Thanks for the ideas.
What do you mean by āborder edgesā? The plugin should crease the edges of any groups defined in the OBJ as smoothing groups. (It can fail if there are polys with >4 verts, as thereāll be a mismatch between what the plugin sees and what ZBrush loads.)
(I forgot to mention, if you can send me the tank obj Iāll take a look to see whatās going wrong.)
dustbin1_uk,
Your pebble obj has a smoothing group that the plugin recognizes but as there is only one no creasing is applied. The plugin needs at least two smoothing groups so that there are edges to crease.
Edit: Hereās a version of your pebble with two smoothing groups. If you load it into ZBrush using the plugin youāll see that if you divide a few times a crease is maintained around the pebble.
AH! now edge creasing is something blender does, but through modifier stacks (kind of tempory effects on a model, maya probably has the same), but get it to an obj?
In Blender we create a modifier, say a subsurf, that subdivides the mesh, then we can add a crease to an edge to prevent the smoothing effect from that subdividing. We can also add a smooth modifier and crease edges there too.
But, I have no idea if we can export that to multi smoothing groups in the OBJ.
Leave it with me to experiment and surf the web for answers and Iāll get back to you Marcus.
I dont have my files with me right now, but I can explain the border edges things.
First i must explain, i dont REALLY understand what āsmoothing groupsā are, but I suspect thatās where the problem lies. In maya, itās just a case of selecting edges and selecting āhardā or āsoftā, theres no actual mention of groups.
Anyway, hereās my problem, Iām doing low poly work, so things like hydraulic hoses, i delete the end caps, so the hoses are basically open at the end. these edges are what i mean by border edges. If I āhardenā these edges, take them into zbruh with your plug, they get no treatment, and on smoothing the hoses essentially pull back from the end.
to get around it i either need to fill in the end caps or add extra edge loops to hold the smoothing process back.
Like i said, i dont understand smoothing āgroupsā, so maybe itās because theyāre border edges, they dont have connected faces to contain the opposing smoothing groupā¦ I really dont know, youāre the genious 
As far as my tank obj, it IS a problem, BUT, it forced my to split my tank into logical groups (turret, tread, vents, etc) and import them as sub tools, and itās actually giving me a good degree of flexibility, so I learned something new For curiosities sake though Iāll send you the obj in the morning.
Seriously, I owe you such a debt of gratitude, itās an awesome plugin in general, but this specific tank project iām building in a style that otherwise would have been close to impossible. 
exporting my whole tank is now magically working :rolleyes: i guess maya was just having a bad day yesterday lol, the problem doesnt seem to be cropping up again.
But right now iāve come across one REAL problem.
Iām working on a vent (attached obj) and in Maya i can freely import and export the obj and all of my soft/hard edges stay correct.
However when I try import this into zBrush with your plugin, MOST if it is fine, but the corners of the square openings in the sides dont crease, and what should be nice square openings end up round.
Theres also some wierdness in the inset groove near the bottom that i cant really describeā¦
side_vent.zip (12.8 KB)
The problem is that you havenāt defined enough smoothing groups for ZBrush. Iām not that familiar with how Maya handles smoothing but the plugin works in basically the same way as creasing polygroups in ZBrush: a group is isolated and its edges are creased. So if you want a crisp crease at a corner you have to make sure you have at least two smoothing groups so that thereās a crease at the change in direction.
There are two things you can do:
Iāve added more groups to your model to keep the vents square (but I dare say the insides donāt smooth as you wish!).
ok, the file you just sent me does exactly what i wanted.
I have a sneaking suspicion the fault lies in the way maya takes its āsoft/hard edgeā approach and tries to export it into smoothing groups. As you said it clearly doesnt contain enough smoothing groups, but thats something maya doesnt give me any control over, whatever algorithm theyāve used to compute the groups clearly isnt up to snuff, because iāve found lots of little areas where this is happening in corners.
now im going to have to import all this geomtry into another program like 3ds max to fix it.
only this project needs to be done VERY soon. and ive never used another modelling app.
iām going to go cry for a littl while now.
Im curious, in zbrush ive never even heard of a way to select edges, but if you could make a plugin where you select a group of edge, click crease, and repeat, that would be the greatest plugin the world has ever seen. itās such a nightmare showing and hiding faces trying to isolate 1 edge. 59 times.
Thank you so much for taking a look at my file man, i really appreciate your time
Update 11/20/2008
This plugin is now available for ZBrush 3.1 PC and ZBrush 3.12 Mac. You can get it from the Download Center.
sweet osxāness 
thanks guys
The link for the PC version is broken. Are there actually any changes in this release? Or is this just adding MacOSX support?
Incidentally Iām still trucking through finishing the low poly tank and taking it into 3ds max to fix the smoothing groups, iāll post pics as soon as itās in zbrush
thank you .
is it possible to crease open edges?Because i found that open edges would run away after divided.How can i deal with it?
The link for PC is not working in the download center
For open edges, AFTER youāve imported and creased, with your whole model visibile, in the geometry rollout, click crease. voila
Thanks for the tip, dangermousenz. I look forward to seeing the tank when its done. We donāt get too many tanks posted at ZBC.
The PC link is working now. There are no updates in this version (apart from a small bug correction if you moved the button to your custom interface).
As promised
It took a bit longer than it should have, but Iāve never used 3DS, and Iāve never used zBrush for anything but squishing spheres for fun, so this has been a monumental learning curve.
Now itās time to actually sculpt and texture this thing!
Wow, thatās great! Post it in the main forum when youāre ready to, with a few words of how you did it. I think it will be popular.