This guide has been written for ZBrush 3.5 and below. In ZBrush 4 you would just use the topology move brush which only moves areas that are directly connected. This works pretty well.

In this tutorial you are going to learn how to use the morph command and the smooth tool to make selecting easier in complicated areas, such as a mouth. This simple technique is however not limited to the example shown below but can also be used whenever selecting or masking a part of the model is too complicated.

The problem

Consider this head model. The head is currently displayed at division level 6 and consists of about 5 million polygons. To open this guy‘s mouth, the first approach would be to try to separate the lips using the Move brush. Because the Move brush simply moves everything in a certain radius and because it does not know what an upper lip and what a lower lip is, it deforms everything.

That‘s why we need selections. To drag a selection, hold down the CTRL key and try to mask out the upper lip (enable the lasso mode of the selection tool first - button in the right navigation bar).

In most cases you will notice that - even with a Wacom tablet, you will not be able to follow exactly the contours of the lips. If the lips overlap in the inside of the mouth, there even is almost no way of drawing a precise selection. You will always have parts in your mask that don‘t belong as seen in the next image. After using the Move brush again, the parts that should not have been included in the selection get clearly visible.

You could of course use topology masking in ZBrush 3.5, although I find that the results are still not very accurate. You always end up having something in your mask which you don't want.

The right way

First, go to the lowest division level. Even at this level, it is very difficult to select all the polygons of the upper lip, especially at the corners and on the inside of the mouth. At least it is very fiddly and time consuming.

Now store a Morph target to ,freezes‘ the mesh. You can always come back to this stage no matter how long you deform the head with the sculpting brushes. Just remember that all the next steps need to be done at this subdivision level, this makes life easier.

Now use the smooth brush and completely flatten the mouth area. Don‘t worry, you can always restore the mesh thanks to the stored morph target.

This looks ugly, I know. But now, that the mouth area is almost as flat as a plane, you can easily see which polygons belong to the upper lip and which belong to the lower lip.

By the way, there is no hole in the model because the inside of the mouth has also been smoothed but that does not matter since we also want to move the inside of the mouth when opening the lips.

In the next image I have enabled the grid to better see what‘s going on. You should do this too.

What you see in the previous image is just a smoothed version of the lips and the inside of the mouth. In the next image I added some colors to better see where the upper and lower lip are. As a result of the smoothing, the whole are has shrinked but there are no more hidden or overlapping polygons which makes selecting in the next step easier.

You can now simply use the lasso selection tool again and drag a selection around the orange area to mask the lower lip, but we want to store the selection in case we need to reuse it. In ZBrush 3, stored selection are called Polygroups. To create a polygroup you have to hide everything that should not be part of the polygroup. So, use the CTRL+Shift combination and make sure only the lower lip is visible at the end.

Now go to Polygroups and press the Group Visible. Unhide by holding CTRL+Shift and clicking in an empty area of your canvas. If you turn on the Grid view again, you will notice that the lower lip is displayed in another color. That means these polygons are in two different polygroup. To select a polygroup hold down CTRL+Shift and left click on a group.

Now we need to restore the initial shape of the head again. So go to Morph Target -> Switch and voila, everything is back to normal and ZBrush even reminds the previously created polygroup.

To open the mouth now, select the polygroup (CTRL+Shift + left click on the polygroup) to hide everything but the lower lip, hit CTRL+A to select everything that is currently visible and unhide (CTRL+Shift + click on the empty canvas). You have just masked out the lower lip.

Now you can use the Move brush or any other sculpting tool you want, the lower lip will not be affected. Inverse the mask (CTRL+I) to work on the lower lip.

That‘s a lot of text for a very simple procedure but I tried to be as detailed in my description as I could and I tried not to leave out a step.

As you can see in the next image I created several polygroups in my model for easy selecting. One for the lower lip, one for the upper lip (which got a bit big, but that‘s not a problem) and one for the eyes. The latter is especially useful if you want to move the eyebrow without affecting the eyelids or vice versa.

I hope that you learned something from this tutorial and if you have any questions about what‘s written on this page please email me and I will try to help you.

Patrick Eischen