I havent done much uv work in maya. So far it have worked fine, I've been using automap and then stitching together parts what needs it. Now I tried new approach for mudguards (model seen before here in my last post)
I added cylindrical map because they are in cylindrical shape. Then I cutted the edges needed to unfold it and then I clicked unfold. It makes sense to me to get nice planar shape of mudguards and seams are there where I cutted. However the shape I get is weird and twisted for some reason. I have no idea why this is happening.
Again, I post a link to my dropbox folder because the picture is quite large to post here. There is on right side the uv after cylindrical map and before unfolding and on left side is unfolded map. Why is this strange bending happening?
This is happening because the back half of the geometry is facing the opposite direction from the front. This makes it difficult for Maya to figure out how to unwrap things; it's trying to unfold this stuff in 2D space when what's really needed is for the back to flip 180 degrees through 3D space to lie flat.
If I were you, I'd unwrap manually. Starting with the cylindrical-based map on the right of your image, cut all the way around the edge of the geo, then separate out the two shells and manually flip the back one left-to-right in UV space. Once you've done that, you should be able to stitch the two shells back together nicely along one edge if you want.
The 'unfold' tool is more commonly used for organic forms, like bodies with limbs. Geometric stuff tends to work better with projections and hand-tweaking.