ZBrush: All about Polygroups
Polygroups are a useful way of grouping certain areas of a single subtool, to make selecting and working on them easier. You can hide/unhide polygroups, mask by polygroups, sculpt on them and assign individual materials to them, making them a very useful organisational tool.
CREATING POLYGROUPS
Press Shift + F or press the PolyF button to activate polyframe view, which is like a grid running over the surface of your model. This shows different polygroups as diferent colours.
To make a polygroup, mask off part of your sculpt then press Ctrl + W – it will change colour to signify being part of a new group. (Alternatively, open the Polygroup palette and click the Group Masked button. NB: The From Masking button is not recommended as it will not preserve previous polygroups.)
Optionally, click the polygroups tab in the right hand Tool palette. Click Auto Group. This will automatically split up the model into what zbrush thinks are appropriate pieces.
‘Merge Similar Groups’ can be clicked to add similar objects into a similar polygroup- eg if tyres on a car are 4 repeated elements, they will be merged into one polygroup.
Depending on your subdivision level, the borders of polygroups can look quite ragged. If you go to the Geometry palette and click the Group Loops button you can smooth the boundaries of your groups. The options nearby will help you refine this smoothing process. NB: This will create a new, very narrow polygroup along the seam.
Group Visible: This option will combine all visible polygroups into one.
HIDING/SHOWING POLYGROUPS
Ctrl + Shift + Click on a poly group to hide unselected groups. Do the same again to hide it and show the others.
Ctrl + Shift + Click on an empty space to bring back all poly groups.
Split Groups – This option in the Subtool palette will allow you to split a tool into subtools, based on how it is divided into polygroups.
MASKS REFRESHER
Since polygroups are mainly created via masks, here are some masking reminders:
To mask, hold Ctrl then paint on your model, this will darken the selected area.
To remove polygroups, just mask the whole object and press Ctrl +W to make one single Polygroup again.
There is a masking palette, with useful options including Grow Mask to make it extend outwrds, Blur Mask and Sharpen Mask to adjust your mask edges.
MAKING POLYGROUPS WITH ZMODELLER BRUSH