Using Topology Patches
The Retopo brush includes over 200 pre-made topology patches accessible through the IMM Viewer tabs at the top of the screen. These patches provide instant starting points for common shapes, from simple squares to complex hexagonal patterns.
Why you'd use this:
Patches accelerate topology creation for common shapes. Rather than manually placing vertices to create a grid, you can stamp down a pre-made patch and adjust it to fit. This is particularly useful for starting large areas like torsos or establishing cylindrical forms around limbs. See below how we dropped an "eye patch" onto a mesh. Now imagine the time savings of this one-step operation versus creating fine tuning that retopology from scratch.
Note:
These tabs are a new addition to the IMM Viewer system. (Learn more about the IMM Viewer here.) Previously, IMM brushes displayed all contents in a single scrollable list. The tabbed organization makes patch selection much more efficient.
Placing patches
- Select a patch from the IMM Viewer.
- Place a vertex on your model surface. This becomes the patch center point.
- Hold Alt and drag to place and scale the patch.
- Before confirming, you can:
- Drag to adjust size and position. We show this in the image below. Note how the manipulator icon changes to the patch symbol.
- Swap between similar patches by selecting different patches from the IMM Viewer, like so:
- Press Alt to display green borders for free-form shape editing.
- Drag to adjust size and position. We show this in the image below. Note how the manipulator icon changes to the patch symbol.
- Click on the surface to confirm the patch.
Patch density visualization: The orange wireframe overlay shows the actual polygon structure of the selected patch. Denser patches (like a 6×6 grid) have more subdivisions, giving you finer control in specific areas. Less dense patches (2×2) are better for broad coverage.
Free-form shape editing
When green borders appear (after pressing Alt while a patch is active), you enter free-form editing mode. In this mode, you can click and drag the patch boundary vertices to conform to your model's surface contours or design needs.
In this example, we start with a simple 3x3 grid (left) with eight total edge vertices. By pressing Alt to enter the free-form editing mode, we drag laterally along the top and side edges to create the additional vertices you see here:
Use these additional vertices to refine and reshape your new patch mesh as you see fit.
Free-form patch editing is particularly useful for wrapping patches around curved surfaces or conforming rectangular patches to organic forms. For example, you might place a square patch on a cylindrical arm, then use free-form editing to bend the patch to follow the arm's curvature.
Overlapping patches
If you place multiple patches that overlap, ZBrush generates the geometry for each patch independently. The patches will overlay each other without creating conflicts or merged vertices. This behavior is similar to applying real fabric patches that stack atop each other.