created while still lighting the rest of the static scene as it should.

We don’t intend to expose any controls that can cause the surface lightmaps and volumetric lightmaps to diverge. They should be storing the same thing - baked lighting at a point in space or a point on a surface.

On the technical side, it’s very difficult and inefficient to track where light came from in a global illumination solver like Lightmass, which would be required for lighting channels or what you are requesting. Once light bounces a few times it’s just light, could have come from anywhere.

Thank you Daniel for taking the time to pitch in.

I will take your info into consideration.

In case it interests you, the reason why i asked is because of the following:

Usually we would be lighting certain environments with many bounce area lights to create the color pallete we need in the scene, sometimes these lights are small and directed at a certain object. In the offline renders we are able to tell the renderer to simply hide the light source and exclude them when we put the characters in. In unreal we have to fake the area light by creating bounce lights with boxes, while the bounce works very well in the scene unfortunately it also affects the path of where the character would be walking sometimes (Hence affecting the Volume samples there). We can always take more care in placing these lights (for instance further away) but this can potentially limit art direction in certain places where we need them closer to the ground or around corners.

Thanks again though.

Hi, why did you disable “Volumetric Scattering Intensity” in the Static Lights?

Old thread… but it’s because static lights bake to Volumetric Lightmaps, which are used to light the volumetric fog indirectly, compared to the Volumetric Scattering Intensity contributing to the voxelfield directly.

bad( because I didn’t need Volumetric Fog

You can scale the static light contribution to the exponential fog globally here: