OTOY Forums

Dear All,
I'm having issues with one of my spare time task. I'm using instances of a table and instances of light, so on the attached screenshot, the two tables are exactly the same, as well as the light litting them is the same, however, the one on the leftclears up really quickly, but the other won't. Even if I reach the max sample set to 10.000. I tried to use region render to clear that area, but it never gets better. I'm using PT kernel. The light is IES light. What should I change? Thanks for your efforts in advance!

Hi,

I've noticed several inappropriate settings. Briefly:
• sky-rocketed ray depth values
• excessively high camera imager's exposure, implying a weak lighting ("intensity" wise) which leads to less "energy" in the scene (lighting wise)
• caustic blur and GI clamping
• parallel samples at default
and some more.

I would presume that you are not familiar with all these settings. As there is much to cover, I prefer to forward you to online resources that cover all the above:
• OctaneRender® Lighting
https://skientia.co/cgi/octane-lighting
• OctaneRender® Kernel Settings
https://skientia.co/cgi/octane-settings
• OctaneRender® “Color Management”
https://skientia.co/cgi/octane-colormanagement

Regarding your issue, without more scene information, I can only guess that
• there might be inappropriate values on that IES light,
• the scene layout isn't in favor to that light
• or just a light sampling-rate matter

The answer is somewhere in all the above.

Hi elsksa,
thanks for the feedbacks and to point on the weak points in my settings. However, specular depth is set to this amount to avoid the black areas behinde the glasses on the other parts of the scene (a lot of glasses next to each other, like in a bar).
I'll read the pages you copied me, thanks!
I accept of course if the wrong settings cause the issue, but then why it affects only a few object in the scene? This is strange for me.

You're welcome.

I was not referring to the specular ray depth, although it is quite high for the type of scene. However, I'm not seeing all elements. I was rather referring to the scatter one, which I presume is not relevant to the scene but excessively high.

In the Octane Kernel Settings page, have a look at the GI Clamping section.

After discussing with an other user facing a near identical case, it seems to be related to the Adaptive Sampling section from the Kernel settings. I'd suggest to reset it and cautiously setting it back as it will most likely solve the occurring "black dots sampling issue". Raphael Rau (Silverwing VFX) has a YouTube video on Adaptive Sampling.