Diffuse Kernel Redundant?..

[MrFurious]

Since Octane 2.0 I've been running comparisons between the Diffuse Kernel and Path Tracing. With the noise/firefly issue with the initial 2.0 release and subsequent fixes I've been keeping a close eye on the diffuse kernel to see how things have improved. To the credit of the Octane team the firefly issue seems to have been fixed but I can't help but notice that in every rendering situation I've tested, Path Tracing is faster than Diffuse. And now with GI Clamp built into PT I'm wondering what's the use of the Diffuse Kernel, it now seems redundant.

note: all testing done with the LW plugin which is why I'm posting it here. Will endeavor to test it with standalone asap.

[geo_n]

Pathracing is still 25% slower in my test.

[MrFurious]

hm.. will have to upload a sample scene

[MrFurious]

geo_n was your test in LW or standalone?

[geo_n]

Lightwave. Upload a sample scene.

[MrFurious]

The thing to remember when testing is the Diffuse depth should not be set the same for both. Diffuse Kernel requires less diffuse depth samples to achieve the same visual result. Here's my very basic and preliminary test. By that I mean it does not have any glass or refractions. It's the standard benchmark for LW. Here goes..

STANDARD LW BENCHMARK SCENE
DIFFUSE KERNEL
1000 Samples, Diffuse Depth 2, Specular Depth 4, Glossy Depth 4

MS/sec = 19.20
Rendertime = 00:12


PATHTRACING KERNEL
1000 Samples, Diffuse Depth 3, Glossy Depth 4

MS/sec = 19.14
Rendertime = 00:12

The difference is negligable so spec-wize I'd call it a draw. Visually though PT appears to resolve faster.

[MrFurious]

Second test, my interior scene. I can't upload this scene but it'll do just to demonstrate.

TYPICAL INTERIOR SCENE
DIFFUSE KERNEL
1000 Samples, Diffuse Depth 3, Specular Depth 12, Glossy Depth 12

MS/sec = 2.86
Rendertime = 01:23

PATHTRACING KERNEL
1000 Samples, Diffuse Depth 4, Glossy Depth 12

MS/sec = 2.86
Rendertime = 01:22

And the winner is.. PT! Only by a whisker but still faster. Whats more important here though is PT has clearly resolved better.

So..
faster (ok same speed more or less) by using more diffuse samples (?!@$?) and looks better.

[MrFurious]

Similar results in Standalone for the Benchmark Scene

STANDARD BENCHMARK SCENE OCTANE STANDALONE
DIFFUSE KERNEL
1000 Samples, Diffuse Depth 3, Specular Depth 4, Glossy Depth 4

MS/sec = 17.72
Rendertime = 00:34


STANDARD BENCHMARK SCENE OCTANE STANDALONE
DIFFUSE KERNEL
1000 Samples, Diffuse Depth 2, Specular Depth 4, Glossy Depth 4

MS/sec = 18.84
Rendertime = 00:32


STANDARD BENCHMARK SCENE OCTANE STANDALONE
PATHTRACING KERNEL
1000 Samples, Diffuse Depth 3, Glossy Depth 4

MS/sec = 18.80
Rendertime = 00:32

With the Diffuse Kernel at 2x diffuse samples it was the same rendertime as PathTracing at 3x diffuse samples. With the diffuse samples set the same PT was faster. I've compared apples with apples here just as with the LW test, tried to keep all other settings (other than the render kernel) the same. for some reason in standalone the PT test is a bit brighter, but once again it's faster than, or equal to diffuse.

[geo_n]

The thing to remember when testing is the Diffuse depth should not be set the same for both. Diffuse Kernel requires less diffuse depth samples to achieve the same visual result. Here's my very basic and preliminary test. By that I mean it does not have any glass or refractions. It's the standard benchmark for LW. Here goes..

STANDARD LW BENCHMARK SCENE
DIFFUSE KERNEL
1000 Samples, Diffuse Depth 2, Specular Depth 4, Glossy Depth 4

bm test diffuse kernel.jpg

MS/sec = 19.20
Rendertime = 00:12


PATHTRACING KERNEL
1000 Samples, Diffuse Depth 3, Glossy Depth 4

bm test pt kernel.jpg

MS/sec = 19.14
Rendertime = 00:12

The difference is negligable so spec-wize I'd call it a draw. Visually though PT appears to resolve faster.

There's more noise I see in your pt render. Same thing I notice with mine. Needs more samples to get rid of noise which means more time.
For the interior let them resolve till there's very little noise and post render time.

[MrFurious]

Are you sure have a closer look at the walls and in corner areas, its more course noise with Diffuse. Look at the rug, more detail can be seen in the PT render.

Will let it resolve more and see how it looks.