Yesterday I saved it and it was fine. I opened it today and the polygroups came out like the image. This is the second time. I fixed it after the first. Anyone know why this is happening?
Thx,
- Dave
Make your polygroups at lowest subdivision level. This happens if you make them at a high level of subD then switch to a lower one.
Thx for the reply.
I just did a quick test of that method and it gave about the same results. Going to lower SubD levels is making blocky selections to begin with.
Hmm. Are you using any features that would similarly distort or alter topology, like Dynamic Subdivision?
Perhaps you could give me a rundown of what you’re doing, and what features you’re using.
Does this happen with any mesh, or just the mesh you’re currently working on with whatever process?
[edit] I want to make sure we’re clear on my first point though. Polygrouping can only be assigned by the polygon, so if the selection includes a blocky clump of low subD polygons not cleanly separated by an edge loop, it will be blocky. The point is, that if you assign polygroups at the lowest level of subD, they will keep that selection at high subD, but if you make them at a higher level, that border will shift when you drop to a lower level.
That’s why it can sometimes be difficult to assign clean border polygroups with brush masking, as the falloff makes it imprecise. You may need to either use ZModeler to assign polygroups polygon by polygon, or marquee/lasso selection tohide polygonsfor more precise grouping. You can get clean border polygroups with brush masking on a fairly high poly mesh like yours, but it may require using the “Group masked” feature with a high smoothing value, which will alter topology.
This is one of the reasons people frequently use Zremesher to establish a new, low poly subD level for high poly meshes. Certain things, like polygrouping, are just easier to do at low poly.
I’m afraid I mangled my reply pretty badly here. Be sure to see my ninja edit above to make sure we’re both clear on the polygrouping situation.
I haven’t used Dynamic Subdivision or anything like that. But what I did do at one point in time was added PUVTiles as a temporary UV set so i could save my mask (which gave me a blocky result when I went to reapply it cause of the nature of PUVTiles).
When Polygrouping gave me a blocky result after reopening it the next day, I thought it might have something to do with it. So I deleted the Temp UV set and repolygrouped it from Masking again. As far as having this problem with other Meshes I’ve been gone from ZB for a long time.
I like extreme realism, Avatar, Jurassic Park, Motion Picture kinda stuff. Trying to do that with that old System I had was nothing but complete frustration. So now that I just did my first PC build, I have A system that hopefully can accomplish what I’m wanting to do.
P.S. I did alot of “marquee/lasso selection tohide polygonsfor more precise grouping” And it was all done by mask brush.
Ok, there are two separate issues here, and Im afraid we may still not be clear on one or the other. This is partly my fault for not being clearer. Please bear with me, but I have to make sure we are on the same page before moving on.
- Polygroups must be made at lowest level of subdivision. If you make them at the higher level of subdivision, you’re likely to make a rough border selection that cant be seen at high SubD. This border will visibly shift when switching to a lower subD level, and will remain shifted even when you switch back to the higher. You must make your polygroups at the lowest available subD level, with clean edge selections, and then they will maintain that border when switching to a higher subD level. See illustration below:
- Polygroups are limited by topology. In order for a polygroup to have a clean, crisp border, it must flow that way in the geometry. So when defining a polygroup, it is best to select polygons that are cleanly separated by edge loops.
In your first response to my original post, you demonstrated that polygroups were still blocky while using a hand brushed mask selection at low poly. This is normal. Hand brushing your selection is likely to select a haphazard clump of polygons, which will result in a “blocky” border. If the topology doesn’t accommodate the shape you want to make, you will have to change the topology, for example with the Tool > Polygroup> Group Masked function with a polish value assigned, or with the slice brush. Otherwise you need to take care to only select polygons that form a clean border. See illustration below (the final image shows off group by masked with polish):
If you think we’re on the same page on both of those points, and neither one explains your issue, we can move on.
Thx for all your responses,
I didn’t realize they would lose their shape when stepping down then back up again in SubD’s. I guess I’ll just have to work with it the way it is.
Thx again for the help.
-Dave
It’s because the polygons you select at the highest subD level may not cleanly subdivde back down into a lower level, and so Zbrush has to make an approximation. You avoid this by making your polygroups at the lowest level, as then they will always subdivide up and down perfectly. Not to mention it’s simply much easier to isolate individual polygons at low subD.
Part of the issue I see with what you’re doing, is that you’re trying to make, for instance, the horns on your creature a separate polygroup, but the topology of those horns doesn’t support a clean border at the point you’re trying to make them. You need to drop to the lowest available subD level, and select only the polygons that all stop at a common border–typically an edge loop. You wont be able to do this with hand brushing–it isnt precise enough. Zmodeler has a function where you can assign polygroups by simply clicking on individual polygons, but this only works well with fairly low poly meshes. Lasso selection and hiding with the “group visible” function is probably the only way you’re going to be able to do that.
If you want to hand paint your polygroups and have clean borders, you need to do that with one of the functions that alters topology, like the polish feature I mentioned above, or one of the group loops/panel loops function in the Tool > geometry > Edge loops menu. This will change your topology to give you a clean edge along your painted selection, although anything that alters topology is going to complicate multiple subdivision levels. You may need to construct an entirely new low poly mesh with Zremesher, in order to reconstruct the topology, and transfer the high poly detail from the original model.
Ok thx, I’ll look into it.
just stumbled about this problem as well. Not sure if the explanation makes too much sense, Polypaint Data can also be applied at different SubDs without Problems… so why not PolyGroups?