View Full Version : newbie zbrush>lightwave question

11-10-2007, 04:52 AM
im trying to pick up the basice on zbrush now but im a little confused.

if i take a mesh and save it as a .obj. then bring it into zbrush and ONLY divide the mesh, do no sculpting at all, then bring the divide level back down to one and export it. when i open it back up in lightwave the model seems to have "softened". i loose a lot of the detail i had made with the original polys.

i would love to know if this is normal or if im doing something wrong?

before zbrush


its not a huge difference, but things definitly become "softer"

11-10-2007, 11:18 AM
Could be it's just that ZB has smoothed it out as part of the subdivide process, but kept it smoothed even after taken back down. Could be a bug, but might be something ZB needs to do. I don't know.
Did the original model have any triangles in it? If so, ZB may have converted them to quads, since it "likes" quads better. I think they say a model should be only quads, and have no triangles in it. Or maybe it's don't mix them, I can't remember. I seem to remember seeing in a video that sharper edges need to be softened, like through edge beveling, before importing to ZB, for this very reason. I would think though that if no changes were actually made, it should export the mesh as it was originally.

One thing about ZB and LW that's real important - if you set up object groups in a LW model adn then export to ZB and back again, your groups will be gone. Poly groups, but not point selection sets. An important thing to remember.
Also, ZB is designed primarily as an exporter of displacement and normal maps for various 3D apps to use at render time. Any significant amount of subdividing and sculpting is going to create OBJ meshes so numerous in polygons that most programs won't be able to deal with them.

I hope you still have the original mesh. If not, you could probably use ZB to get it back to its original state with some sculpting at a not-too-high level.

11-10-2007, 11:56 AM
Just to add to that, ZB will "lose" all the materials you might have assigned in LW when it exports an OBJ, replacing all materials with one, called Default_mat, or something similar.
UV maps stay intact, though.

11-10-2007, 02:08 PM
hmmm... it is all quads, and i hadnt set up any groups or any materials yet =/. im gonna tinker with it some more today

11-10-2007, 02:27 PM
Well I just threw in the groups and materials part so you would know about it. it caught me by surprise, and I was none too happy about it. ;)
That wouldn't have anything to do with your issue though.
Try to soften up some of those harder angles in LW first before exporting and see if that helps.
I do have to say though I'm not sure why you want to export and re-import with no changes. You could probably bump it up to level two, do some sculpting on it, export it and end up with something you're happier with anyway.

11-10-2007, 02:35 PM
If you subdivided it once (in ZB), it likely should look softer than the original poly mesh?
A Subdivision level 1, is still using SubDivision Ummmm Once.... :)

11-10-2007, 02:38 PM
If you subdivided it once (in ZB), it likely should look softer than the original poly mesh?
A Subdivision level 1, is still using SubDivision Ummmm Once.... :)

That's funny, I missed that entirely. Fort some reason I read that as having been taken back down to the original level of 0. Oops. :foreheads

11-10-2007, 02:42 PM
That's funny, I missed that entirely. Fort some reason I read that as having been taken back down to the original level of 0. Oops. :foreheads

Heheh, I thought i must of missed something in the OPs's post, so i read it 3 times as to why you didn't mention it to him, Because i know you know that stuff with Zb... :)

11-10-2007, 02:51 PM
hmm good catch.

when i bring the obj into zbrush with no divides the divide slider is greyed out. if i divide once, the slider says 2. at lvl 1 i have the same amount of polys as when i imported. is this default? it appears that level 2 is the first lvl that actually adds geo to the model. if i divide once than slide back to the lowest level the mesh has already been softened =/.

11-10-2007, 03:21 PM
That *is* strange.
I was curious so I just whipped up this simple "stick" figure and exported it from LW as OBJ, imported it into ZB, raised the level once with CTRL+D, put it back down with Shift+D, exported as OBJ, loaded back into LW...
The polygon count is identical - 353 polys in both models. the one on the left is the original, the one on the right is the ZB export. There is no smoothing on either, but clearly they look different.
I've never noticed this before, because I've never used ZB in this way.

BTW, exporting from LW into ZB and back out again without making any changes, results in a model that looks identical in LW to the original.
Well, good - I needed a mystery today. Gonna have to figure this out now. ;)

11-10-2007, 03:28 PM
Wait... ZB has literally rounded out some of the polys. Not added any additional ones, but moved the edges, which you can see in this shot.
I think that's just normal ZB behavior. As I said earlier, I remember hearing someone in a video saying you have to make your mesh in a way that ZB doesn't smooth it out too much. Since I usually do that anyway, I wouldn't have noticed this.

11-10-2007, 03:31 PM
Man, I'm having some serious attention deficit today. I should have noticed that difference the first time around. ;)

11-10-2007, 03:48 PM
ahh good to know its not just on mine. anyways its moot i guess, after i applied the displacement/normal maps in layout the detail is returned. thanks for helping out IMI =)

11-10-2007, 03:54 PM
No problem. If you need any more help, just yell. That's a pretty cool looking model you have going there, btw. :)

11-10-2007, 05:40 PM
I've never used a model saved from ZBrush. I make my UVs in Silo. I paint my displacements in ZBrush and load the displacement map and apply it to the .lwo

11-11-2007, 12:51 PM
It seems close to the result in modeler if you set your subpatch divisions to 1 and then freeze the mesh, it just smooths things out without dividing the results