Unwraping a curved object (how I do)

[micheus]

How hard can be unwrap an object like this with AutoUV?


That is something I faced and tried to improve my strategies to use as less steps as possible and spend more time doing other things.
During the process, I fell like I could have did something before that could avoid the step I was doing at that moment. So, it's a subject full of options/approaches and I hope at the end someone else can share their ideas.

I'm going add the posts always I have time to prepare pictures and spend some time writing.

Today I'm going to leave a picture of my initial strategy so you guys can start think about that.


Initial considerations:
- I started with an object already done and I decided to improve it just after finish it (as I told here);
- I decided to not use symmetry, but that would have speeded up the things if I had planned that from the sketch. I didn't want start all again (lazy I know );

[micheus]

I started by the most laborious - the worst mesh segments to work:

Which one would you prefer to segment to unwrap?

I picked the right one even knowing I will subdivide the mesh in a next step and that cause some distortion on the texture.
But, because I added a short bevel (with Inset) I know the faces in the boundaries areas will not be so affected by the smooth and that should not be a problem.

[Marcin Maćkowiak]

Which one would you prefer to segment to unwrap?

Simple question - the left one. But as you said if we are going to smooth it in the future it is going to ruin the mesh. We can fix it with stretch optimization, but mesh won't be the same anymore.

Anyway there was a good suggestion somewhere on the forum to update a slide option so the slide don't change the uv projection same for move and smooth. So I guess there will be no question like that in the future

[micheus]

Thanks for get into this discussion.

Simple question - the left one. But as you said if we are going to smooth it in the future it is going to ruin the mesh. We can fix it with stretch optimization, but mesh won't be the same anymore.

I don't think it won't be the same


Note that I'm talking to unwrap in low mesh resolution the strip area. Everything else can be done in high resolution as usual.

Extract and organize the tine strips segments in low resolution can - at least - save half of the time you would spend if doing that after smooth the mesh.

In fact, it we are not going to use a 2D paint tool we could to segment it face by face and don't take much care about its arrangement. Although the texture image appearance would be a mess.

So I guess there will be no question like that in the future

Of course that kind of fix will help, but only to allow us to improve/add details to an already UVmapped object without mess up our previous work. That is not applied for when we create the UV map for the first time. We still will need a good way/strategy to unwrap the mesh.

[micheus]

Simple question - the left one. But as you said if we are going to smooth it in the future it is going to ruin the mesh. We can fix it with stretch optimization, but mesh won't be the same anymore.

I don't think it won't be the same

Just to put my comment in the right context, I'm taking about this kind of shape.

Continuing...

I create selections to define a macro segmentation in Geometry window (GW) and store them in Selection Groups window (SG). By using the options Union, Subtract and Intersect can help to select group of elements without have to do that "one-by-one" or do that carefully.

This strip will not have any kind of elements painted on it that needs to be oriented to its curvature. So, to save space, I'm going to make them straight lines.

The segmentation in AutoUV Segmenting window:

After unfolding (the left one). By using Edge mode for both Geometry and AutoUV window I select one edge loop in GW that I got all segments with one edge selected (the middle one) and then I used Rotate->Chart to Y in order to align them vertically (the right one).


Because I don't want the entire strip glued, in the GW I selected a segment of faces (the left one) to get them selected in the AutoUV and then I grouped these faces out of that confusion (the middle one). After that I selected one edge in each segment (the most horizontal one) and Stitch them (the right one):


I aligned the edges using Move->Horizontal (the left one) and after that I applied Flat->Y that aligned the vertices by the middle point. Then, by repeating the sequence of select some edges, mouse over GW, [ALT+L], back to AutoUV and Stitch I got the segment ready (the middle one). The result isn't so bad (the right one):

[micheus]

Before and after smooth once:


Here a example how I released the stretched faces and make it part of the other islands I create for the rest of the mesh:


For the rest of the mesh - as it's possible to observe in the image in the first post - I selected segments to minimize the curvature to be unwrapped. When I invoked the UV map [LMB] for these segments I did new cuts again minimizing the curved areas and then used Projection Normal to unwrap the mesh:

Each island was arranged to be closed to each other and the gaps were minimized by moving surrounding vertices and after the Stitch be applied I used Tighten to redistribute the vertex weight in the glued area.

[micheus]

Roadkill can help us to find the tension areas (red/blu - green is good) and I used it to localize and apply Tighten on those areas. It's impossible to get full green colors for curved mesh:


When everything seems to be OK it's time to select all islands (in Body mode) and use Scale->Normalize Sizes followed by Remap UV->Stretch Optimization.

[Marcin Maćkowiak]

Well done! I didn't know untill today how the Rotate->Chart to Y works, thanks to you!

[micheus]

Thanks Marcin Maćkowiak.

I forgot to mention. RoadKill is a UV Tool that we can download the standalone version (look for Maya in the page). We need to export a .OBJ to use with it.

I don't like much its selection tools, that is why I prefer to cut all the mesh in Wings3D. Most the time I load the .OBJ in RoadKill I've noticed Wings3D has been doing a good job unfolding the mesh - at least if I chose good segments to cut.