Occlude other lights

[dj_buckley]

I'm currently getting a really strange effect, where it seems like my 'Occlude other lights' checkbox is working the wrong way round.

If I leave it unticked, i'm getting shadow from what appears to be the light cone, if I tick it, the light works as expected.

See screenshots - the lights are 3 disc lights next to each other with an IES file

[dj_buckley]

Just to add to this, this is how it looks from the correct camera angle.  The weird shadow doesn't look as bad but it's not right still.  But then if I tick 'Occlude' in the camera view, the light looks correct on the floor but now the lights themselves cast a shadow on the soffit

[dj_buckley]

I'm gonna take a guess that the scenes corrupt, will try and merge into a new scene without those lights

[dj_buckley]

After some more testing it seems like a bug when using IES and/or dark materials.  Will do more test in the morning and report back.

[dj_buckley]

Ok so there seems to be a bug with Corona lights and darker materials and reflection.  See the screenshots attached.

I've only changed one setting between each image.  A-C are with a darker override material set to 30,30,30 RGB, D-F are exactly the same but with a lighter override material 150,150,150 RGB.

The disc lights are all instances with an IES profile attached.

I've highlighted in bold the changed setting in each image.

Image A - Dark Material, Reflection Level 0, Glossiness 0.5, Lights 'Visible to Reflection' Unticked

Image B - Dark Material, Reflection Level 1, Glossiness 0.5, Lights ' Visible to Reflection' Unticked

Image C - Dark Matertial, Reflection Level 1, Glossiness 0.5, Lights ' Visible to Reflection' Ticked

As I say D E F correspond with A B C but with the diffuse colour changed to 150,150,150 RGB.

If anyone can shed any light on what's happening in Image B, I'd be hugely greatful.

It's worth noting that if I set it up as per image B and then tick 'Occlude Other Lights' the problem disappears, but then the disc lights themselves cast shadows onto the soffit which you can't see in these tests.

[pokoy]

I don't think the occlude option has anything to do with it. From your tests, it looks like reflection of the lights is the culprit here, or am I missing something? This would then fall under the known limitations when using a light with 'visible to reflections' checked off and the effect that has on glossy materials. This has been reported a few times and is a limitation of the current light transport integration AFAIK. It's gotten a bit worse over the last couple versions, it wasn't that noticeable with former Corona versions.

I guess exactly the same thing happens with the lighter material value only that you can't see it because the direct light blows out all values towards white and you don't see the reflections anymore, they're too subtle. I guess both material colors would show a similar effect if you look at a reflection pass.

[dj_buckley]

That's what I'm thinking.  However, that's terrible imo.  It makes the lights unusable for me.  What makes it even more interesting, if I hide the soffit geometry, the issue disappears.  So it almost feels like the light is casting light onto the floor, this light bounces back up to the soffit, and then on the bounce back down its casting a shadow from the IES light if that makes sense.  Almost as if the secondary bounces are treating the light/light cone as geometry

[dj_buckley]

Demonstrated here.  Same settings as Image B, but with the soffit geometry hidden.  Problem dissapears

[dj_buckley]

And one more, this has the soffit hidden, but the geometry light fixtures (2.5mm above the IES light) visible.  Problem reappears.

[dj_buckley]

I guess my only solution is to get rid of the non-emitting light material, and place the IES inside the light fixture and enable visible in reflections

[sprayer]

Could this be bug with scale and size of light source? I remember what was similar bug to me in past, it seams your system scale is inch and showing as mm so it maybe that case with light scaling.

[dj_buckley]

My solution isn't a solution either.  If I use an IES profile and make it visible to reflection, you don't actually get the disc shape.  So there's nothing actually visible in reflection when using an IES profile.  You still need to non-emitting light material applied to geometry to get the shape

[dj_buckley]

Could this be bug with scale and size of light source? I remember what was similar bug to me in past, it seams your system scale is inch and showing as mm so it maybe that case with light scaling.

Correct the system units in this scene are inches but display units are set to mm.  However, I've tested and can replicate in a scene setup correctly as shown in attachment.

[TomG]

Using an IES has the same effects as using directionality (as that is what an IES profile is, constraining the light intensity in certain directions), which leads to the same known issue of lights appearing black in reflections (because it's a reflection from outside the cone that light rays are cast in), rather like the issue in https://forum.corona-renderer.com/index.php?topic=23208.msg141676#msg141676. If this is the issue, should be possible to have one light source casting rays and invisible, and one not casting rays but acting as the thing to see in reflections etc. (or an object, rather than a light source).

[dj_buckley]

Tom, thats the exact problem, if I make the IES light invisible to reflection then I get the shadow/reflection issue in Image B.  Having a non-emitting light fixture for reflections makes no difference, I still get that weird shadow just by turning off 'Visible to Reflection' on the light casting light