2.40.04 VrayDirt through output map does not work anymore...

[LudvikKoutny]

Hi,

i just discovered that color correcting VrayDirt map using output map does not seem to work in 2.40.04. As you can see on the attached picture, output without any modification of VrayDirt is identical to the output of VrayDirt fed through the heavily color mapped output map.



This makes me very anxious realizing all my renders i did with 2.40.04 were rendered wrong (i wondered where all the detail went) and that all my materials i did while using 2.40.04 will look very different once this gets fixed. I used VrayDirt fed through Output map a LOT for creating procedural materials...

I will have to fix a lot of stuff on the large project i am currently working on, let alone fix will probably take ages before next Vray 2 version is released... :/

I am attaching also the scene

EDIT: Forgot to add it is on Max 2014 SP3

EDIT2: Just to double check it is really Vray issue, and not 3ds Max issue, i created the same scenario with Mental Ray and everything worked the way it should.

EDIT3: Does not work though Color Correction node either.

[matanov]

Thanks for the pointer !

[LudvikKoutny]

Please let me know as soon as this is fixed.

[vlado]

I don't think there's any bug here. Can you try using more subdivs for the VRayDirt map so that you get a clean result before it is passed to the Output map?

Best regards,
Vlado

[LudvikKoutny]

I don't think there's any bug here. Can you try using more subdivs for the VRayDirt map so that you get a clean result before it is passed to the Output map?

Best regards,
Vlado

1, I did try to increase subdivs, same result, just cleaner.

2, In all previous vray versions, it worked perfectly... you yourself sent me an example of it... in this thread http://forums.chaosgroup.com/showthr...167#post573167

3, As i stated above, i tried Mental Ray as well, and result changes dramatically when output map with same color mapping is plugged in.

The biggest problem is that i am in a middle of a project that has a deadline, as most of them... And major part of my workflow revolves around procedural materials, that presents several problems:

- I have to go back through all the scenes in this project created with 2.40.04 and fix the materials with some different method, if i find one

- I will have to fix many of my materials once this issue gets resolved as i have been making them from since the beginning

- I am really stuck before until this gets fixed, because i still can not find substitute workflow for procedural weathering effects

[LudvikKoutny]

Now this is funny.... This is what i got when i lowered Max DMC subdivs from 100 to 4... It is rendered on a SINGLE machine, with DR disabled... O_O

[LudvikKoutny]

Ok... so i narrowed down the source of that issue... color mapped VrayDirt behaves extremely unpredictably regardless of what amount of subdivs is set in VrayDirt when using Vray universal settings approach.

EDIT: Examples:

In all of the examples below, VrayDirt Subdivs are set to 64

Max 4 DMC samples


Max 16 DMC samples


Max 32 DMC samples


Max 64 DMC samples


I guess sample division is really bad thing in this case, as it does not affect only quality, but also the look of an output.

[kosso_olli]

I just tried it today, VrayDirt in Output-Map or even ColorCorrect works as expected. Same version of vray as yours.

[LudvikKoutny]

I just tried it today, VrayDirt in Output-Map or even ColorCorrect works as expected. Same version of vray as yours.

Could you try with high Max DMC subdivs?

[vlado]

color mapped VrayDirt behaves extremely unpredictably regardless of what amount of subdivs is set in VrayDirt when using Vray universal settings approach.

For the VRayDirt subdivs to have any effect, they need to be more than the subdivs of the AA sampler.

I guess sample division is really bad thing in this case, as it does not affect only quality, but also the look of an output.

It's good that we added that option then, isn't it The general problem is that one sample of VRayDirt is either black or white; whatever your Output curves are, the black will remain black and the white will remain white. You need more samples for each shading point in order to make any mapping meaningful. In order to do that with the universal approach, you'll need to increase the dirt subdivs beyond those of the AA sampler.

Best regards,
Vlado

[LudvikKoutny]

For the VRayDirt subdivs to have any effect, they need to be more than the subdivs of the AA sampler.

It's good that we added that option then, isn't it The general problem is that one sample of VRayDirt is either black or white; whatever your Output curves are, the black will remain black and the white will remain white. You need more samples for each shading point in order to make any mapping meaningful. In order to do that with the universal approach, you'll need to increase the dirt subdivs beyond those of the AA sampler.

Best regards,
Vlado

Ohhhhhhhhhhhhhhhhhhhhhhh... That's few of those things that are not written anywhere yet everyone should know... It is quite confusing when setting, which you expect to only affect quality/speed ratio, affects actual look of the image as well... It's nice that now we have option to disable sample division. It does not really bring that much of a performance gain, but it certainly makes things easier to set up.

[LudvikKoutny]

Well, i am lost again

I started to use low Max DMC subdivs ( 8 ) but now whenever i render for example cars with chrome parts under sunlight with motion blur, i get fireflies that flicker from frame to frame instead of smooth sundisk reflection. I need those sundisk reflections with their correct HDR intensity to generate glares out of them in post, but i also need to have color mapped VrayDirt working, so i can not get very high with Max DMC subdivs. I am trying to increase motion blur subdivs, but each 4 additional subdivs in motion blur mean another 100% of rendertime. So 16 MB subdivs already means 400% growth from original rendertime, let alone that i need at least 40 MB subdivs to get something close to clean sundisk reflections. I have really no idea how to solve this.

[vlado]

I started to use low Max DMC subdivs ( 8 ) but now whenever i render for example cars with chrome parts under sunlight with motion blur, i get fireflies that flicker from frame to frame instead of smooth sundisk reflection. I need those sundisk reflections with their correct HDR intensity to generate glares out of them in post, but i also need to have color mapped VrayDirt working, so i can not get very high with Max DMC subdivs. I am trying to increase motion blur subdivs, but each 4 additional subdivs in motion blur mean another 100% of rendertime. So 16 MB subdivs already means 400% growth from original rendertime, let alone that i need at least 40 MB subdivs to get something close to clean sundisk reflections. I have really no idea how to solve this.

Maybe would be best if you can get me the scene to vlado@chaosgroup.com and I'll see what can be done about it.

Best regards,
Vlado