Multiple self illimination light select AOVS

[thomas_drenth]

Hi Everyone!

Currently I'm working on a project where I have to animate 4 different self illuminating objects turning on and off. Usually with any lights turning on and off I animate this in post using the lightmix passes to get more flexibility.
Is there a way to set up lightselect passes for the different self illuminating objects with GI and reflections as a light select passes to composite in post? I could animate it in 3D ofcourse but I wonder if it is possible to set this up for the composite.
I assume it could be done with Light Path Expressions but I am unfamiliar with this to set it up properly. If anyone has an idea on this please let me know, and thank you in advance!

[vladimir_krastev]

Hi thanks for posting. I don't understand why would you need to use Light Path Expressions? You can add a light select for each light and then use them in post to animate the intensity.

[thomas_drenth]

Thank you for replying! The thing is they aren't lights, they are objects using VrayLightmtl. My apologies if I didn't make that clear.

[will_will]

Why don't use mesh light , they can join light mix calcutation, separately .

[hermit.crab]

Sorry to say, there's an active issue with VRayLightMtls with active DI - they cannot be extracted through LPE (internal bug-tracker id: VMAX-11625). An alternative seems to replace the VRayLightMtl shaded objects with VRayMeshLight ones.

[thomas_drenth]

Thank you for the replies. That's too bad. I shaded the material with a falloff to get some color difference in the objects, hence why I am not using the mesh lights for this.

[hermit.crab]

Thank you for the replies. That's too bad. I shaded the material with a falloff to get some color difference in the objects, hence why I am not using the mesh lights for this.

Is the result not satisfying with a textured VRayMeshLight?

[thomas_drenth]

Somehow the VrayMeshLight doesn't show the falloff correctly. In what way could I shade or texture a VrayMeshLight? The objects are spheres that need to be viewed from every angle so a uv-ed texture won't work well for this.

[Joelaff]

Thinking out loud here…

Depending on render times perhaps render one beauty pass with all lights on. Then render four individual passes with the only light on in each pass being one of the lights in question. Then subtract these in post and animate the subtraction. ?? Basically a hand made light select.

[hermit.crab]

Somehow the VrayMeshLight doesn't show the falloff correctly. In what way could I shade or texture a VrayMeshLight? The objects are spheres that need to be viewed from every angle so a uv-ed texture won't work well for this.

If you do the UVs prior to converting the object to a VRayMeshLight -they should be retained (just tested this and it works). Basically, clone your already existing object, convert it to a mesh light and plug the texture in the map slot. Also, results seam to be identical when comparing a VRayLightMtl vs VRayMeshLight (identical multiplier, texture and DI active).

[thomas_drenth]

Thinking out loud here…

Depending on render times perhaps render one beauty pass with all lights on. Then render four individual passes with the only light on in each pass being one of the lights in question. Then subtract these in post and animate the subtraction. ?? Basically a hand made light select.

That's not a bad idea! I was thinking of doing something like this if I couldn't find an alternative. For now I set up a glossy glass material with a light inside that gives me the desired result and control I'm looking for. Thanks for the idea!

If you do the UVs prior to converting the object to a VRayMeshLight -they should be retained (just tested this and it works). Basically, clone your already existing object, convert it to a mesh light and plug the texture in the map slot. Also, results seam to be identical when comparing a VRayLightMtl vs VRayMeshLight (identical multiplier, texture and DI active).

That's good to know for future reference. For now I was able to get a desired result as mentioned above. Thank you for your help and knowledge.