Vray and Zbrush

Hi,

I’ve recently upgraded to Zbrush 2 which outputs displacement maps from hi-poly geometry - however when I use them with Vray I get banding on subtle areas, as if the map is 8bit even though it is a 16bit TIF.

I’m not sure whether this a Vray or Zbrush problem (Zeddicus has the same problem).

Has anyone here had success with Vray and Zbrush 2?

Thanks,

Steve

Hi Steve

Sory i have no idea to solve your problem. But a Question. I´ve seen some z-brush videos, with very impressing stuff. We are thinking of bying this package for finetuning our modelling and renderpipline. What is your opinnion of it. Our main application is max and Vray. Is it worth it, and

what is the workflow like. Could you tell a bit of your experiance especialy about the learning curve ?

that would be very gentle.

Thanks

Tom

www.lichtecht.de /com

I’ve just started learning Z-Brush but I have to say that they have some of the most forward thinking methods of cutting that learning curve down quite a bit. You should definitely download the demo and see for yourself. It will only take a few minutes to realize how easy it’s going to be to learn almost anything about it.

--Jon

Thanks for your comment J_Bug

ive just been on their website for this, and i also found a PDF with grate learning and tutorial stuff. a PDF that you can download after login.

seems to be a very intristing Program for finetuning your models. We will see .

Tom

All of the PDFs are nice too but the app has it’s own learning system that takes you step by step. I should have mentioned this earlier

--Jon

Hi,

it’s a very solid application, there are pdfs as well as Zscripts to take you through things.

Workflow is basically this.

Model in Max (or zspheres in Zbrush) as a low/medium detail model.

UV map if you prefer, or use Zbrushes internal mapping (though the maps are hard to edit in an external app if you do this)

Subdivide the mesh, start sculpting, subdivide etc.

At the highest level you can work with a 2D painting system (projection mapping) which is then applied to the 3D model (you can use custom brushes in this mode)

Generate displacement and/or normal maps.

Export your original low poly model if it’s been UVMapped in Zbrush.

Import into Max and add a VrayDisp Modifier and the 16bit Tiff displacement map.

It can be a little unusual compared to standard window apps, but it’s definitely worth persevering with.

- Steve

Hi Steve,
Have you tried converting your map to a BMP or TGA? When you say 16bit are you talking per channel or in total (millions of colorsa)? I’m not far enough along to test what your describing but if you’re talking about millions of colors then you could try 24bit (true color).
--Jon

Hi,

it’s 16bits per channel for grayscale displacement maps, and 8bits per channel for normal maps.

Cheers,

Steve

there is a workflow written in the “practival manual” if u havn’t seen yet, check it out. Step by step instrucyions are there.

hi there,

i´ve written a post about that displacement "problem"sometime ago

http://www.chaoticdimension.com/forums/phpBB2/viewtopic.php?t=4102&highlight=

maybe this will help you a bit
cheers

Interesting idea about using an HDR map instead of an LDR one. Might be worth a try I suppose. I still think it might be something Zbrush is doing to the physical mesh itself everytime you press the divide button and is just getting translated into the map it generates. Could be wrong though as those images were good evidence that Vray can do strange things as well. Even so, I still think Vray is a superior displacement renderer.

By the way, why do all the threads in this forum always come to an abrupt halt with no conclusion/solutions? Seems to be a frequent trend here, and is highly annoying lol.

PS: Just thought of trying something. Why not take the generated alpha map in Zbrush and apply it to the model as a texture? Then you could paint out any distortions. Oh wait… maybe not. Can Zbrush apply 16-bit maps as textures or only 8-bit? Maybe this idea would work with another texturing program (Deep Paint, Bodypaint, etc)? Sorry, thinking as I go here…

By the way, why do all the threads in this forum always come to an abrupt halt with no conclusion/solutions? Seems to be a frequent trend here, and is highly annoying lol
Hehe, I was wondering the same thing.

Well, first things first. I noticed that if you export the displacement maps from the texture dialog no matter the file type you get an 8 bit texture and a bigger file size… If you export from the alpha dialog you get 16 bit maps and smaller file sizes. So my question is how are you exporting your maps out of Z?

By the way, why do all the threads in this forum always come to an abrupt halt with no conclusion/solutions? Seems to be a frequent trend here, and is highly annoying lol.

What an overstatement :!:

The maps are being exported from the Alpha panel, and Max says they are 16bit. I seem to get better results when using a negative RGB offset in the bitmap rather than using the offset in the displacement modifier.

- Steve

Try playing with the blur and blur offset parameters of the bitmap. Make sure Filter map is on in VRayDisplacementMod.

Best regards,
Vlado

Hi Vlado,

thanks I’ll give that a go - wouldn’t it give artifacts along UV seams though?

Thanks,

Steve

Arg… I’ve found the same problem. The only solution I’ve come accross is to use very low quality displacement and a normal/bump map for details(a poor solution because low quality displacement can result in similar artifacts). The free plugin Gnormal lets you use normal maps in the bump slot and works very well, but only works for max 5…

Quick FYI regarding gNormal: I believe there is now a beta version available for Max 6. Haven’t tried it yet though.

Hey, Vlado was right! A little bit of blur offset (about 0.008 works for me) and summed area filtering works very well. Oh, and it’s good to see that gnormal has been updated, especially useful if you need to blur the displacement map.
Though Steve_Green is right, blurring the displacement map will give you artifacts in UV seams.

testing this yesterday i noticed i got banding on 3d mode, but none on 2d mode.

i have one theory that maybe vlado can answer and confirm or reject it. could max be clamping the map to 8 bit? a while back i was using simbiont and found out that it was clamping colours before rendertime(they have since fixed this). i wonder if vray, or max, might be doing the same? maybe there is a glitch somewhere in the 3d displace code clamping this? i get the same banding in mental ray.

any help would be appreciated

later