i was surprised to see there’s nothing in the FAQ to explain how zsphere’s work. Here’s my attempt:
Each sphere represents a cube. when you skin using adaptive skinning, zbrush looks at each cube, works out which side of that cube is facing its parent, and joins those 2 closest sides with a poly extrude.
[[attach=19714]fig1.jpg[/attach]]
this is why you get overlapping problems with things like hands. think about it; all the finger cubes are pointing towards the same top face in the palm cube of the hand, so they all join to the same face, causing ugly results.
[[attach=19715]fig2.jpg[/attach]]
the way zbrush gets around these problems is to subdivde the palm cube. This means there’s more individual faces along the top of the palm for each finger cube to attach to, so no overlaps.
[[attach=19716]fig3.jpg[/attach]]
this is what the x/y/z-res buttons do, tell the cube how many times to divide in x/y/z to give you enough faces. You can also use the ‘ires’ slider for a more automated result. Its default value is 6, which means ‘as soon as a zsphere has more than 6 children, subdivide it’. So for a hand, you would need this value to be 5, because you have 5 finger children from the palm.
You can be even more precice though. By default zbrush will subdivide cubes equally, giving you a 3x3x3 layout. But you can set these divisions to whatever you like, so the palm cube might have 4 divisions across for the fingers, and 2 down for the thumb (so there’s a gap between the fingers and the thumb):
[[attach=19717]fig4.jpg[/attach]]
The easiest way to achieve this is using one of the handy zcripts available, like zifedit or zifclick. Personally I prefer zif edit b because it doesn’t block the rest of zbrush when its active, but see what you think:
[http://www.zbrushcentral.com/zbc/showthread.php?t=8924](http://www.zbrushcentral.com/zbc/showthread.php?t=8924)
Finally, i find it helps to set the preview mesh density to 1 when layout out the sphers. This way you really see the cubes for what they are, much easier to sort out overlaps and twisting errors this way.
-matt