VRayDirt + Output Map

[Art48]

Hi,

I noticed that for some reason I cannot color map the VRayDirt Map with an output map, to get sharp borders.
I've done it several times in the past with earlier versions but the output map color mapping curve doesnt seem to have any evvect on the AO.

[Macker]

You did it before? How? It's calculated at rendertime isn't it?

[Art48]

Yes definitely did it at around 2.4. Successfully. Multiple times.

[LudvikKoutny]

Yes definitely did it at around 2.4. Successfully. Multiple times.

I had same problem some time ago. It turned out to be caused by using Vray universal settings, or in general high number of max AA subdivisions. Basically, amount of Dirt subdivision is subdivided by amount of max AA subdivs. So if you have max AA subdivs set to 100, and only 16 subdivs in dirt map, then 16/100=0.16, which is less than 1 sample/pixel, and that results into impossibility of getting meaningful results. So you need to either crank up VrayDirt subdivs really high, or use lower Max. AA subdivs amount.

It may also be problem somewhere else though.

[Art48]

Thanks to your comment I re evaluated and I found the issue. It's indeed a bug with the progressive sampler. The Progresive sampler completely ignores it. The adaptive sampler does everything as expected

[Art48]

Can someone of you support guys confirm it is a bug?

[vlado]

Works fine for me. However for this to work properly, the VRayDirt map needs to take more than one AO sample per shading point, which generally means it should have high enough subdivs. Otherwise, if just a single AO sample is taken, it is either black or white and no amount of curves can change it to something else.

Best regards,
Vlado

[Art48]

It works for you using the progressive sampler? Strange. I got 128 subdivs in the map and when using progressive is there is not really such a thing as max subdivs right? I mean when I enter 100 in the max subdivs, it will PROGRESSIVELY advance to that level and not just divide all material samples by 100 right?

[vlado]

It works for you using the progressive sampler? Strange. I got 128 subdivs in the map and when using progressive is there is not really such a thing as max subdivs right? I mean when I enter 100 in the max subdivs, it will PROGRESSIVELY advance to that level and not just divide all material samples by 100 right?

It will still do the division. Alternatively you can use the min shading rate parameter, which will force the dirt map to take more samples per shade.

Best regards,
Vlado

[Art48]

Okay. What I don't get though is that in the adaptive sampler the max subdivs means that every pixel gets at max those value, if it reaches it, the renderer will stop there and continue with the next pixel no matter if noise thresh is reached or not. But you said in another thread that the progressive sampler stops if ANY ONE pixel in the image reaches the set subdivs (100 by default).
So if I enter 0 to let it render indefinitely, would that basically mean that shading subdivs dont get divided at all? I am confused. I cannot enter "normal" settings like 12 max subdivs since the render will just stop if any pixel reaches that subdivs.

[vlado]

So if I enter 0 to let it render indefinitely, would that basically mean that shading subdivs dont get divided at all?

No, it means that V-Ray will just use internally a very high value for the subdivs (something like 1000). For the next build of V-Ray, I'm adding some additional info boxes that tells how you each particular subdiv value in the scene is being sampled. Hopefully this will take some of the confusion away.

Best regards,
Vlado