Adaptive Subdivision vs. Adaptive QMC

[flipside]

Try 30 subdivs for the glossy material, and 0.001 for noise th in the QMC rollout, global subs=1.

Don't be fooled by the global multiplier, here's how it works:

local subs=8
global=15
result: 8*8*15=960

local=30
global=1
result: 30*30*1=900

So 15 global is not really that much, and multiplying global with 2 is not the same as multiplying local subs with 2.

I always use local=30 and global=1, with 0.001 noise th and glossies are perfect. I'm on max 5 so I can't open your file...

[flipside]

In a test like yours, adaptive subdivision is probabely faster for the same quality, but in a scene with lots of glossies, area lights, displacement, trees, etc... qmc AA is definately faster.

Here's my test:

Materials glossy 30 subdivs, adaptive sub AA 0/3, qmc noiseth=0.005



Materials glossy 30 subdivs, adapt QMC AA 1/4, qmc noiseth=0.001 (=900 samples in total)



Materials glossy 8 subdivs, adapt QMC AA 1/4, qmc noiseth=0.001, global subdivs=14 (=896 samples in total)



The adaptive subdiv test is a little bit better, but adjusting the material subdivs to 35 would solve this. Already in this test, adapt QMC is faster for the same quality, imagine what it would do in a more complex scene! It definately rocks

[Gijs]

Percy,

just tested your file. Try for example min samples = 16 and global subdiv. = 16 and noise treshold = 0.001 and you wil get the same quality with faster rendertime. (AA adaptive QMC settings default)

[percydaman]

thanks for the help. The thing is, I kinda knew if I upped the material glossy subdivs it could smooth them out, its just that it didn't seem necessary if I used adaptive subdivision. Even default values of 8 looked great. Seemed strange to me. But I can see Ill just have to go at it that way. Thanks again.

[flipside]

There's something about AA in the helpfiles which explains why adapt QMC or even fixed is faster than adapt sub with lot's of glossies or other blurry parameters (MB, area shadows, ...). I think the reason you need to up the material subdivs is related to that.

[percydaman]

Thanks. I definitely remember that from the help file. Unfortunately Im still having issues.

I tried a render with your settings:
Adaptive QMC 1,4
Material glossy subdivs:50
QMC noise amount:.001



Here are render settings with Adaptive Subdivision:
Adaptive Subdivision 0,3 threshold .05
Material glossy subdivs:8
QMC noise amount:.005


If you again, take those into the ram player and scrub between the two, its very apparent on the chair and wall to the left. The floor looks pretty similiar now, but the fine detail on the wall is causing major noise using the adaptive qmc. So it appears to be related to fine detail with textures not just glossies?

Once again, the speed differences are apparent, but dont know what I can do to up the quality of the adaptive qmc version. I dont mind if it takes as long as the adaptive subdivision at this point. I mostly wanted to use it for its smaller ram requirements. This scene is at 1.79gb when rendering with adaptive subdivision and its just the bare start of the scene! Rendering with adaptive qmc nearly halves the needed memory.
Ill email ftp link to you morbid angel. Beware though its 25mb and has some large textures.

flipside: I wish you had max 6...lol

[flipside]

Yeah the AA affects textures as well. Regarding your wall, in fact the adapt QMC version shows more detail, that's why it's noisy. The adapt sub blurs it out a bit. It's like when switching from catmull/rom filter to mitchell/netra for example. The catmull will make everything look sharper.

Maybe these AA filters can help you smoothing out the noise on the wall? Which one are you using now?

[flipside]

Mmmm this makes me think you have a texture on the sofa too? Or a bump texture? Probably with only color and glossy you don't have the problem, can you try that?

[percydaman]

yeah I can try later today. There is a texture on the couch. My issue with the wall is of animation. I would need to do a animation test to see how the noise looks across several frames.

[Morbid Angel]

damn...im still on vray 10, so cant render the same result as yours...

[percydaman]

wow is it that different? hmmm ive tried both latest version at home and version .14 at work and while im not sure if they came out exactly the same, the issue didn't change that I could see.

[flipside]

I did another test, more like your sofa.

It's a chamfer box with a material that has a fine leather bump on it.

The reflection glossy is set to 120

QMC AA


ADAPTIVE SUB AA


QMC AA, no bump texture



I used catmull rom to better see the effect.

Weird thing is that I don't get a smooth result with adapt sub either. It shouldn't be too smooth though because there is a bump so it should look bumpy

[percydaman]

egads 120 subdivisions? Man i remember when anything above 8 just crawled.... okay so maybe the adaptive subdivision is blurring too much? I was using catmull rom as well, it just looks so much better compared to the others. Could just be in my head though. Maybe the noisier result is showing better detail.

[flipside]

Maybe the noisier result is showing better detail.

That's what I was trying to say Especially for your wall I'm sure it's just showing more detail instead of blurring it like the adapt subdivision does. Don't think it will give you problems in the animation?

[Morbid Angel]

percy...why your scene renders for so long?..
i cant get the correct result (like your render) but even then there is nothing there and the rendering is huge...