UVs are generally considered one of the most tedious tasks in an asset pipeline, and I totally understand that you might hate this process and just want to get through it as quickly as possible to start painting your beautiful textures, right?
The thing is, if your UVs are not unwrapped or laid out correctly you’re going to have a massive headache down the road.
Here are some concepts that might save you time and also help build goodwill with your peers. This workflow applies mostly to VFX work, but some of these concepts might be implemented for games too.
They’re techniques I’ve learned from friends, mentors, and colleagues, and are based mainly on personal taste. I want to give a shout-out to Christian Peck, who was patient enough to teach me almost everything there is to know about UVs, and to Justin Holt, who helped me upgrade these skills to another level.
WHY ARE GOOD UVs CRUCIAL?
The task of unwrapping and laying out UV’s varies among companies. In some studios the modelers do it; in others, the texture painters.
If you’re a modeler, it’s essential to understand how painful it is for a texture artist to receive bad UVs. When a painter is dealing with an asset with multiple materials and tiles, we have to paint masks, and in painting those masks we have to make unique selections in MARI.
When it comes to UVs, good organization is extra important.
If the UVs aren’t organized, that task might take a long time to complete, and we’ll end up spending time meant for creative work on non-creative tasks, which shortchanges the project.
Here’s an example of good, well-organized UVs. Space is well used, and everything is easy to understand and select.
And here’s an example of bad UVs. Even though their unwrap might be okay and without any stretching, there’s a lot of wasted space, and it’s hard to find pieces.
If you’re a texture painter and you’re not unwrapping, it’s equally important to communicate with the modeler dealing with the UVs. Let that person know if you have requests in advance, such as organization, specific cuts, etc.
Good UVs save money and time. And you’ll make good friends. When I’m working on an asset and the UVs are perfectly laid out, I make sure to let the modeler know how much I appreciate it!
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1 – DEFINE YOUR RESOLUTION
While working on a hero asset, I like to determine the closest the camera will ever get to the object. In production, you can get this info from your lead or asset manager.
The general rule for film is that there should be double the final resolution of the piece in texture resolution. For example: If your screen output will be 2K and your UV tiles are going to be 4K, the pieces you see in your Maya screen should be doubled in your UV view.
2 – ADD SUPPORTING EDGES
Before unwrapping, another important thing I consider when modeling a hard surface object: Avoid stretching. The texture will spread around a hard edge if that seam edge isn’t reinforced properly. To prevent this, I add extra support edges around hard edges.
3 – FLATTEN CYLINDERS AND STRIPS
While unwrapping cylinders, strips or ropes, we might get a weird result, which may in turn affect your textures and also occupy an unnecessary space in your tile. There’s a cool technique native in Maya that might help you make these UV’s straight (see video below). I learned this technique from a former teacher and now co-worker, Matthew Novak (He’s a genius). Or you can use software like UVLayout (which is awesome, btw).
4 – KEEP YOUR UV’S UNIFORM
Keeping your UV’s with a consistent scale is crucial to avoid any discrepancy later on with your texture resolution. The best way to check if they have the correct size is to use a UV checker. You can find fancy checkers online, but they can be distracting, so I prefer using something simple like this one.
This is an excellent script for Maya which allows you to match the size of your tiles automatically. I found this treasure after spending two weeks organizing and scaling my UV’s, one by one, for my Gas Mask project. Yeah… at least I learned something: “Always be lazy and search for cool scripts before you start a tedious task!”
While it’s important to have UVs with the same scale, there are a few exceptions; times when it’s ok to have multiple resolutions in the same object.
Sometimes there are parts which will be closer to the camera than others, and you don’t want to have unnecessary tiles, so it’s a judgment call – yours or you lead’s. Even if you have different sizes, I would recommend scaling them proportionally (1/2, 1/4, etc) so it’ll be easier to scale up later if you need to.
Another two exceptions to that rule you can see on my Gas Mask project. My cloth UVs had to have a different size because I had cut the seams based on the actual reference and the UV tile was too large to fit a 4K square. So I kept its size and doubled the resolution in MARI. I also scaled up tiny pieces (rivets, etc.) so they could have more resolution.
Thankfully we no longer have to worry about UV seams, but that doesn’t mean we can be irresponsible with cuts. Even though in some cases you need to cut more to get more resolution (remember step one?), you must take care to avoid unnecessary visible seams.
Another thing to keep in mind while making cuts is to avoid selecting edges that end in a 5 pole, which may cause distortion.
6 – SEPARATE TILES BY MATERIALS AND ORGANIZE
This is a personal choice, but it helps me a lot when I’m working in MARI. By separating tiles by materials, you’ll save a lot of time with selections down the road.
Here’s an example of the UV’s for my Gas Mask Project and my Canon Reflex Zoom:
Sometimes, we end up having tiny pieces with different materials which don’t need to stay in the tile. So it’s up to you to judge where you should put it. Just make sure to avoid putting it too close to other UV shells, since this will make it easier for you to select it later.
When it comes to UVs, good organization is extra important. Not only you should separate them by materials, but it is also a good idea to lay it out in a smart way, making good use of the UV space you have, avoiding empty spaces if you can. This is not a rule, but please consider making your UVs look good.
UVs can be boring, but when you’re working on a team it’s essential to make things clean for other artists. Some people will sincerely appreciate that (I am included :P).