Join Chris Reilly for an in-depth discussion in this video UV mapping overview, part of Game Character Creation in Maya.
UV Mapping allows you to add colors and textures to your character by wrapping flat images on to your model's geometry. UVs are components that represent the local texture space of each polygon face. So in addition to edges and vertices, your polygonal geometry also has UV coordinates. UVs look very similar to vertices. But instead of controlling the location of geometry and space, UVs control the way a texture, image, or pattern is mapped onto each face. So in the example file here I have two cubes that are identical in size.
But you can see they are textured pretty differently. So the cube on the left has a nice checker pattern where the squares are very even. The cube on the right has a checker pattern where the squares are very distorted. There is some stretching here that's looking a little funky. So let's take a look at the UV maps of each one of these cubes. I am just going to select a cube on the left and bring up the UV Texture Editor. That's under the Window menu. Here, I can get a look at the UV map of this cube.
So let's say that we wanted to apply a texture to this cube that was on a checkerboard. Well, it would be a process pretty similar to drawing on an unfolded cardboard box. So you can see each face of the cube here is laid out flat in the UV Texture Editor. So this UV map would be very nice and very easy to work with, because we could very easily draw, let's say we wanted something in the top-left corner on one of the faces, we can just draw it on a flat image. That would map pretty reliably to a corner of the face that it corresponded to on the 3D geometry.
Let's take a look at the cube on the right. So this UV map is looking pretty funky, so you can see things are stretched. It's not as regular as a UV map of the cube on the left and if we were to try to texture this cube using this UV map, there would be a lot of problems. You would get a lot of unexpected distortion. So let's go ahead and look at a couple of quick edits we can do to minimize some of that distortion. So in the UV Texture Editor, I am just holding down my right-mouse button and I am going to select UV. Let's look at this one. Just like vertices, you can move UVs around using the Move tool.
You can see as I drag this, in the Perspective window that texture is already changing. So I am already just with that one little move I am getting a lot less distortion. So the overall goal when you're UV mapping a piece of geometry is to minimize the amount of distortion that you get going from a flat texture, mapping it onto the 3D geometry. Obviously when you are dealing with a video game character, your geometry is going to be much more complicated than just a simple cube. So it's pretty unlikely that you will completely eliminate all stretching and distortion in your UV maps, but the overall goal should be to minimize stretching and distortion or to move it to a place on your character that's less visible.
- Optimizing, extruding, and sculpting geometry
- Modeling a character's head and body
- UV-mapping the head and body
- Mirroring and texturing
- Setting up the skeleton
- Rigging the head and body
- Skin binding & weight painting
- Controlling animation with scripts in Unity