Subdivision Tool Causing Model to Disappear

[system]

Hello, my apologies if I’m doing this wrong. I’m new to zbrush, and the one error that has been plaguing me is that whenever I try to make more subdivisions in my obj model, parts of the model disappear. I’ve attached the before and after of dividing it once. Could someone please tell me what I’m doing wrong?

Attachments

[aurick]

Those are places where the edges aren’t welded. By default, dividing the model also smooths it. This causes unwelded edges to pull apart.

There are several ways around this:

• Weld overlapping points before importing into ZBrush.
  
• Press Tool>Geometry>Crease before dividing. This doesn’t weld the points but it does prevent the edges from contracting when dividing.
  
• Turn off Tool>Geometry>Smt before dividing. This adds polys without smoothing. Of course, that means you’ll still see the model as if it has few polys.
  
• Set Tool>Import>Weld to a higher value before importing. The higher the value, the less it’s necessary for the points to be identically placed – but also the increased likelihood that nearby points will be welded when you don’t want it.
  

By the way, ZBrush works best with quads. When you divide a quad it becomes four smaller quads and the surface is smoothed. When you divide a triangle it becomes three quads and the surface is not smoothed. If at all possible, you should convert your tris to quads before importing into ZBrush.