Light Fog (various approaches)

[abvfx]

Hey guys,

Last night i was playing with light fog. Getting it to work. Getting it to work faster etc.

So far i have been using the VEX Lit Fog shop, but it is a little slow, also i cant find a way for it to only be applied to one light. Even if i parent the atmosphere OBJ under the light i want it to be assigned to. Its seems to do it for all lights in the scene.

The second option is using the Z-Map Fog shop. Which sounds like the best option, but i cant get it to work right. I plug the shadow map generated from my light into it but it produces a square profile. So i made a simple map, black with a while circle in the center and it still doesn't work. But this method looks to be the most efficient (if only i could make it work)

The third is fluids. I haven't had much experience in the area. I have watched stephen's videos on SESI but need to go over them again to get a real grasp of the workflow and i also hear there is some material on the subject of light fog with fluids in the Fluids masterclass, it looks harder to control if you just want it to be n the path of the light. But it would be nice to hear some experiences.

thanks

-andrew

[brianburke]

Hi Andrew. I think the best way to do this is with a big low res volume primitive. You can create it easily with the Iso Surface or Iso Offset SOPs, and you can render it quickly by using a big Volume Step Size, a low Shading Quality, and by making sure its linked only to the light it needs to be lit by.

Good luck dude.

[rob]

I have seen environmental FOG done as mentioned above , in 3 layers/ close / mid / far using a density volume contained in a prim box. The skill comes in making the volume shader ! .

r

[jason_slab]

hey

the biggest problem we found with using a volume primitive is getting it to look good when you inside it, but this was with 9.5 maybe 10 is better..

we eventually settled on VEX lit fog, for our current project.

jason