Something is wrong with refractions

[gagui]

Hello.

I'm having some extrange behaviours with glass materials. I have 3 glass panels, the objects seen through them seem to loose their reflectivity even if I up the ray depth to 50 in refraction, reflection and global.
Not only that, when I have only 1 or 2 panels the reflectivity of the objects seen through is there but the distortion of the refraction is lost. However this distortion is ok when there are 3 or more panels.

I've attached 3 pictures where is explained and the original scene.

I'm on houdini 19.0.498 python 3 and last vray nighly version but I've checked this behaviour in last official stable on 455 aswell.

[chakarov]

Hello gagui , I am not sure that so much refraction distortion is normal, especially for IOR 1.3.
In your file refraction trace depth of glass material is set to 50 /which renders fine in production/, but I guess the screenshot is got from IPR - where reflect/refract trace depth is limited to 5 by default, you can change this setting in V-Ray ROP > Renderer > IPR > Trace Depth
Reflections of red object is not visible through 3 glass objects because of reflection trace depth for it's material is set to 5, if you set it to 7 or 8 it will be rendered as expected.
You can control both reflect and refract trace depth for all the materials in the scene from V-Ray ROP > Renderer > Options > Materials > Global Trace Depth

[gagui]

I see. I didn't notice that there's a separate trace depth parameter for IPR. Good to know

Thanks!!

[gagui]

Hi Georgy.

I'm still experiencing some inconsistencies related to Max Depth in refractions and reflections between CPU and GPU renderers.

I'll try to explain:

In the scene attached I have 4 sheets of glass. All materials have max depth at default 8 in refraction and reflection
In CPU with Global Max Depth and IPR max depth settings at 8 the render misses the reflections of the red shape and the ground seen through the sheet glasses as expected because there aren't enogh rays.
So if we raise this globals to 10 it renders ok in IPR and Production. So I assume this globals both act like globals "overrides".
Ok cool, that makes sense but in GPU is not working like that.

First thing I see when I change to GPU render is that the Global Max Depth setting is not there. So for GPU production render I have to raise Max Depth for each material. I asume this is a thing to add to the wishlist, ok.
But in GPU IPR we stll have the dedicated Max Depth setting wich is meant to act like in CPU, a global "override" but is not.
With all materials Max Depth at 8 if we have GPU IPR Max Depth set it to 10 we still don't see the reflections of the ground and red shape through the glasses we need to raise also the Max Depth in the materials.
If I leave the GPU IPR Max Depth at 8 and raise all materials Max Depths to 10 it still misses the ground and red shape reflections.
So in this case the GPU IPR Max Depth is acting more like a limiter instead of a global "override".

To resume: in GPU a global Max Depth is needed. Also this and IPR Max Depth should act as a global override and not only as a limiter.

I hope all this makes sense to you.

I'm using Houdini 19.0.531 and Vray build 22071 over windows 11

[Muhammed_Hamed]

Hi gagui

Thanks for the report. We are aware of this behavior, it is near the top of our current priority list.
We already planned a solution for this, the GPU will behave like CPU and the global Max Depth setting will work on GPU and be part of the global overrides.
I will update the thread when this change is live.

Best,
Muhammed

[gagui]

Cool!

Thanks Muhammed.