As many of you know, I absolutely hate UV unwrapping. It’s a fairly time consuming, tedious, and to be blunt, boring, compared to the other stages of the 3d modeling pipeline. Most people really hate UV mapping. Why do we all hate UV unwrapping? It’s tedious. It’s boring, since we don’t see the results. It can take quite a while to top it off. So in short, it’s a pain. However, it is as important, if not more important, as the other stages of 3d modeling.
But what is UV unwrapping? The basic idea is really simple actually. 3D modeling means that we generate a 3d model/mesh with information in 3d space. UV unwrapping does not matter at all for the modeling part of the pipeline. But what if you want to add colors and surface detail? Textures are important for that, and that’s where UV unwrapping becomes important. UV unwrapping is most important for the texturing part of the pipeline. By this, I mean that the adding textures is basically undoable without a UV layout. A bad UV layout results in really warped texture application and at best will give you some sort of really odd texturing that, while not warped, looks fairly weird. The reason for this is that a texture map is, at its core, a 2d picture. Texture application to a 3d object is inherently a 3d process. The means of translating the 2d coordinates of a texture image to 3d space is done by UV maps. The basic concept is pretty simple. What a UV map looks like then is the 3d object ‘flattened’ onto a 2d plane. Something like this:
The basic idea, like I said before, is to translate 2d points to 3d points. In practice, this is fairly difficult to do.
There’s a ton of great tools for modeling, sculpting, and texturing (and I’ve written about these tools at great length). However, UV unwrapping is one particular area that doesn’t have a ton of tools out yet. To be fair, there have been great improvements in this area, with tools in Maya like unfold and unwrap. There’s also the automatic unwrap tool, which, as I’ll explain later, is hit or miss depending on what you have. What certainly does not exist is a 1 click UV mapping tool that automatically generates the perfect UV map for your model. Partially this is because UV unwrapping cannot know what part you want to have more detailed textures versus what part shouldn’t be as detailed. The other reason is that automatic unwrapping just isn’t quite there yet. There are some tools that exist that can do automatic unwrapping, and they cost quite a bit of money. I, unfortunately, have used none of them.
There is no doubt that there are still a ton of improvements to be made with UV Unwrapping. I have always found myself mind boggled that Maya’s automatic tool chooses to scale the tiniest set of faces of my model to take up 50% of the plane. Why would that make any sense at all? These areas can certainly be improved. But things like where seams have to go, what part of the model should be emphasized, this is something that no auto unwrapper can figure out without human input.
There are, of course, tricks to speed it up. My current project has tons of pieces, but they are all duplicates. Unwrap one, and you unwrap them all. Sometimes separating out objects makes the process go a bit faster as well, since you have less faces to place onto the texture plane, so that gives you more space to work with. Tools like unwrap and unfold can also make the process go much faster.
Ultimately there’s no easy answer to how to unwrap. While there have been improvements, it’s still a tough and tiring process and probably one of the most important processes as well, since it can literally make or break your textures, and consequently, how your lighting interacts with those textures. Geometry is great, but it’s not helpful if you don’t have the UVs to back up the texturing. The best way to think of unwrapping is to think of your model as a cardboard object that you are now breaking into pieces to lay flat so that you can paint them.
Perhaps some day we will have something to make UV unwrapping painless. However, that day, unfortunately, is not today.