Occlude other lights

[TomG]

The scene itself would be helpful, as it often is in these cases - the private uploader can be used https://corona-renderer.com/upload

(Edit, you can strip it down to just enough to show the effect, if you want to reduce upload times / not share the whole thing for confidentiality reasons even though it won't go any further than the Corona team / make life easier for support and developers ;) )

[dj_buckley]

Scene attached, really simplified.  Easily to replicate.

Keep the material quite dark, adjust the reflection level gradually while in interactive to see the effect.

Then play with the 'visible to reflection' checkbox to see it again.

You'll need to replace the environment light as I've made this public I had to strip out PG's HDRI but I used one of the dusk ones.

[TomG]

Yes, looks like that light transport limitation regarding lights in glossy reflections. You could try enable visible in reflections for the light sources, that removes the "shadows" from them. In this test scene at least, you could also change the cylinder that is the light fixture, by using a RaySwitch with nothing in the Reflection Override, too, as it's the combination of the light, the object behind it that it is occluding, and the glossy reflection that causes the issue (if you hide the cylinders, the "shadows" - which are reflections actually, if they watch how they move when the camera moves - disappear).

[dj_buckley]

Hi Tom

Thanks for confirming.  As far as I can tell you simply have to have the light visible in reflections to not get that 'shadow' it's less noticeable on bright scenes to the point it's hardly visible, but it's still there and really messes with how materials appear too.

As I say, it's not a problem having the light visible in reflections when using an IES as you won't actually see the disc shape anyway.  However if i was just using the disc and didn't want it visible in reflections then I'd need to do that rayswitch thing to everything 'behind' the light source until the problem disappeared, or simply have the disc visible to reflect, and get rid of the geometry with light material and use the light source in it's place.  Not sure what method I'd use for anything not a standard shape :)

[TomG]

Yes, definitely something we want to revisit at some point, even if there is a workaround in this case that is at least "ok". Thanks for the report, and the scene to take a look at exactly what is happening!