Building a Body with ZSpheres

From ZBrush Info

by Glen Southern

This tutorial uses ZSpheres to build a body figure, then skins it in preparation for higher-resolution modeling.

Contents 1 ZSphere Reference Table 2 Previewing ZSphere Models 3 Building the Basic Figure 4 Skinning and Using the Model 5 In Conclusion

ZSphere Reference Table

Use these tables as references for manipulating ZSpheres, as you go through the tutorial.

Previewing ZSphere Models

One thing you'll want to do frequently when building ZSphere models for adaptive skinning is to preview the geometry to make sure it's what you want it to be. To do this, press the 'a' key. When you've looked the model over, press 'a' again to go back to the ZSphere modeling view. You can model while previewing, but such modeling doesn't change the underlying ZSphere structure, and we don't recommend it.

Building the Basic Figure

In this section, we'll be looking at the following workflow:

1. To jump right in and start a ZSphere model you need to select the ZSphere icon from the TOOL palette.
   
2. With your stylus draw a small ZSphere out in the center of the document window. Start with the pen in the middle of the screen and on your first stroke drag outwards very slowly. This is the “root” ZSphere, and will form the figure’s hip.
3. To add ZSpheres we need to activate EDIT mode. Press “T” on the keyboard. You should now see a red ring indicating the current size of your brush. This will become more important later in the tutorial.
4. Go to the Transform palette and click X.
   
   As we intend to model a humanoid character that is essentially symmetrical we need to turn symmetry on across the X Axis. You will now notice two red dots; one on each side of the red ZSphere. This will now add child ZSpheres in a symmetrical manner.
   When symmetry is active, the circles will show you what to expect when adding ZSpheres. When you see two circles, two ZSpheres will be added. When the two circles merge into one (which happens at the axis of symmetry), only one ZSphere will be added.
   Green circles indicate ideal placement, directly on one of the ZSphere’s “faces.” (For skinning purposes, each ZSphere is actually treated as a cube with six potential faces that can be connected to.) Red circles indicate that the placement is close to an edge between faces. ZSpheres can still be added, but you should check the mesh preview to make sure that you get the desired result.
5. To preview your mesh at any time, press the 'a' key on your keyboard.
6. Add a child ZSphere and reposition it away from the hip ZSphere. Get used to rotating the ZSphere model to look at it from all angles.
7. Add three more child ZSpheres and reposition them using Move mode. You are creating a leg at this stage and these first few ZSpheres are the thigh. The last one is the knee joint. Refer to the character workflow figure.
8. Looking form the side, angle the thigh forward as a leg would be for a figure with slightly bent knees.
9. Add a slightly larger one for the calf and a further one for the ankle.
10. Add an additional three ZSpheres for the feet and check the reference image to see how things are looking.

With the legs complete, we’ll return to the hip and build the torso.

1. Add a ZSphere in the center of the hip ZSphere. This will become the bottom of the spine.
2. Carry on creating ZSPheres up the spine and then create a large shoulder ZSphere. Refer to the images as necessary to ensure proper placement.
3. From the shoulder create the bicep, elbow, forearm and wrist.

To create the hands:

1. In the same way that the figure was created, we need to add smaller ZSpheres as children to the final arm ZSphere. These new ZSpheres will make up the fingers and a thumb.
2. Keep rotating the model to get a rough shape for the fingers. Make sure that you have a ZSphere at each bend in the fingers.

Next, the neck and head.

1. Add ZSpheres for the neck and head.
2. Add child ZSpheres to the main head ZSphere. Move them so that they become indented into their parent.

These ZSpheres will become the eye sockets. Whenever a ZSphere is moved far enough into its parent, its appearance changes to show that it will have a subtractive effect on the mesh. Edge loops will also automatically be created around these indentations.

1. Add a single indented ZSphere to the middle part of the lower face. This will become the figure’s mouth.
2. Save your model using Tool:Save As. This saves the figure in ZBrush’s native format (with a .ZTL extension).

Skinning and Using the Model

Finally, we'll show how to convert the ZSphere model to a mesh using Adaptive skinning, and how to start using that mesh.

ZSpheres in a mesh should all face the same way. The ZSpheres in ZBrush 2 are two-tone red, which helps you understand which direction the ZSphere is facing. If a mesh becomes twisted at any point, you can use ROTATE while holding keyboard ALT and rotate a ZSphere and its children. See below

Up to this point, we have only been working with a preview. Now we need to turn the ZSpheres into polygons. Before we skin it, though, there are a few settings in the Tool:Adaptive Skin menu that should be adjusted to help ZBrush create the best mesh possible.

Density: This will allow you to increase the density of the polygons in the mesh. For our example we will leave the setting at 2.

Ires: Intersection Resolution: Used to improve the mesh when more child ZSpheres are added to a single ZSphere. Set it to 30.

Mbr: Membrane Curvature: Defines how membranes will be created at L and T intersections. We can use a setting of 40.

MC: Minimal skin to Child: Affects how polygons are created at intersections. We need to set this to active (selected).

MP: Minimal skin to parent: This setting makes for a more rounded intersection. We will leave this setting inactive (unselected).

Note: These settings are only a guideline. To get experience, put the ZSphere model into preview mode ('a' key), and then change the settings. You'll see the model change in response to the new settings.

You can turn it into polygons using the Tool:Adaptive Skin:Make Adaptive Skin button.

The ZSphere figure will not change. Instead, a new model is created in the Tool inventory. Select it. To work with this model, you will need to clear the canvas (use Ctrl-n), and draw the skin on the canvas in its place.

Some tips for viewing the final model:

• Make sure that Edit, Quick, and Frame are all active on the top shelf. Quick will normally be on by default, and speeds up working with a high density mesh by disabling ZBrush’s render smoothing routines. When it is active, the Polyframe display mode also becomes available. With this display style, we can see the wireframe superimposed onto the shaded model.
• ZBrush assigns automatic grouping to a ZSphere-created model. By default, this grouping will be displayed as colors on the polyframe. You can change the display to grayscale in the Preferences, or even turn off the group display entirely.

In Conclusion

In this tutorial, we have studied how to manipulate ZSpheres in the construction of a full-body figure. The figure is now at a medium level of resolution and ready for further detailing.

To Learn About ZSpheres: Building a Hand Click Here.

To Learn About ZSpheres: Advanced Techniques Click Here.

To Learn About ZSpheres and SubTools Click Here.