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Hi,

ive not used octane for a year or so because meshemitters worked very slow and there was no solution for complex lightning. After ive seen that finally pmc is implemented, a gave it a try again

So, I loaded my glass-scene into max and exported it to see the outcome, well pmc is great!

But I have to say, that compared to my rendering I did with luxrender, octane is not faster, BUT the results are nearly the same
But I noticed, that when I put the lightsouce out of the glass, the whole render seams to lag on caustics somehow.
Hope you like them

Hi,

How long have these been rendering, and how does the second scene look if you render it with hotpixel_removal set to 1.0 (= off) ?

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Roeland

Hi,

the first scene took 7 hours to render on my gts 250m.

The second scene took nearly the same except some hotpixels from the first pure pathtracing samples.

PMC seems to not generate any hotpixels at all

Placing a emitter inside a refractive medium is never a good situation for any unbiased engine

Cheers,

Chris

I know, thats why I tested it because I didnt expected pmc to handle this scene that great!

To make it a fair test you should use the same alghorithms,
if you use bidir/MLT in luxrender you will get efficient rendering of caustics due to the lightpaths.
PMC/pathtracing (what octane does with 'PMC' enabled) should be compared with MLT/pathtracing in any other engine for a fair comparison on this particular type of scene,
which is about the worst you can get for a pathtracer (not for a bidirectional pathtracer)

Radiance

It will be real in the future that octane will get faster or more efficient alghoritm? Because the curent PMC is not so efficient for interiors.

Is bidir/PMC something that is plausible for octane? is it being planned/worked on?

I hope they will implement bidir or something like a prepass for caustics...because at the moment its very hard to get them right.
I need them mostly for water/pool caustics only option for now is to fake them with generators

Caustics on glossy materials are actually very fast and good looking. But on refractive they are relatively slow and on pmc it needs >1000 samples until they are as bright as they should be. Also on pmc it looks like it darkens refractive materials a lot, most with a high exploration_strength or with a very low direct-light-importance.

Anyway...
Radiance said I should use the pathtracing/mlt instead of biDir/mlt in Lux to get a fair comparison. Now I did. Now also Lux has a hard time to find new paths trough the glass because no directlight can be traced, but if it finds new ones it really samples the ones found way better and refractive caustics appear faster. After 7 Hours, both noiselevels of Lux and Octane nearly where the same and in my opinion the result in terms of realism looked slightly better in Octane.

Ok but I have to say that I just have a gt250m GPU in relation to a Core I7 at 1,6Ghz, so my GPU is very low end.