1. #1
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    Default zsphere fundamentals

    I wrote this in the troubleshooting forum, my boss suggested it might belong here too...

    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.

    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.

    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.

    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):

    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

    Other little tips:

    -I find it helps to set the preview mesh density to 1 when layout out the spheres. This way you really see the cubes for what they are, much easier to sort out overlaps and twisting errors this way.

    -Because the links are based around closest-matching sides, it helps to keep your spheres as upright as possible. Use the shift-key to snap everything to 90 degree angles when starting out, it makes it easier to visualise how the cubes will orient when skinning.

    -The closest-matching sides behavior can be troublesome if you don't watch where you zspheres are in relation to each other. Using the last hand image from above, if the thumb were to be a little higher, the skinning will attach to the upper polygon on the side of the hand. Similarly, if the index finger were further to the left, it would also try to attach to the same polygon. The best way to get used to this is to keep hitting 'a' to toggle between the skin and the zspheres, making small adjustments to the sphere placement. Once you get past halfway, the skin will 'snap' to the next polygon.

    Click the thumbnail below for an animated gif showing the snapping behavior.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	zsphereFaceSwitchAnim.gif 
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    Last edited by mestela; 10-12-05 at 09:38 AM.

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    HA! THANKS! NOW I understand it........ That explanation removed all the questions I had regarding ZSphere's....

    LemonNado

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    HI I'm new here... I want know about the zsphere because I have to make a work in my university and I really don't know nothing... please help me if you can I really appreciate it...
    I have to learn how built teh body in 3d please........
    My email is bichin_20@hotmail.com
    And I don't know if can send me examples to see how a have to work....
    Regards....

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    Perfectly clear! Many thanks.

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    Quote Originally Posted by bichin_20
    And I don't know if can send me examples to see how a have to work....
    Try some of the links in my sig, also look in the quicklinks part of the forum too.
    Long dead links removed...

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    Awesome information thanks.. Now .. can you tell me how you can snap Z spheres to axis planes when creating them? i.e. snap everything to the x axis plane?

    S

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    mestela is this your 'approach' to the problem of zspheres setup or a direct indicator of the algorithems used in Zbrush?

    Kircho

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    mestela is this your 'approach' to the problem of zspheres setup or the actual algorithem used in Zbrush?

    Kircho
    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.

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    Default Bravoo

    Cristal clear!!!! Thanks a Giga!

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    its my interpretation of zspheres, I don't have any insider info on this...

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    Quote Originally Posted by skipstah70
    Awesome information thanks.. Now .. can you tell me how you can snap Z spheres to axis planes when creating them? i.e. snap everything to the x axis plane?

    S
    I find its easier to keep things aligned if you have at least one symmetry mode turned on. Beyond that, I tend to tweak by eye, using the light/dark sides of the spheres as a guide. Also use the shift-rotate options for your camera, so that you know you're working directly from the top/left/front.

    If you need even more accuracy, take a look at zifclick, it lets you adjust all sorts of hidden zsphere attributes:

    http://www.zbrushcentral.com/zbc/showthread.php?t=22899
    Last edited by mestela; 11-29-05 at 10:07 AM.

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    its my interpretation of zspheres, I don't have any insider info on this...
    Thx mestela, allthough I did'nt really mean to evoke that question, rather, as odd as it may seem, my question was to serve as additional clarification to the conclusions I reached on the interplay between theory, fact and interpretation in scientific thought - from your initial post! - a long standing 'kink' in my philosophy of science.

    Thanks for sharing your ideas with us,
    Kircho

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    heh, thats cool kircho. reading your original question more carefully, I'm gonna go out on a limb and say this is the approach of the actual algorithm used in zbrush. I find i can predict exactly whats going to happen with any given layout, by visualising where each zsphere 'cube' will sit. The animated gif I made ( http://www.zbrushcentral.com/zbc/att...chmentid=21793 ) seemed to verify this.

    Unfortunately all this theory will be old news with zbrush 2.5, when we get those new advanced skinning tools. Oh well...

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    very informative! thanks for that nice explanation!

    greets
    froyd
    nosce te ipsum!

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    really interesting!
    any tut on how to make zspheres attractors?

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