Lights refraction visibility locked to camera visibility

[dgruwier]

Any word on adding a separate option for refraction visibility on lights? If this issue was a child, it would be going through puberty.

https://forums.chaos.com/forum/v-ray...ion-visibility
https://forums.chaos.com/forum/v-ray...ght-refraction
https://forums.chaos.com/forum/v-ray...t-to-invisible
https://forums.chaos.com/forum/v-ray...era-for-lights
https://forums.chaos.com/forum/v-ray...ves-refraction
https://forums.chaos.com/forum/v-ray...eflect-refract
https://forums.chaos.com/forum/v-ray...n-contribution


Just to add my own two cents, I see this functionality continue to cause headaches and confusion, especially in VFX where you nearly always want your lights to show up in refracted materials, without showing up in cameras. There are several workarounds, including overriding environment and using mesh lights, but there are certain cases where it's almost impossible to get around, and you end up having to mask the lights out in comp.

The way this works is unexpected, because it's unlike how visibility is handled in all other situations in vray, where "visible to camera" or "primary visibility" is not tied to refraction. It's sneaky enough that people sometimes don't even notice something is wrong with their render, or spend time troubleshooting it before realizing what's wrong. Especially a problem among students in my experience.

[fixeighted]

+1mil for this. Bizarre that it's not implemented already.

[dgruwier]

Some examples of how this feature has caused problems for me just recently:

• A shot that has glasses in them, lit with an on-set HDR of the environment. The HDR was more than enough to get some good refraction in the glasses without needing to do environment projection, but instead of using a dome light, I had to project the HDR on the inside of a sphere for the shot to work.
• A shot of a stream of clear liquid going out of a tap. Ended up actually using an object mask to comp out the background, that was awkward conversation with the comper. "So tell me again why you can't just render it properly?"
• A turntable set up that spit out slightly off renders for a few months until we figured out the refraction component was missing, because the scene had recently been modified to have a transparent background, by setting the HDR to invisible.
• A packshot of a transparent bottle. I had to use mesh lights for all of the lighting, because I needed them to show up in the bottle but obviously didn't want them showing up in the camera.

That last one was when I started contemplating writing a script to convert lights into mesh lights, so we can just use that whenever this comes up, but I had to just check first if there's ANY word on this, because it just seems like such a dumb solution.

[fixeighted]

The first time I encountered this was again a bottle shot over a decade ago, where I ended up having to use a self-illumnated card inside the liquid to
get what I needed. Far from ideal and certainly not realistic.
At the time I remember thinking I must be such an idiot for not knowing the proper method.
Turns out there never was one

[dgruwier]

Just helped a lookdev artist who had set up a reference lighting setup for lookdev, and had spent a while trying to figure out why the refraction shader in the vraymaterial was broken because it would show the floor but not not the lights.

[kosso_olli]

+1 for this!