vraydisplacement texture issue

[Crayox13]

Hi guys,
I have to solve this issue this time, I keep skipping it on all my project.
So recently I made a simple black and white texture for an octagonal stone floor. Using 2d mapping is no good for this, but 3D mapping gave me excellent quality, very sharp stone edges, etc...even with Max subdivs 10. I set the edge lenght to 1.

Now the problem is with my stones texture. I have these awesome stone textures from Arroway 8000x6000 pixels or something, and when I render them I don't get any detail at all. As if someone blurred them out. If I turn off max bitmap texture filtering I get some detail but very strange, nothing like the texture, it looks like someone bad hair do. I also tried using vray bitmap tex, the same.
Shouldn't I be getting awesome stone shapes with textures like these!? I mean that simple black and white gave me great details so...

thanks in advance!

[svetlozar.draganov]

Hello there,

Could you please send this example along with the textures to vray@chaosgroup.com
Thanks in advance.

[windowlicker]

Are you using Real World Scale? It does not work with 2D displacement.

[Crayox13]

No...but I'm using 3d mapping.

[JohnVK]

I also have one set of the Arroway textures, the Stone Vol. 1, and I must say, they are mostly not suited for displacement.

Each texture has a diffuse, bump and specular bitmap file and you would typically use the bump version to pipe into the displacement modifier. However, I suspect these bump versions are (pretty much) straight conversions from the diffuse version. That means they contain a LOT of high frequency noise which will lead to spikes in the displacement especially once you set a too high displace value. I have found that 1cm is already way too much and will most definitely produce spikes with these textures.

I'm guessing you are running into the same problems I have (had).

Now you can kind of combat those spikes by adding blur to the bump bitmap map you're using in the VRayDisplacementMod or by using filtering through the VRayDisplacementMod but I have mostly not been able to get rid of them all myself.

In most cases it's best to create your own customized displacement texture in PhotoShop using the diffuse or bump textures of Arroway as a starting point. Then filter out all high frequency noise and equalize the gray values to a point where it would work properly for displacement.

So for straight bump usage they are fine. Not so for displacement I'm afraid.

[Crayox13]

I see....Svetlozar said that too.
I'll try to blur the maps in PS.

thanks

[Crayox13]

Hm...is it normal for displacement (with only 10 subdivs) to increase render time like 5 times at least? My IR is not done (-3, -2) after 2 hours

[flino2004]

Did you set gamma for the displacement at 1.0? I also change the diffuse blur filter very low.

[Crayox13]

Cool, haven't thought of that. It's less spiky as I see, when I set gamma to 1.0.
I'm doing some tests now.

One thing that is strange is that subdivs only affect render time, I tried 1, 10, and 150, and every time the object looks the same. Is that normal?

Also, I tried both with and without "view-dependent".