Corona Sun + Sphere = Reflect bug ?

[Herve-Marmillot]

Hi there,

I'm currently having trouble with some basic reflections with Max 2018 + Corona 1.7 :

I use a sphere with a CoronaLightMtl and an environnement bitmap in the textmap for the reflect of my scene, and a simple CoronaSun to enlight all of this.
I placed a simple sphere with a glossy material to test show the problem : in the reflects the sun is dark and in a global scene it makes dark areas in glossy materials.



See attached jpgs to see details of mats and scene.

Has anyone a solution for this ?

Thanks a lot,

Herve

[TomG]

The explanation is on this page:
https://coronarenderer.freshdesk.com/support/solutions/articles/5000516180-known-bugs-and-limitations

The part that reads :
"Black highlights":
-Black reflection of sunlight may be visible on materials with glossiness lower than 1, if sunlight is passing through a Corona Light material with "emit light" option disabled


To avoid this in this case, you could just place the CoronaLight material in the Environment slot (or add it to the Reflections override) instead of using geometry to place the environment on.

[Herve-Marmillot]

The explanation is on this page:
https://coronarenderer.freshdesk.com/support/solutions/articles/5000516180-known-bugs-and-limitations

The part that reads :
"Black highlights":
-Black reflection of sunlight may be visible on materials with glossiness lower than 1, if sunlight is passing through a Corona Light material with "emit light" option disabled


To avoid this in this case, you could just place the CoronaLight material in the Environment slot (or add it to the Reflections override) instead of using geometry to place the environment on.

Thanks TomG, yes it resolves the problem but when I place the CoronaLightMtl in the Env. slot there is no mapping and the environnement isn't enlighted, so it doesn't appears like a real sky... 


Maybe someone has a better solution ?

[maru]

The idea with big sphere surrounding your scene does not really make sense.
You should plug your image/hdri into direct visibility and reflections override in scene setup tab (possibly refractions override too). Then adjust the intensity of your texture using the 3ds Max "output" in the bitmap's preferences.

[TomG]

For the Env slot, don't drop in the Light Material, just the Corona Bitmap straight into the Max Environment slot (sorry, had my C4D thinking cap on there, which has a bit of a different approach to adding an HDRI!)

Lots of examples on the YouTube tutorial channel, e.g. https://www.youtube.com/watch?v=QAV4Wedy8u4