Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] Bug Reporting => [Max] Resolved Bugs => Topic started by: CHRiTTeR on 2013-11-19, 05:06:03

Title: VCM not so efficient with blurry refractions? (fireflies bzzzzzz)
Post by: CHRiTTeR on 2013-11-19, 05:06:03
Hi,

I'm new here and verry impressed thus far!

I was verry curious to see how the newish VCM method would perform (this is the main reason i decided to try corona).
Most tests i've seen use perfect glossy reflections/refractions and i find glossy/blurry glass sexy, i thought id test for myself how vcm handles it.
I found out it seems to be quite less efficient with blurry glass...

...or is it a bug? I wonder, because the fireflies have strange positioning (surrounding the object like a glow?)


Anyway, from all the tests i've seen with VCM i thought this render should've been 'done' by now, but clearly its not... (still rendering though, havent cancelled it yet).
Maybe it's me doing it wrong? Mostly using default settings though...


i have a small request/suggestion regarding this too: something like vray's 'affect shadows' option for refractive materials would be verry usefull for fast transparent shadows!


Title: Re: VCM not so efficient with blurry refractions? (fireflies bzzzzzz)
Post by: Ondra on 2013-11-19, 10:01:32
this is most definitely a bug, can you post the scene?
Title: Re: VCM not so efficient with blurry refractions? (fireflies bzzzzzz)
Post by: CHRiTTeR on 2013-11-19, 11:59:21
Sure, here it is.
I cleaned it up a little; removed hidden objects, layers and unused maps. I also converted the glass object to an editable mesh (it was an npower nurbs object).

The settings i changed (and that i remember) are:
Main corona settings:
- max ray depth to 50
- use bdir with vcm
- mat editor quality to 10
- change location of primary solver to d: (c: is my ssd so i dont like it being spammed with writes)
Depth of field/Motion blur settings
fstop to 2
sensor width to 36mm
VFB Settings:
Display AA to 2
[EXPERIMENTAL]Renderer: PT/VCM:
initial lookup radius to 3

Hope you can replicate it and find the little troublemaker!
Title: Re: VCM not so efficient with blurry refractions? (fireflies bzzzzzz)
Post by: iliyang on 2013-11-19, 14:08:43
this is most definitely a bug, can you post the scene?

Please don't make me look bad and fix this ASAP :D
Title: Re: VCM not so efficient with blurry refractions? (fireflies bzzzzzz)
Post by: Ondra on 2013-11-19, 14:25:11
Please don't make me look bad and fix this ASAP :D

Are you open to a little extortion? :D
Title: Re: VCM not so efficient with blurry refractions? (fireflies bzzzzzz)
Post by: CHRiTTeR on 2013-11-19, 17:31:34
Had some more time to play around and apperently, the dof is also acting rather strange...

Heres the exact same scene, but i replaced the glass material with a near white diffuse one.
Left: dof on
Right: dof off
This time rendered using bdpt

Maybe its related to the other problem?
Title: Re: VCM not so efficient with blurry refractions? (fireflies bzzzzzz)
Post by: Ludvik Koutny on 2013-11-19, 17:34:13
What exactly is wrong with that picture?
Title: Re: VCM not so efficient with blurry refractions? (fireflies bzzzzzz)
Post by: CHRiTTeR on 2013-11-19, 17:50:34
What exactly is wrong with that picture?

With that last one?
Notice the hazy/foggy look around the dof... especially at the top of the object, where it is brightest.
Its almost like a glow or ghosting of the object going on.

I think some dof samples might be spread too much out or something?
Title: Re: VCM not so efficient with blurry refractions? (fireflies bzzzzzz)
Post by: Ludvik Koutny on 2013-11-19, 18:55:57
What exactly is wrong with that picture?

With that last one?
Notice the hazy/foggy look around the dof... especially at the top of the object, where it is brightest.
Its almost like a glow or ghosting of the object going on.

I think some dof samples might be spread too much out or something?

Is that VCM or regular path tracing?
Title: Re: VCM not so efficient with blurry refractions? (fireflies bzzzzzz)
Post by: CHRiTTeR on 2013-11-19, 23:48:48
What exactly is wrong with that picture?

With that last one?
Notice the hazy/foggy look around the dof... especially at the top of the object, where it is brightest.
Its almost like a glow or ghosting of the object going on.

I think some dof samples might be spread too much out or something?

Is that VCM or regular path tracing?

Those last 2 (with the white diffuse shader) were done with bdpt, the vcm option was not selected.
Title: Re: VCM not so efficient with blurry refractions? (fireflies bzzzzzz)
Post by: Ludvik Koutny on 2013-11-20, 08:45:12
What exactly is wrong with that picture?

With that last one?
Notice the hazy/foggy look around the dof... especially at the top of the object, where it is brightest.
Its almost like a glow or ghosting of the object going on.

I think some dof samples might be spread too much out or something?

Is that VCM or regular path tracing?

Those last 2 (with the white diffuse shader) were done with bdpt, the vcm option was not selected.

Ah, i see... only progressive integrator is currently fully supported in Corona. If you do just tests of various integrators, then keep doing so, as it helps a lot. But if you want to produce some actual work, then progressive is way to go. BDPT and VCM are not production ready yet :)
Title: Re: VCM not so efficient with blurry refractions? (fireflies bzzzzzz)
Post by: Polymax on 2013-11-20, 13:03:56
Do not use DOF with VCM, it not working properly.
Title: Re: VCM not so efficient with blurry refractions? (fireflies bzzzzzz)
Post by: chilombiano on 2013-11-20, 13:09:47
this is most definitely a bug, can you post the scene?

Please don't make me look bad and fix this ASAP :D

Bulgarian technology! :p
Title: Re: VCM not so efficient with blurry refractions? (fireflies bzzzzzz)
Post by: Ondra on 2014-02-17, 21:09:01
Fixed
Title: Re: VCM not so efficient with blurry refractions? (fireflies bzzzzzz)
Post by: CHRiTTeR on 2014-02-18, 05:21:18
Awesome! I guess i cant download the version with the fix (yet?)