Path guiding (experimental)

[jackieteh]

Hi,

Thank you for the new update, may I know if this Path guiding (experimental) is compatible with the AMD pc?

[^Lele^]

I have tested it on an AMD myself, and it showed improvements.
Notice it may also turn out slower.
It's very scene dependent, and the library itself is at version 0.4.0.
So, expect surprises.

As a further note, we currently have some tech which is faster than PGL for specific effects (f.e. the progressive caustics).
This may change as PGL and our techs mature, but don't expect night-and-day differences, just yet.

All this said, feel free to try it out under any imaginable condition, we're all ears as to the results.

[^Lele^]

we will update the documentation soon but here's the preliminary info that you might want to keep in mind about it:

- supported by: vraymtl, env fog with enabled GI, volume grid with enabled GI
- helps in scenes where GI/glossy reflections are hard to sample (e.g. a lot of occlusion, interior scenes, etc.)
- usually requires at least 1000 LC subdivs, some scenes might get better results with around 3000
- only CPU (GPU support is planned by Intel, with no current ETA.)
- uses Intel's OpenPGL library.
- still work in progress/experimental feature, support for more materials and some optimizations are coming
- it will produce different results compared to normal rendering if secondary ray clamp (enabled by default) or subpixel color mapping (disabled by default) are enabled. It might produce different results in the raw render elements (depending on the material and lighting) but they should still produce the correct result when multiplied by the respective filter RE.
- it might produce different results compared to normal rendering for diffuse surfaces with low poly counts (depending on the geometry, materials and lighting)

[flat]

Is it necessary to disable the VRayVolumeGrid's "Volume Light Cache" in order to apply Path guiding with the VRayVolumeGrid?

[dian.nikolov]

You don't have to disable Volume Light Cache. Path Guiding will be used in its calculation in this case.

[flat]

Thank you for the information.

However, it is very difficult to feel the effects of this feature.

[^Lele^]

Thank you for the information.

However, it is very difficult to feel the effects of this feature.

As mentioned, it's very scene-dependent.
I managed to have it shave a whole 20% in a specific scene (which had nothing special to the setup. run-of-the-mill interior lit with outside sun and sky), and for that scene, the camera location didn't matter, the performance increase was present everywhere, and it would be visible while the render was going, thanks to a much less busy (and red) sampleRate RE.
Other times, the PGL would offer absolutely no gain, and in some case it even made the render (marginally) slower.

As the library itself matures, we may see a more reliable improvement across the board, save for where we may be already quicker with our own tech.

[jackieteh]

Thank you for the information.

However, it is very difficult to feel the effects of this feature.

Agree with you, this is why I ask is this feature support AMD, because I am using AMD machine