OTOY Forums

Hi all

after some time testing with simple geometry I´d like to get a more complex scene to work with octane. But I am confused since after 7,5h rendering the picture is far from beeing cleared even in uniform non specular areas. Maybe someone could have a look at my specs and at the picture and give some impression whether the times are plausible.

I did the pic on pathtracing kernel and let it render to 64.000 s/px

Cheers,
Rogurt

hm, this is a problematic setup in general; lots of small light sources + environmental light, lots of glossy mats, only one entry for sunlight/env.light. you should have a look at the sample_rate parameter in the emitter, to boost the samples of the smaller lights; pmc and playing with the direct_light_importance may give better results; maybe a reduced maxdepth for better speed, and the use of a portal (normals inwards!) covering the door could also help...

I'm not sure if that's the case, but try to decrease the hotpixel_removal setting a little.

thank you guys for your advice. I made some testing and maybe you´re interested in the results.
I tried to tweak the kernel settings as to give indirect lighting more processing time and to have more paths evaluated than going too deep into single paths. Next I tried to add portal and further tweak the sampling settings of the spot emitters (IES) on the ceiling.

In short: portal does a really good job - noise of environmental lighting gets reduced quite well
tweaking sampling time of bright spots does the rest - shadows and lighting in according zones are way better (less grainy).
So most of the time I think one can spare the fumbling in the kernel except for the bounce depths..

But see yourself
1 all settings default except for depth=6 alphashadows=off
2 exploration strength from 0.7 to 0.15 -> grainier less fireflies
3 exploration strength from to 1.0 -> more noise and more fireflies than initial setting (0.7)
4 direct light importance set from 0.1 to 0.02 -> again more noise than initial setting and more fireflies
5 simple plane portal used in front of windows -> way less noise
6 tweaked sampling of main Spots in ceiling -> less noise in spot lit areas/shadows

try to render with a 3x higher resolution and then downscale to the size you want ,your picture
will clear much faster
Rico

thanks for the advice. it really shows less noise when calculating for the same time with 3 times resolution than downsampling to original size (PSD standard filter). In addition the picture is remarkably sharper with more details where small dark features stand in front of a very bright background.
So that seems to be a really good thing to do...

I must correct my remarks on test #5. The portal does not seem to give remarkable noise reduction in that scene compared to standard setting (#1). Must have compared it to other pic than #1...

Edit: sample rendering attached

Edit: Pathtracing was the kernel here.

Thought Pathtracing would be a lot faster. But as it seems after 8.40min the picture is not as consistent as PMC version (compared to test #6). In some areas less noise (shadows on floor) but the fireflies give me some extra time in Photoshop. I already had the hotpixel removal reduced to the lowest value that wont let small picture parts vanish...

Is there some rule of thumb as: in interiour scenes with much indirect lighting pmc is superiour in terms of quality AND speed or the like?
What unbiased kernel do you guy prefer?

For completeness rendered again with direct lighting kernel. Result surprises me. While there´s less noise in indirect lit/shadow areas there are lots of fireflies in the render. Also I thought taht the overall appearance would differ from the two pictures due to completely different kernels. But it´s quite the same.

So the big final conclusion. Drop everthing but PMC? I remain confused.

Any help for orientation appreciated...

Cheers,
Rogurt

Addendum: kept the bounces throughout all different tests/kernels at 6

Rogurt wrote:For completeness rendered again with direct lighting kernel. Result surprises me. While there´s less noise in indirect lit/shadow areas there are lots of fireflies in the render. Also I thought taht the overall appearance would differ from the two pictures due to completely different kernels. But it´s quite the same.

So the big final conclusion. Drop everthing but PMC? I remain confused.

Any help for orientation appreciated...

Cheers,
Rogurt

It depends on the scene. For scenes with a lot of glossy and specular surfaces or with lots of light sources PMC will work the best. For scenes with simpler lighting path tracing may work better.

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Roeland

Hmmm, I'm wondering what kind lights your using. I was having the same problems with my scene until I scaled down the IES emitters. sharpened the lights and dramatically reduced the noise emitted.