ZBrushCentral

Problems exporting with UVs

ZBrush Usage Questions
#1

Hey all,

I’m having troubles when exporting my mesh from ZBrush with UVs (originally from 3ds Max) for use with xNormal. It seems that ZBrush breaks the UVs up into small tiles and consequently I can’t get a correct direction map from xNormal, its not readable by mental ray when I take the mesh back into 3ds Max for rendering.

As far as I know, the direction (aka Vector) map itself should have a smooth range of colour, similar to a normal map but the result I get is divided into these little squares as a result of the way ZBrush exports its UVs.

Strangely I have not had this problem with generating normal maps in xNormal. If anyone has had experience in a similar workflow from Zbrush to xNormal for maps (specifically direction/vector) and then back to Max for animation and rendering please throw in your two cents.

Cheers.

#2

Here’s hoping that Z4R2 will be able to generate VDMs. Wouldn’t it be great?

#3

i’ve never had that problem from max’s unwrap. are you sure your not replacing the uvw by auto-unwrapping in zbrush? even with the auto-unwrap guv tiles from zbrush i haven’t had that problem once it came back into max.

humm. are you using goZ or are you manually exporting the normal map?
if manual it might just need to be fliped 180 in the U in the max bitmap window.

just trying to cover the obvious bases here.

sometimes the uvw’s from max do do corrupt. a student of mine lost a file at the last moment, but you could see strange lines down the normal and texture not what you’re talking about.

my last thought is that you have overlapping poly’s inside your uvw - that could certainly cause zbrush to flipout.

good luck

#4

Hey magbhitu, thanks for your reply.

Im positive that the UVs I’m exporting are the same ones I generated in Max, I recognize the shape and placement of the seams.

I did actually use GoZ to transfer these UVs to my model in ZBrush from Max, so thats not it. I suppose I could try doing it manually but I think its the same process in the end.

I am certain that it’s a problem with ZBrush because I have tried exporting (to OBJ format) directly from Max with the identical UV layout and the result in xNormal is what looks like a correct vector displacement map (without the divided squares I mentioned earlier).

There must be something I’m missing in the process here…

Anyone?

#5

my suggestion is do a quick unfold unwrap of a box in max and see if it does the same thing in Z

then you know whether it’s your file or something that’s happening in zbrush

#6

Yep, I have tried with several different objects, same deal. Exporting from Max to xNormal results in a very different map when compared with the same mesh with the same UVs exported from ZBrush.

#7

well then could it just be the normal map settings in zbrush. i’m not surprised there are different results between xnorm and zbrush. do you remember the old 3.2 era normal maker in zbrush. it had a lot more setting, as i’m sure xnorm does.

i don’t know if i can help but seems like the next step is for you to post screenshots of your settings and the results so that folks can weigh in.

#8

Thanks again magbhitu,

I wasn’t into ZBrush until release 4 so can’t really comment on that one. I will render some images to post here soon and hopefully clarify my situation.

Cheers.

#9

Ok, for anyone following this thread here’s a direction (vector) map rendered in xNormal. The mesh was something i quickly made in Zbrush with UVs done in Max using GoZ, back into ZB and then exported for use with xNormal. Notice the square shaped tiles populating the map. AFAIK, a valid VDM should look smooth. Also, see the second image, a mental ray render of this map applied to the lower poly mesh. I apologize for the crudeness of the images, but this should give you an idea of what im dealing with. Any thoughts would be appreciated. Thanks in advance.
faceted_vdm.jpg

Attachments

faceted_render.jpg

#10

Many looking at this may say it must be because mrg isn’t on when importing back into ZB using GoZ, but no I definately have that covered. I have tried cycling the UVs also.