I'm unwrapping my first big model and I'm starting to going crazy about one thing. I've got one piece with more complicated shape (many bends). I've heard that for best normal map baking results I should keep outer edges of uv islands perfectly straight. While with shapes that are already almost straight it is not problem, it becomes for me unclear with shapes like this below.
On the left I have straightened its outer edges and on the right there is untouched island.
The island on the left it's little stretched and texture is following the direction of geometry.
Island on the right isn't stretched but texture is not following geometry. It does not bend with it.
Which approach should I stick to?
Replies
Rectangular UVs are very good, we save UV space and we can tile the textures easily with no visible seams. The bad is that we can't use them always, and sometimes is faster and better to use the 2nd method, a simple unwrap (planar). In your case, that chunk can be perfectly mapped in a rectangular way, but if texels must be 1:1 and without distortion, forget it. All depends!
Hope it helps!
I think my main mistake was using the stretch overlay in Blender instead of angle overlay. With angle overlay it is now much more clear when to keep shape rectangular. I've also got AKM mode from ChamferZone tutorial. Checked his UV and he clearly rely on angle stretching. Most of it its blue, with some very bright blue in some areas. As this is my first so advanced model, I think that's also matters here cause if if I start doing it now, it geometry would be bette and propably easier for UV mapping.
One more question which I'am also wondering. I see that most of people don't triangulate their models in the 3ds software. With my model I've got some n-gons on flat surfaces, so it doesn't affect shading. I've decided to make at least quads where possible before UV unwrapping. That sometimes creates very long triangles (like with very long rectangle which has got fifth vert in the middle of the edge). Is that somehow matters for UV?
N-gons are not a problem in UVs. If you are doing a game model, triangulation is useful to control edge direction, and that's all.
For example, the cap of a cylinder, you can have a quad cap or the typical n-gon cap. Both cases are good in UV. What really matters is how good you do the unwrap, packing, and how good is your mesh with its seams. We can add more geo, but at the end, it's all up to us.
N-gons should not be an issue within our UV tools.