Long render time + lot of noise

[Fabrice]

Hi
I'm rendering an landscape animation but my rendertime are very long (more than 30 min/frame) and the result is very noisy.
Rendertimes are very important (more than 30mn!!!) and still very noisy
but the scene is quit simple :
- a ground (no displacement)
- a few bitmap sprites particle for the trees
- HDRI (512x256 pixel) environnement for the lighting
and that's all.

Any advice about how to decrease render-time and get rid of the noise?
Tahnks
----------------
Octane 3.03.4 - 4.21
Max 2014
Win7 pro
RAM 24 Mo
-
GTX 980ti
GTX 780

[mbetke]

Using alphas for vegetation is really compute intesive. You will get faster results using "real" instanced geometry with moveable proxies.

[Fabrice]

I agree.
But if I remove the particle trees, rendertime is still 12min wich is quite long for a plane and 10 lathe objects on it.
(and still grainy)

[promity]

If you use Path tracing or PMC render kernel - set GI clamp to 2 - it help to reduce a lot of render time.

[mbetke]

maybe share your settings here so we can take a look

[paride4331]

Hi Fabrice,
You probably are not using imp. Sampling or you modified the evironement mapping transformation and this generates noise issue.
viewtopic.php?f=80&t=60992&p=312417#p312377
Regards
Paride

[Fabrice]

Here it is.

[promity]

Ok, go to Path Tracing tab -> GI and change '1000000' to '2'. After that go to Kernel settings -> Max samples and change it from 16000 to 500-1000.

[Fabrice]

Thanks Promity!
but with GI clamp set to 2 instead of 1000000 :
- rendertime is extremely shorten (cool)
- BUT no more light seems to be entering the scene. There is allmost no more bright zone on the objects. I'll try some higher values...