Texturing laying out Uv's part I - Levitateme In this tutorial, I am going to try and teach people my method of laying out uvs. I think laying out uvs is a art form, I think everyone has there own style, "quote me..." I do think this tutorial can help out people who are getting tired of weird uv problems. Some benefits of having properly laid out uvs are. When painting your brush size shouldn t jump sizes, from uv edge to uv edge. Plus you should have little to no distortion once you place your textures down. I am using Maya 5, this tutorial should apply to anyone who uses a 3d program. Hopefully I wont get repetitive on some topics. Well I guess that is all I have to say. So you see this low polygon game character. Heavens no, don t fret! These tut will even work on your umpteen polygon characters. I use this Image when I am setting up UV s.
I use to use a checkered image, but I found this has many more benefits. If you look at the numbers for exp, you can see if there being distorted much easier then a blue checker box. Also the white lines that run through the image, they give you another good reference for finding distortion. You can save this image to your HD, and follow along If you likes. One main thing I would like to point out is. If your using Maya put your Projection Center X to 0 when applying a projection. I mean this only if your character is facing in the Z direction. I always have my models split right down the middle at center axis. This will alleviate a lot of potential problems. As for Projection Center X, value of 0, this gives a lot less distortion. here is the character, no uv mapping yet...now the work begins...
This is something I do, you can ignore this step if you like. I split up my geometry in pieces main pieces this way in the uv editor its very clean and not confusing. If you have construction history on in Maya, you will have all your translations at 0 0 0. So once your done mapping your model, just enter 0 0 0 everything is snapped back to its right position. Then you would just combine, merge vertices. I just find this less of a headache.
Ok I am going to select the faces on this stomach, under Show > Isolate Selected >View selected. I only see my stomach now. I think a general rule is you want your projections to match the rough shape of your geometry. I used a cylindrical projection for the stomach. I think I have used spherical projections...never. That is just me I guess, I think I get to much distortion with them, around the poles I mean, cats butt. You see there is distortion along the spine. That is fine, ill show you how to get rid of this. You just need to move your uvs until the texture looks the same, and matches with the rest of its stomach. Its just a matter of moving uv s until the distortion is gone. What I do is see the distance of the uvs from the other uvs, guesstimate that, and try to move to the same position. That generally works best.
Earlier I mentioned poles cat butt my Aussie friend calls it that. This happened using my cylindrical projection. When I get poles this is what I do. I selected them faces, instead of spending a lot of time unwrapping them, I put a planar projection on them faces in the Y direction. Scaled the uvs down until the numbers are matching with the rest of the stomach see its importance now
Now in Maya I selected the bounding edges. Then I did a move and sew very handy I just tweaked the uvs until the numbers matched again. Nothing complicated. I use this same technique for like the top of a persons head for exp. The tails uvs are very distorted. I put a cylindrical projection on it, set its center x to 0. Then rotated until it was moving along the general slope of the tail. Later I just scaled the uvs to match with the numbers of the stomach. Rule of thumb yes yes. Have matching numbers all along your model. The head is generally a cylindrical projection. For the Digimon, I will use a planar in the X direction.
There is a little distortion on the edges of the head. Just some tweaking is needed. For the arms, since they are generally a cylindrical shape, I will use that method of projection.
Now this is a trick I have never seen done before, I would say in general people hate modeling the index, middle, ring, pinky finger separately. If you have just duplicated them fingers why map each one, there is a very fast workaround for this. I did the projection for the left finger, since I have separated the fingers from the arm, I can just transfer uvs to the other 2 fingers. Wait no cant... The middle finger has different uvs from the other 2. So when you do this make sure you have the same number of uvs. Not a great example...cough... But I did save the time from doing the right finger...so to do this in Maya, just extract the mesh you want to transfer onto another. Then go to Polygons > Transfer > and turn on just the uv options. I did apply this to the Digimon s toes, worked fine, but now you know when you can do this.
That is a hopefully good understanding of some things to do so far. Since this character is not insanely complicated, ill just mention some things here. If you have uvs that are over lapping, you want to move them until you see the distortion go away. In Maya there is RELAX. I tend to not use this. When I do use it, its for untangling uvs that are to much work. I use the World space settings with a Max Iteration of about 100. If you use this tutorial, look at your numbers/checkers, you want them to all be the general same size. Ill get into that further in a minute. The toes I just did the mapping for one, then transferred uvs. But there is something I want to point out. This is the uvs for all 3 toes. If you were to paint a texture on this, the texture would transfer to all 3 toes. That can save you some time, but if you are going to generate normal maps later, for exp, you will get a distorted normal map.
To get around this, I leave the uvs how they are, I set up my high res model to get my normal map. I then select a uv on each of the toes, but one. Then I go to select shell, then move the shells out of the 0 to 1 space. I then generate my normal map. No distortion on the normal map. I just move my uvs for my toes back. This can be applied to the fingers as well. But if your character needs different texture for each finger, just move the uv shells. Now lets say you have all your uvs laid out. If you separated your geometry, now set all transformations back to 0 0 0. Then combine and merge vertices on a very low number. Before I do this, I select all my geometry and make sure that noting is overlapping in the uv editor. The head over the hands uvs for exp. Now that your back to the original shape, if you do have some uv shells overlapping, select a single uv then go to select shell and move it. Now I go to polygon layout and select all my uvs with these options below. Now all my uvs are in the 0 to 1 space, ready to start texturing. If you have a ton of little faces all over the place, that is because some of your uvs are not merged, you can toggle on uv borders in Maya, then make sure everything is right. If not just select them uv s that are not working and merge. Then layout your uvs.
All my uvs are in the 0 to 1 space. For my final step i select all my uvs in my 0 to 1 space and scale them up. This way my numbers are very small, I can see distortions much easier. This is a last step, then i undo to get back to 0 to 1. So in finishing up, remember to have your numbers/checkers matching the overall size throughout your model. Make sure to have all your uvs in the 0 to 1 space.
Sorry this is geared towards Maya users with the definitions. I am hoping this can help out users of other programs as well. After writing this tutorial I realized I just covered the simple stuff. I didn t get into overlapping uvs, untangling uvs, things like that. If I get any replies to that, I wouldn t mind doing a quick tutorial to add onto this. But that is my method, I use it for all my models, so hopefully this should be able to help out some people out there. Ciao.