Hi Zeddicus,
I’ve got a couple of questions about your workflow using Vray’s displacement in Max.
First, why 3D rather than 2D? I thought 3D was more for procedural maps rather than displacing bitmaps. However I can’t get anything at all resembling the original zbrush model using 2D.
3D also seems to need cranking up to something like 800 to get any distinct displacement (and then it is very grainy)
I also get seams along the UV borders - have you noticed this at all?
Thanks,
I was trying out a disp map on an old head model:- 
When using the vray disp modifier’s 3d option, moire/banding occurs:
with 2d selected, however, there is no banding, but other artifacts seem to be more common (splits in the mesh, mainly).
Earlier today I’d been zbrushing the same model and no banding had appeared. Just a hunch, but I think the trigger for the banding occurs at export time from zbrush, and is something to do with the morph target-switch workflow.
Stephen: One thing you might want to check is the scale. Models too big seem to require high settings to see anything sometimes, and models too small can cause even conservative settings to be too much. Maps exported from Zbrush need to be flipped vertically to display properly. Regarding 2D vs 3D setting, I’ll just use whatever renders best, lol. And yes, I see artifacts with UV borders occasionally as well. Sometimes you just have to muck around in Zbrush and Max until it comes out useable (yeah, I seem to be relying on luck a lot lately I think).
brushoid: Yep, that’s the banding I was talking about in the other forum here. I’ve found using the 2D setting in Vray can help too. I’ve also found artifacts can be somewhat controlled by playing with the resolution setting (up and down as well even). First I think it’s one thing, then another. Sometimes it happens, sometimes it doesn’t. I’m just not sure of anything anymore and all my testing, besides becoming a tad monotonous, is really making my head hurt, lol. I do know one things though. The banding is definitely there in the maps that Zbrush generates, even when using the highest poly count possible.
PS: 2d settings in vray rendered in 23 seconds, 3d setting rendered in 31 minutes.
Big disparity in render-time, but very little in final image quality (2d comes out on top because there is no banding).
zeddicus:I’ve also found that sometimes the banding happens, sometimes not. I think it is something to do with the morph target not matching the initial model. However, the disp map looks OK to me in PShop.
When I tried to re-import the .obj model at subdiv level 1 I got an error saying that the two models differed in vertex count. Visually, subdiv level 1 and the initial .obj model look the same.
Does anybody have any idea why the morph target and initial imported mesh would differ?
Zeddicus,
thanks, I’ll check the scale (I think I left the obj exporter importer set to 1.0)
Regarding the seams, Kaldera (texture/normal/displacement baking plugin) has a setting for ‘skirts’ which is where it repeats pixels along the UV borders, maybe there’s something similar in Zbrush?
Maybe the full manual/pdf might fill in the blanks, or maybe any beta-testers who were using Max/Vray might like to give some pointers as to what could cause the artifacts?
Thanks,
<BLOCKQUOTE>quote:</font><HR>Maybe the full manual/pdf might fill in the blanks, or maybe any beta-testers who were using Max/Vray might like to give some pointers as to what could cause the artifacts?<HR></BLOCKQUOTE>
I’m hoping to hear something from the more advanced beta users of Zbrush as well. So far the Lightwave/Max/Maya/etc users out there been surprisingly quiet. I find it strange too, since one of the big advertising points of Zbrush 2.0 was it’s ability to be used in a real production workflow (example: the big deal with WETA using Zbrush) as well as it displacement generation abilities. Becuase of this you would think that this is an area that had been thoroughly tested and well documented. Hopefully the manual, when it comes out, will have some pointers that might help avoid the banding problem.
Maya users doesn’t seems to have any problem at all using displace and maya renderer or mental ray
in max i have the same problem as you
first the scaling-> which one is good -> no idea
export from Zb, -> seems to rprrefer tiff or psd not bmp
and for the uv mobving someone has used the cage function (personnaly it changes my object appaerance and as i using Gutile of Zbrsuh it’s a problem
well, united we trust 
:rolleyes:
I have a MAx to Vray tutorial that will be out in a day or so that outlines a few pointers to keep in mind when travelling between the two apps. Also,on of my collegues here at work is just finishing up a Zbrush script and max script that reads the positive and negative value of your displacement map in zbrush, then impiments those values in max by adding the vray displacement and setting the vlues…AUTOMATICALLY. Just press a few buttons and you’re away. I’m sure he’ll post it when he’s ready.
Glenn
Sounds intriguing. I look forward to reading it. In the beginning, when Z2 first came out, I was considering making a Max-to-Zbrush-to-Max displacement tutorial as well (for both MR and Vray), but unfortunately dropped the idea when I ran into the banding problem and there seemed to be no solution forthcoming. Regardless, I’m glad to see someone else has the ball well in hand. 
Hi,
Is there someone who could explain the exactly way to make this thing (displacement map with 3d model imported from Max)
I found several tutorials for Maya, and tried to translate them to Max but it doesn’t work so well.
