Unwrapping Suzanne

Easy as it "seams"

A mesh can be organized with the use of seams which provide a nice way to create "Face Groups" prior to doing an unwrap. These "groups" are just a way to call a selection of faces, and not a separate entity like Vertex Groups are. Seams are created by selecting a loop of vertices in Edit Mode and pressing CTRL-E or, using the menus, by selecting Edge Menu->Mark Seam. A thick continuous line will be drawn in the 3D window showing the newly created Seam. It is possible to visualize this seam both in Edit Mode and in Face Select Mode activating the Draw Seams option in the Edit buttons.

Once a seam is marked, we can select each side of the model in Face Select Mode, by selecting first a face, and then pressing the LKEY. All connected faces that are isolated from the rest by this seam will be selected. By strategically creating seams in our model, we will be able to work later on with this group of faces only, thus greatly simplifying our job.

Ideally we should mark a seam wherever we want the UV map to have "cuts". For instance to isolate the legs and arms of character from its torso.

Let's do some real work. Add a Suzanne to our scene, and select the vertical central loop of vertices, be sure to completely select it. Press CTRL-E to mark this loop as a seam. Let's test it, enter Face Select Mode, we should see the seam. Select a face, and the press LKEY, all faces from this side should have been selected. Had the whole model been selected instead, this would mean that we have missed some vertices from the central loop, if this is the case please go and select the missing vertices. Easy, right? That's the idea.

Create some more seams, try to isolate complex zones from each other, like the ears from the head. When we unwrap it, these seams will act as cuts in the surface and also in the UV map.

An interesting loop to add a seam to is the main face loop of Suzanne, so we can separate the front side from the back

Unwrapping the mesh

Open a UV Editor window besides the 3D viewport. Now select the model and enter Face Select Mode.

Select the faces in the left and right side of Suzanne's scalp including the ears. We are going to unwrap these groups using the Sphere option which will give us a nice starting point for LSCM later on. It is very likely you'll get something "almost" perfect. However I always get a couple of faces in the wrong side of the map. This can be fixed easily manually but I'm such a lazy guy that I will not do anything at all. Press CKEY in the UV Editor to enter Face Selection Mode (this one is a nice one). Select some of the faces around the ears, just the ones that look radially unwrapped. Leave this mode and select the vertices in the upper central zone. The ones in the central lower part are a bit tricky. We will do them in a while. Now, with these vertices selected, press PKEY. This is the Pin command. It will fix the locations of the selected vertices so nothing can damage our layout. More on this later.

Now that we have pinned the nicely unwrapped vertices, unselect everything in the 3D window but the two faces in the chin. In the UV Editor, pin the central two vertices of these faces that were unaccessible previously. We are almost done.

Now it's time for some LSCM magic. In the 3D window select all faces linked to the ones in the chin, (use LKEY, remember?). You should not select the ears this time. The selected faces should appear mapped in the UV editor. Now select all vertices in the UV Editor and press EKEY. Blender will ask about doing LSCM. Accept the query. Wonderful things will happen. Suddenly, the "unpinned" faces will be relocated to a nicer location, overlapping of faces is magically fixed. Cameron Diaz is on the phone.

If you select the ear faces in the 3D window, you will see they are still there, don't worry about them right now.

Now we should make some space in the map for the front faces. We can do this by selecting the border vertices and scaling them. The UV Editor supports the Proportional Editing Tool (OKEY) just like meshes. It is very useful for making some space here without overlapping faces.

Once we have made some space, select the front faces, set the viewport to the front view, and mapped the faces using the "From Window" option. Scale them down a bit in Y or X so they fit in the space we have reserved for them in the map. Just press SKEY followed by YKEY or XKEY like you would do with meshes.

We now have the front faces nicely unwrapped in the UV Editor.

If we unselect the currently selected faces in the 3D window, we will not be able to see them anymore in the UV editor, but you can activate the Draw Shadow Mesh option in the UV editor's View menu to help you visualize the unselected faces.

"Stitching the Map"

Now we need to join these two "islands". If you keep CTRL pressed while selecting a vertex, all concurrent vertices will be selected too. This can be toggled on with the Stick UVs to Mesh Vertex option in the Select menu of the UV Editor. Select a vertex from the border, you will see its homologue in the other island selected too. "Stitch" them together by pressing VKEY. They will merge into a vertex located at the middle of the original ones.

Now, it might be a little tedious to continue vertex by vertex. Select all vertices in the border of Suzanne's face. Now stitch. Pin the selected vertices. Remember to pin only if there are no overlaps. If after a stitch, there are overlapping faces, keep stitching the rest and do not pin the stitched vertex.

Now we have both islands stitched. However there are zones where faces are overlapped. Be sure to have pinned the "nice" vertices and do some LSCM again. Select all vertices and press EKEY. If you do well, each LSCM step will fix vertices located at overlapping faces, that you should pin to "keep".

Feel free to scale or move the vertices before doing an LSCM calculation but always select pairs to keep the symmetry controlled.

"Solving the Ears"

Now we are going to use the same methods explained before, to fix all overlapping faces in Suzanne's ears. It's better if you work each side separately.

First, select vertices in the border area, where the ear should join the rest of the head. Just as we did before, select in pairs and stitch. Pin everytime you stitch, now pin those vertices nearby the stitching that are not overlapped. Select ONLY the vertices of the ear we are working on, and do an LSCM step.

Now, stitch again the vertices in the border area of the newly generated "island". Again, pin after stitching and also pin the following row of non-overlapping vertices. Do some more LSCM. Proceeding this way, we will get an almost completely pinned ear, with no overlapping whatsoever.

You can do this manually, by selecting vertices with CTRL pressed and then moving them away but it is harder and more boring. Besides, the LSCM method gives us an optimized map in order to avoid stretching in the textures.

There is not too much work left to do. We can select the eyes face groups and map them From Window or LSCM. Since the eye meshes are not linked to the rest of the mesh, the Stitch command will not work. If you want to merge the eyes with the rest of the face you will have to do it with the Weld command (WKEY) instead. However, I prefer having them aside, so when painting the texture I can give some extra detail to the eyes more comfortably.