Changing the different parameters for Dynamic Subdivision can drastically change both the visual appearance of your model and the performance of ZBrush itself. The settings below will help you fine tune your use of Dynamic Subdivision to get the most out of the feature.
The settings are in the Tool>Geometry sub-palette.
Dynamic mode enables Dynamic Subdivision mode for the current Tool or SubTool.
Remember that when first enabling this mode for a model it will not have any apparent effect until you adjust the QGrid, Flat Subdiv and/or Smooth Subdiv sliders to tell ZBrush which mode(s) you wish to use and how strongly.
Hotkey: D or Shift+D as a toggle.
The Tool >> Geometry >> Dynamic Subdivision >> Apply function converts the model’s Dynamic Subdivision to Classic Subdivision.
This only generates multiple subdivision levels with Flat and/or Smooth modes, due to the fact that those algorithms are based on quadrangle. With QGrid (Quick Grid), using Apply will generate the appropriate geometry as Subdivision Level 1 with no additional levels.
These modes do work together, however, with QGrid being applied first and then followed by the other two. So if your model has settings of 1 QGrid, 1 Flat Subdivision and 3 Smooth Subdivision, using the Apply function will create a model with 5 subdivision levels. QGrid is created as the first subdivision level, followed by a level of Flat Subdivision and three more levels of Smooth Subdivision.
After clicking the Apply function, your model will appear to be unchanged due to the fact that Dynamic Subdivision is a WYSIWYG system. However, you will now have real high-resolution polygons with which to further refine and detail your mesh.
QGrid (Quick Grid)
The QGrid (QuickGrid) slider defines the number of grid-style subdivisions applied to the model. By default, it applies a uniform grid over the entire model. Each increment in the slider’s value quadruples the number of displayed polygons.
The QGrid function works in collaboration with the Coverage, Constant, Bevel and Chamfer options.
When Transform >> PolyFrame is enabled, the QGrid topology is visible but with less intensity than the base mesh topology.
Flat Subdivision and the QGrid Subdivision are based on the same algorithm except that QGrid can use extra options:
The Coverage slider defines how the grid pattern subdivision is distributed across the surface:
- With a value of 1, the distribution is uniform across the surface.
- Lower values slide the highest subdivision toward the edges of your mesh.
While QGrid is active you can see the effect of the Coverage slider in real-time.
To observe an example of this, simply load a Tool >> Initialize >> QuickCube mesh, then set the QGrid slider to 1, the SmoothSubdivision slider to one and change the Coverage slider values. At 1, you will have a very rounded cube because the entire surface is being divided uniformly. As the value approaches 0 you will get sharper edges due to the fact that most of the polygons will be pushed to those areas. (The main surfaces of the cube will have fewer polygons, resulting in less smoothing and flatter sides.)
The Constant mode, when enabled, keeps the QGrid subdivision at a constant distance from the base mesh edges, providing uniform topology along these edges.
This setting is enabled by default as it is important to keep a constant radius along the edges when the QGrid Bevel and/or Chamfer modes are active.
The Bevel mode moves the edges of the QGrid subdivision to produce a flat angle along the mesh’s edges.
The Coverage slider as well as the QGrid slider values impact the size and accuracy of this bevel.
The Chamfer is similar to Bevel in that it operates along the mesh’s edges. However, the edges will be more rounded.
The Coverage slider as well as the QGrid slider values will have an impact on the size and accuracy of the Chamfer.
The Flat Subdivision slider defines the number of grid-style subdivisions applied to the model. It creates a uniform grid across the model’s surface. Each increment in the slider value multiplies the number of rendered polygons by four but no actual smoothing is applied to the surface.
(This is similar to turning off Smt before using Divide with Classic Subdivision.)
Because Flat subdivision does not smooth the surface, it doesn’t make use of the QGrid options described above. The subdivided shape is almost identical to using QGrid with Constant, Bevel and Chamfer all set to 0, except that the polygons will be distributed uniformly.
The Smooth Subdivision slider defines the number of standard subdivisions being dynamically applied to the model. It applies the same Catmull-Clark subdivision smoothing over the model that you would get using Tool >> Geometry >> Divide. However, these subdivisions are dynamic and display virtual geometry rather than actually creating new sculptable polygons. Each increment in the slider’s value by one will divide the number of polygons by four.
For tech buffs, Catmull-Clark Subdivision splits each quadrangle into four new polygons and uniformly smooths the resulting surface. Triangles are split into three quads and the surface is not smoothed. A model with both tris and quads will be partially smoothed with the first subdivision (wherever the original quads are to be found) and fully smoothed with the second subdivision.