Production rendering on GPU incorrectly uses RT Max Trace depth

[1funk]

Production rendering on GPU is still using RT Trace depth, when it should be ignoring it. CPU renders do this correctly.

I have a material in this scene that has reflection MAX DEPTH set to 24

1. Load attached scene
2. Ctrl+click the green teapot in the vray toolbar to start a production GPU render

RESULT: The reflection under the cube is black. This is incorrect, because RT trace depth is limiting the max depth.
RT trace depth should NOT be used in a production render. Only in RT.

3. Change RT TRACE DEPTH from 5 to 24
4. Ctrl+click the green teapot in the vray toolbar to start a production GPU render

RESULT: The reflection under the cube now uses the max depth correctly and looks redish


Here are the results side by side:
Left = GPU production render with RT TRACE DEPTH of 5
Middle = CPU production render with RT TRACE DEPTH of 5
Right = GPU production render with RT TRACE DEPTH of 24

[vladimir.nedev]

That's how it works in V-Ray for Max/Maya too from what I've tried.

I can fix it in the exporter, but this will mean the ray depth will depend only on the materials, as "use global max depth" is disabled by default, and I am a bit reluctant to do that.
I am not sure whether all material types properly respect the per-material max depth.

Greetings,
Vladimir Nedev

[Muhammed_Hamed]

I can fix it in the exporter, but this will mean the ray depth will depend only on the materials, as "use global max depth" is disabled by default, and I am a bit reluctant to do that.

In my view, I think fixing it in the exporter is the right call, this is how myself and others would expect it to work
I originally suspected it was bugged and didn't know RT settings affect production rendering.

I am not sure whether all material types properly respect the per-material max depth.

This seems to work here, but will let you know if something is not working.

Funk Thanks again for reporting this, very massive for what I do

[1funk]

That's how it works in V-Ray for Max/Maya too from what I've tried.

vladimir.nedev I really think this is a design flaw you need to discuss with vlado and the team. Right now, a user would need to constantly change RT trace depth each time they want to do a GPU production render.

RT settings should only affect RT (to help make interactivity faster).

Maybe we really need a "production" (main settings) version of any affected RT settings, so they can be used for production renders. (we already have progressive sampler GPU ray bundle size, GPU rays per pixel, max render time, noise threshold etc)

I can fix it in the exporter, but this will mean the ray depth will depend only on the materials, as "use global max depth" is disabled by default, and I am a bit reluctant to do that.
I am not sure whether all material types properly respect the per-material max depth.

So what is the CPU renderer doing? It looks like it's using the material max depth, but you've stated this may not be respected by all materials. What happens in those cases on CPU?

[boyan]

Hey, All

The fix was added to the nightly build https://nightlies.chaosgroup.com/mai...ghtly/20190617

Cheers,

[boyan]

Hey,

Sorry I've been deceiving you. This one is in progress.

Cheers,

[vladimir.nedev]

For today's nightly build ( 2019.11.05 ), I've removed the "trace depth" option in the RT tab, the "Use global depth" option in the Main tab, and the per-material reflection/refraction depth options.
The new default for the global reflection/refraction depth is 24.

I did a few tests, and scenes without refraction (only reflection/diffuse) don't seem to be affected much. This includes a quite complete Evermotion scene.

With refraction, rendering can be ~40% slower (almost twice as slow), if the whole frame is covered by the refractive object.
But most of this slow down comes from going from 5 to 8 or 12 bounces.
Naturally, the refractions are much more detailed.

So, this in a way fixes the original issue, as the option doesn't exist anymore.

Greetings,
Vladimir Nedev

[1funk]

Thanks vladimir.nedev