ZBrushCentral

How to stick a Zsphere on the back of the starting sphere?

ZBrush Usage Questions
#1

Hello there,

I’m trying to get a simple clean box mesh. When I put the initial Zsphere down (with shift), I turn on x and y symmetry to place a sphere on it nice and clean. So the mesh will be straight.

However when I turn it over to put a sphere on the ‘open’ end in order to close the mesh I find that I can’t place a sphere in the exact centre. If I try to do that it places the sphere somewhere deep inside the mesh.

I can place it off centre but then I don’t get a straight clean mesh.

If this is not clear enough I’ve provided a script.

thanks.

#2

After creating the ZSphere, why don’t you simply move it to where you need it?

#3

First, if you are working with ZSpheres, you need to download and install TVEyes’ XYZAdjust ZPlugin . It’s only the most damned useful script to have when working ZSpheres.

Next, use it to select the root ZSphere (point with cursor and press the K key), then adjust the resolution to 1 or whatever. Press the space bar to close the XYZAdjust interface.

The root Sphere will now work like any other ZSphere.

Sven

#4

Yes Aurick,

there is that of course. but everything was getting a bit wobbly. I have eventually realised that my problem was in forgetting about the axis constraint buttons. I got used to using the symmetry buttons to constrain movement when I should have been using the axis constraint buttons.

BTW, Aurick you didn’t mean let the sphere lodge inside the mesh and then somehow move it to the outside did you? Is this possible, how is it done.

#5

I’ve just realised some more stuff that helps me to understand what is happening. I’ll post it in case others find it helpful.

In the shot that I’ve posted you can see the Zsphere and the resulting previews. In one shot the Zsphere that is placed on the ‘open’ end of the originating sphere is slightly off centre. But when I tried to move it to its true centre, as you can see the mesh has gone strange even though I have only moved it a tiny amount.

Although I don’t understand the math I have a strong feeling that these problems that I have been having are something to do with the mysterious “gimbal lock”.

If this is the case then I have been attempting to do the impossible. This is just a hunch. So I may be totally wrong here.

Attachments

spheregimbal.jpg

#6

I usualy enable X, Y and Z symmetry, add 2 zspheres and then move them into position by dragging the linking spheres (grey spheres). Dragging directly on a zsphere during this initial stage can cause problems with the skinning.

It seems like a bug to me as this issue did not exist in 1.55b.

#7

Of course, xyz symmetry, slaps head, doh!.

So it isn’t a gimbal lock thing.

Then after putting the two symmetrical spheres down they can be moved symmetrically with xz symmetry and a combination of z, y axis restraint.

It is all clear now.

thanks TVeyes

pink.jpg

#8

How about this?

#9

I don’t think there is any problem with the root zsphere Sven. It is a problem derived from the new zsphere hightlighting in Zbrush 2. The situation you show can also occur in other parts of a zsphere model.

Try this: 1. Draw the initial zsphere and add another with XY symmetry enabled. 2. Rotate the zsphere to reveal the back. 3. Enable Transform>Move and click the root zsphere. 4. Now draw the 3rd zsphere to the back of the root zsphere.

In situations where you rotate the tool to add another zsphere on the opposite side, and the last created/active zsphere is behind that, zbrush selects the last created/active zsphere instead of the one beneath the cursor. Rotate it less(or more) and you should be able to see which zsphere will be added to. So definetely a bug.

There is also the problem of moving the 3rd zsphere (from the above example). The 3rd zsphere will invariably twist if you move it without the proper symmetry or without snapping to the proper axis. The 2nd zsphere does not display this behaviour. An ‘UnTwist’ script is perhaps needed;)

btw, in the above the 1st zsphere is ment to be the root.
#10

Yup, you’re definitely correct. Is it a bug? For sure there’s a gotcha there that will continue to confuse a lot of people during ZSphere construction. (got me at least.)

Thanks for the heads up. :smiley:

As to the twisting? I think there’s something else going on there. I have to experiment more with it I guess… :rolleyes:

Sven

#11

So the answer to my original question is: just use xy symmetry and don’t worry about the postion of the Zspheres because whereever they are the new sphere will be added on nice and square (as long as you don’t try to force it to be square by placing it squarely behind the original).

So don’t force the issue just use xy sym and trust that everything will be OK.

As this script shows.