Disk lights when using directionality > 0.1, gets occluded

[I3ordo]

 Hi,
When using corona disk light with directionality above 0.45, the disk light despite being below the ceiling mesh and supposed to be clearly visible and not occluded by the ceiling mesh, gets occluded. So i always have to move the disk light 4-5cm away/below the ceiling so it does not get occluded by the ceiling mesh, but this results in floating lights.

It seems, as directionality  increased on the disk light, the disk light's ray origin point is moved on the opposite direction of rays casted and this results in the rays get blocked by the mesh despite the light's placeholder free from the occluding mesh.

I am asking for a corona light option that will prevent this behavior so that i can place light directly beneath the ceiling mesh and not care about floating spot lights or a suddenly darker scene with occluded spotlights.

That would be very practical , you know...

thanks for the consideration.

[TomG]

Can you provide a simple test scene? Not heard of this before - also, are you sure it is occluded, that is, it no longer casts light into the scene? Not just that it renders black (if so, is "prevent black appearance checked"? and if so, is this when viewed directly or when in refractions/reflections?)

[maru]

I am unable to reproduce this even with the light being very close to the surface and directionality set to 1.0.
If I am doing something wrong - please explain what. :)

[maru]

Actually, even if the light is slightly inside the box, it still casts light outside of it.

[I3ordo]

I am sorry but i have misinterpreted the problem , it was not the light rays that were blocked, it was the visibility of the "disk light" affected instead.

in the scene i have shared, The disk light is set to be "directly visible" and camera is 90 degrees perpendicular to the ground.

directionality= 0.45

and disk is clearly visible, no problem.

increase the directionality to 0.46 and the disk is still visible but a semi transparent and faded.

increase it more and the disk is semi transparent more
at directionality 0.5, and it s now black.

but if you modify the camera upwards towards the disk, it becomes visible and white again unless the directionality is below 0.50, it gets black no matter what angle you look at it if dir. is >0.50

So Both standard camera and corona camera has this behavior.

Maybe i should post this as a bug fix but i am not sure if this was physically more correct somehow...

[I3ordo]

Can you provide a simple test scene? Not heard of this before - also, are you sure it is occluded, that is, it no longer casts light into the scene? Not just that it renders black (if so, is "prevent black appearance checked"? and if so, is this when viewed directly or when in refractions/reflections?)

after reading your invaluable reply,  i tried "prevent black appearance" which was already checked and as it did not fix the black appearance, i went ahead and prepared the scene, but later that night  tried enabling back the "occlude other lights" option(which was a no-go for me as i always had to fake the position of the lights away from the ceiling and that option was causing shadows on the ceiling due to being away from the ceiling ) anyways,, they were not black anymore.

So overall i think your answer was the simplest solution to this problem.

[I3ordo]

so overall,  despite me misinterpreting the problem, not reading very carefully the responses, i got the solution i needed , I LOVE CORONA and thank you for creating and supporting it.

[maru]

Unfortunately the "prevent black" option doesn't work with "occlude" off. It's a known issue and it's logged in our tracker. Sorry for the confusion and the inconvenience, and hopefully you can continue with "occlude" enabled.

(Internal ID=573150459)

[TomG]

Glad we were able to help! As an aside, if ever this solution is unworkable, you can also do this - set the light to Direct Visibility disabled and give it the directionality, so it casts light into the scene but is not seen by the camera (may also need to disable visible in reflections / refractions too, depending on the scene). Then create some geometry to act as the visible light, use a Corona Light Material and set it to NOT emit light and be directly visible (and visible in reflections and refractions) with no directionality. Then you have the geometry visible to the camera without any directionality limitations, and an actual light to control illumination in the scene. Of course, the current solution is easiest in all cases where it works fine, since you don't then have a light and a light material to control and adjust :)