Noise on black

[ous_gt]

Polymax, yours seems very very fast. Can you explain me how you made it faster?

I'm:
1.Use portals
2.Use pt=16 + HD(512)
3. Resolution 720p
4. Albedo down to 0.7-0.8 diffuse level
I have more faster CPU than yours (i7 980 - 4GHZ)

Thanks very much. I should ask, i couldn't find portals. Where should i look?

[Ondra]

Great tests maru. Based on your tests, i can say, the lower diffuse level is, the faster rendering. As i understand, reducing general diffuse level is basically the same thing to reduce ray depth, because models reflect less light to others. That's why it's getting faster and faster if you keep reducing diffuse level. Is that correct?
If that's so, is it okay to reduce ray depth and keep diffuse levels all 1? Is it the same thing?

it is not exactly the same. Lowering ray depth is incorrect, since it is biased, but lowering materials albedo is not (but you change the scene description). So in one case you get darker image because you render bright scene wrong, in the other you get darker image, because you render a different, darker scene correctly. I would suggest just experimenting and using the approach that gives you best results with respect to time, quality, and freedom.


Portals are done by assigning a CoronaPortalMtl to any geometry.

[ous_gt]

Great tests maru. Based on your tests, i can say, the lower diffuse level is, the faster rendering. As i understand, reducing general diffuse level is basically the same thing to reduce ray depth, because models reflect less light to others. That's why it's getting faster and faster if you keep reducing diffuse level. Is that correct?
If that's so, is it okay to reduce ray depth and keep diffuse levels all 1? Is it the same thing?

it is not exactly the same. Lowering ray depth is incorrect, since it is biased, but lowering materials albedo is not (but you change the scene description). So in one case you get darker image because you render bright scene wrong, in the other you get darker image, because you render a different, darker scene correctly. I would suggest just experimenting and using the approach that gives you best results with respect to time, quality, and freedom.


Portals are done by assigning a CoronaPortalMtl to any geometry.

Thanks. It's really exciting to test this engine Keymaster. Good work.

[ous_gt]

edit: something was wrong with 3ds max i guess, closing and opening again fixed it.

[ous_gt]

Well, you should be sick of this scene but here are my last tests.
With portals and other advises, i've made some changes. It looks better and calculates faster.
There's one thing i noticed is that resolution makes a huge difference at render times. I've attached two images, both 125 passes. Check the difference at render times when you increase resolution from 720p to 1080p.

[Ondra]

yes, double the resolution, double the render time. Unbiased methods work in this way, compared to irradiance caching, which is rather dependent on scene complexity.

[ous_gt]

It makes sense.

I was gonna leave this scene but, i think i have more things to learn from it. So i was rendering from this angle, it's been 200 passes but the black part is still noisy. 200 passes should be enough for a scene right?

I used portals. I reduced albedos. Using PT(25) + HD(512).

I just can't figure it out and that makes me crazy about this scene.

update: in this scene, even 300 passes doesn't make the reflective black material smooth. It gets smooth when it's too reflective, or not reflective. When i adjust it the way i want, it doesn't get smooth. I've tried to lower reflection amount by changing frensel IOR or reflection level. It didn't make any difference. 300 passes and it's still not smooth.

[maru]

Looks like it's because of your strange material setup:

-reflection level: 1,0
-fresnel IOR: 1,1
-glossiness: 1,0

Changing ANY of these parameters to something more realistic like reflection level 0,9 OR fresnel 1,5 OR glossiness ,95 (or preferably all of them) makes it clean much faster.

[ous_gt]

I've tried different settings too. That was my last hopeless try:) make frensel 1.5, reflection 0.1. That's kind of what i want from it. place a chamferbox at the center of the scene. when you have low reflection, it takes much more time if you compare it to a more reflective material. Like i said, it takes more than 300 passes to clear up.

[maru]

Strange. I opened your scene, switched to pt+pt, changed material's params to something like:
refl: ,8
fresnel: 1,5
gloss: ,9
and after 25 passes it was less noisy than yours...

[ous_gt]

Try;
refl: 0.1
fresnel: 1,5
gloss: 1

if this one works fine too, then i will merge my scene to another or try to find a problem with my pc.

[maru]

Captain, looks like we have a bug here.

[ous_gt]

So the glossiness amount is the reason huh. who knew. Good work maru. I'm using 0.95 and it seems fine.

[ous_gt]

What could be the reason for the white dots both on the mirror and the glass? I thought it was the glossiness but i never used glossiness 1.0.

[ous_gt]

This is how mirror looks at first and it never clears up. Here's the scene, too.