I’m working with Max for the lowres model, Zbrush2 off course for displacement, and Max for rendering with Vray.
I’ll be glad to have a nice an efficient way to succeed my hoping result.
thanks a lot.
Hi Zeddicus,
I dont know Max very well but the “banding”
problem that you are seeing looks like
something that happens when you use 8bit maps in a MicroPoly Displacement renderer.
Ive seen this before ( in Mental Ray and PRman ) when we use 8 bit maps. Try to render the maps using 16 bit color space.
With 16 bit there are enough color values
to hide any banding.
Ive been working at Weta for the past few
years and I can tell you that Zbrush does
work well in a production pipe. But like I said
before I dont know Max but to solve your
problem I think you should start by tring
to figure out how to import and render 16 bit color maps (if you rendering the micro poly displacements). Displacements do work well with 8bit color but if you have very soft forms expressed in the maps, you are more
likely to see this banding problem.
Id be curious to know if your rendering with
8bit maps.
Dave
<BLOCKQUOTE>quote:</font><HR>Id be curious to know if your rendering with 8bit maps.<HR></BLOCKQUOTE>
I’m generating 16-bit grayscale TIF maps and using those in Vray. It’s definitely something Zbrush is doing because I’ve taken the maps into Photoshop for closer scrutiny and I can see the banding in them (have to use non-tiled UV’s to see it best). I’m back to thinking it has something to do with the way Zbrush subdivides the mesh each time since that seems the most logical. Each subdivide is generating anomolies in the topology of the mesh and these are getting translated into the displacement map when generated. Seems to be hit or miss though; sometimes it does it, sometimes it doesn’t. Haven’t been able to figure out exactly what circumstances cause it to happen though.
Zeddicus, Try the following: Save the disp map in ZBrush as .psd. Open it in photoshop and save it as tiff. Don’t ask me why, but works for me!! The Banding is gone!
<BLOCKQUOTE>quote:</font><HR>Save the disp map in ZBrush as .psd. Open it in photoshop and save it as tiff.<HR></BLOCKQUOTE>
Gave your recommendation a try, but didn’t work unfortunately.
Here is a super simple test anyone can do. All you need is Zbrush and Photoshop (or any graphics program that lets you load 16-bit grayscale files).
See the banding? Look closely, it’s there as horizontal lines that are parallel.
As far as I can tell the best way to get the best results and minimal banding is to use the level 1 cage model for your base model in another package. IMO that’s one big drawback. That means I need to have 100% of the modeling done before I can hand it off to the rigger.
Skycastle, just out of curiosity, could you explain your zBrush workflow at weta?
I have a silly question.
Is your monitor set to display “true color”.
Also have you rendered the maps out as
displacements or bump?
I am awear that you can have banding is the
diff between your loRes and high on one vertex in the mesh is very extreme??
Can you post a map so we can see it?
I have a silly question.
Is your monitor set to display “true color”.
Yes, and even if it was 16bit the displacements wouldn’t show the banding unless it was in the map itself.
Also have you rendered the maps out as
displacements or bump?
If what you mean by bump a normal map, then I’m just using the displacement feature. I didn’t want to waste my time with normal maps until I get these issues out of the way.
I am awear that you can have banding is the diff between your loRes and high on one vertex in the mesh is very extreme??
Does not compute
Can you post a map so we can see it?
How about this?
The reason you are seeing banding in photoshop may be because even if you can open and edit a 16 bit grayscale image your graphics card still displays it at 8 bits unless you have 64 bit color but im not sure.
I think I remember reading somewhere on the vray forum that the banding is caused by a limitation in the 3d mapping algorithm. I do not get the banding with 2d mapping but always with 3d.
I agree, the 2D setting is definitely better than 3D as far as the Vray modifier goes. At least from my bit of on and off testing anyways. With 2D the banding can usually only be seen on the actual displaced areas. With 3D the stairstepping can be seen happening over the entire model. Regardless, in either case it only happens sometimes and pinning down the type of model and exact circumstances under which it does and does not happen, and whether it is Zbrush or Vray causing it (probably both), is the real issue that no one seems to be able to answer. I’ve pretty much given up for now.
I was pretty excited about displacement mapping ever since I read about it in summer of 2003, but I think perhaps it still needs a bit more work among other things (Game assest creation is another good thread for example). I was also excited that Zbrush was going to be coming out from the shadows to be considered for once a serious tool that could be used in a pro oriented production role. After all, it’s an awesome tool that deserves to finally be taken seriously by the industry. And while it seems to have hit fairly close to the mark with the recent release of Zbrush 2.0, my feeling is that it is still not quite “there” yet (please don’t get angry at me everybody, it’s just the way I feel sadly enough).
<BLOCKQUOTE>quote:</font><HR> Regardless, in either case it only happens sometimes <HR></BLOCKQUOTE>
Mine does it with every model. What I did notice is that it’s more visible in the displaced render depending on how you set your scene up. Whether you used an exported mesh with cage turned on and so on.