9. It's now time to create the arms, which will be built using the same methods as before. We create three sections to form the elbow, wrist, and hand (Fig.09a & Fig.09b).
10. The last ZSphere to be placed is the one on the back of the lower knee joint, duplicating the bone that sticks out in the concept drawing (Fig.10a & Fig.10b). Once all of the ZSpheres are placed, we can move into the refining stage, part of which is creating the hands.
11. Surprisingly quickly, we now have the whole character built and blocked out, and it's time to go over it with a tweaking pass. Use the Scale and Move tools to try and match the concept art in proportions, pose and scale. The closer we get now, the easier the retopology work will be.
A ZSphere model is nothing until it's meshed, and that's where Adaptive Skin comes in. Adaptive Skin is a method for creating a usable model from ZSpheres. It also comes with the handy option of previewing the model before creation. Open the Tool menu and find the Adaptive Skin palette.
There are plenty of confusing options in the palette, so here is a quick explanation of their functions (explanations of almost any tool in ZBrush can also be found by hovering over the tool and holding down Ctrl). Under the Adaptive Skin menu (Fig.11a) we have the:
• Preview button, which turns on and off
our meshing. You can use the hot-key [A] to enable and disable this. It's very useful to keep checking the mesh to see how your ZSpheres are looking.
• Density, which calculates the number of
subdivisions that the mesh should have. A density setting of one will be very low poly; a setting of two will be four times that, and so on.
• Ires (Intersection resolution), which is the number of consecutive ZSpheres that will be used to create a single object when the mesh is converted into polygons. This can be visualised by thinking of one sphere with a two-segment chain on either side. With an Ires of 0, each sphere will turn into individual spheres with a few joining polygons to connect them together. An Ires setting of one will turn the three middle spheres into one flowing cylindrical mesh, with the outer two spheres still maintaining their spherical shape.
• Mbr (Membrane Curvature), which adjusts the smoothness in the T- and L-shaped intersections. The higher the setting, the smoother the curve will be, whilst a low setting will maintain the shape of the right angle.
• MC (Minimal skin to child), which ignores the child* of the section of the object, using it to connect two parts together but not contributing any polygons. This allows smooth transitions between new branches and can help eliminate twisting and collapsing.
• MP (Minimal skin to parent), which ignores the parent** of the section of the object, using it to connect two parts together but not contributing any polygons. This allows smooth transitions between new branches and can help eliminate twisting and collapsing.
• PD (Pre-divide), which lets you specify a pre-division resolution to match objects which are attached using connector mesh or local mesh features.
* A ZSphere created off another ZSphere is known as a "child” object.
** The original ZSphere is known as the parent (think of it as a mother and daughter holding hands!)
Once you understand the features, Adaptive Skin is not too complicated, and it's a very quick way to block out a character, animal, alien – or even a car! So now that we have a good set of Adaptive Skin settings, we need to modify the mesh a little to make it optimal for animation and speed up the next optimisation section.