ZBrushCentral

Fundamentals of ZSphere Modelling.

I’m having some trouble understanding the way the tesselation works on ZSpheres. I’ve tried to read up as much as possible from the help files, tutorials, practical guide and this forum, but haven’t really come across anything thats explained really clearly how things work so that I can get a decent looking mesh to work with.

When I build with the ZSpheres I frequently wind up with overlapping geometry with edge loops crisscrossing through eachother and all sorts of horrible distortions.

So can anyone suggest something for me to read to really understand how these things work, and perhaps give a few pointers on getting a ZSpere model which is workable while I’ve got your attention?

I seem to have posted this in the wrong forum. Could I get a moderator to move it to the correct place, please.

Begin by reading the FAQ on ZSpheres here at ZBC, and also run the ZSpheres ZScript tutorial built into the Help system. Those will answer most of your questions very quickly and thoroughly.

hi jack

there are a few hand tutorials or zscripts I mean in the tutorials forum that will probably give you a really good idea of what you are missing…it sounds like you are missing how to control the rez of the zspheres…what a few of those with notes and actions turned on so you can see exactly what they are doing…and you will see what I am talking about.

Here’s another possible point of view…

It’s not you.

A couple of points to consider:

  • A lot of people create their lo res mesh in something else and then transfer it to zbrush.
  • A major feature in zb 2.5 will be a third alternative to mesh generation over zspheres.

Both of which indicate to me that unified skinning and adaptive skinning really don’t work in a lot of situations.

Just a thought.

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]]fig1.jpg

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]]fig2.jpg

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]]fig3.jpg

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]]fig4.jpg

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

Well explained Matt. Essential insight.

Sven

This is something that is very helpful. I had no idea that the alignment of z-spheres would affect the others down the chain. Nor did I know that the ires slider actually affected subdivsions in the mesh.

Thanks

This is really an awesome explanation of ZSpheres and helped me figure out why my branch was creasing. Thank you very much for providing this detailed information (even though its’ from two years ago).

My question is: Can you please explain the details about subdividing an individual ZSphere so that the rest of the geometry keeps its membrane (like the wrist etc), while the fingers are provided with the needed geometry to prevent overlap?

Thanks in advance!!!

Thomas