Breaking up a large mesh in Zbrush
polycounter lvl 18
Any tips on breaking up large meshes in Zbrush?
Previously I'd have imported a mesh as subtools for garments, head, armour etc, but my domwar sculpt is one large organic blob sitting at around 3million polygons. Since the texture sizes are 2048 I might as well eventually subdivide it again to about 12 million - but that's going to be one HUGE tool.
My approach was to mask off the legs/underside and extract that to a subtool, then invert the mask and do the same for the upper, but I lost all the lower levels. I think I can do this again at a lower level, subdivide it and reproject.
Might it be better to export a low level, map it to make uvgroups and reimport?
Previously I'd have imported a mesh as subtools for garments, head, armour etc, but my domwar sculpt is one large organic blob sitting at around 3million polygons. Since the texture sizes are 2048 I might as well eventually subdivide it again to about 12 million - but that's going to be one HUGE tool.
My approach was to mask off the legs/underside and extract that to a subtool, then invert the mask and do the same for the upper, but I lost all the lower levels. I think I can do this again at a lower level, subdivide it and reproject.
Might it be better to export a low level, map it to make uvgroups and reimport?
Replies
Usually I'll divide the mesh up at the lowest level using polygroups, then hide the groups you want to split from what is visible (at lowest subdivision level) and then split them.
Exporting the lowest level, UVing it so that each piece you want as a subtool is on a different UV square, reimporting back into ZBrush and then splitting the lowest subdiv level into polygroups and breaking them into Subtools is what you're after. If you crease the edges of each subtool you wont get any gaps when you increase the subdivision levels and the mesh contracts slightly.
Go to lowest level, hide all but what you want and make the remainder it's own polygroup
Go to the highest subd level
Delete lower subdivision levels
Delete Hidden
Reconsctruct subdivison levels
You can only 'delete hidden' on the lowest level, If you delete from the lowest level for some reason zbrush tends to lose some detail on the higher levels. This is why you go to the highest level and delete the lower levels, so then you can delete the geometry there and keep all the detail.
By going to the lowest level and hiding polys you don't want (and creating the polygroup to make selecting it easier) you ensure you have a clean mesh that can be reconstructed back down to that level. If you were to do this process on a higher level then zbrush won't be able to reconstruct down as far.
So you can then just save this as a new tool, load up the old one and repeate the process on a different part, save that, then append it to the other piece.
Ninjas = Subtools
I wish it was just a case of make polygroups, divide mesh and there you go, it's now all subtools with all your detail still in there.
After re-importing your UV'd meshes and setting up the polygroups for different UV areas you can go down to level 0 of your mesh and press the GRPSPLIT button inside the subtools pallette. This breaks the mesh up into subtools based on your polygroups and keeps all levels of subdivision intact.
Hours of frustrating reconstructing/ reprojecting/ smoothing ad infinitum saved!
I'd probably just do the polygrouping in zbrush though, hate having to import models back into zbrush hehe.
Yeah it depends on your workflow about which way to go about breaking your mesh up - getting a consistant, non-exploding mesh, back into ZBRUSH via MAX 2009 has been a painful process so I feel your pain on importing models back into ZBRUSH! I seem to have got all the bugs ironed out of the export process now though fingers crossed.
My base mesh human is already UVd and each chunk moved into its own UV square in MAX before bringing it into ZBRUSH so it's just a two click action to setup the polygroups and then break it up if you need to.