Black edge and question about reflection

[RobertRay]

HI all,

I have made a reflection catcher and it's almost done. I have a few questions as I do not understand some settings.

But first, why is there a black edge? (see image, on the shadow side, the top and right edge have a distinct black edge.)

Second,
The cube is 1 cubic meter, why does the Dim distance need to be at least 2.2 m to have a full reflection? (in the image, the dim distance is 1.5 m).
The Dim fall-off is set to 1 in the image, but I still have a hard ending reflection. It does add a white glow near the end. When setting the "Affect channels" to something other than 'all-channels' the dim fall-off is correct but the color in the reflection is gone.

All materials are standard V-ray materials.

[RobertRay]

turning sRGB off, gives this result.

Scene has 2 lights, turning one off, only moves the black lines to other edges.

sRGB off and adjusting the v-ray camera settings (iso, shutterspeed, etc.) shows that even with sRGB off the black edges are still there.

[boyan]

Hey, Robert,

Thank you for the feedback. I've added as attached file my scene file for your test. please check it. About the black line, I will need to check the scene file, if you can share with me. Dim_Distance.zip



Cheers,

[RobertRay]

Hi Boyan, thanks for the file.

As soon as I set the shader to shadowcatcher, dim distance doesn't work anymore when 'all channels' are selected. If I set it to opacity it is like your scene. What can be done about this?

[boyan]

Hey,

Within V-Ray Next you have ability to create the shadow catcher by using Shadow Catcher option or V-Ray Object properties -> Enable Matte Properties, both works. However, there is issue with Adaptive light mode and LC, so in case that you've found it change the light mode - to Uniform Probabilistic or Full.

Scene File Dim_Distance - 1.zip

Intro : https://drive.google.com/file/d/1a1-...ew?usp=sharing

Cheers,

[RobertRay]

Ho Boyan, thanks for your reply. My evaluation mode already was on full. And it's not the shadows that I have a problem with, but reflection. However, besides that dim distance doesn't work the way I would like, I do have a reflection catcher now. This layer can catch both shadow and/or reflection and is very helpful for placing an object in a picture with a (semi)reflective floor.