Cineversity

Hello Cineversity,
I run into this error typically when working with a 3rd party 3D model.

— Normally I can “unwrap” and “relax” UV’s like this and get them in better shape.
BUT Sometimes C4D throws some goofy error - with no obvious easy solution.
-
Using a “frontal” projection as a starting point and trying to “relax” the UV’s and flatten them out.
“Relax UV Error
- UV-island has no proper boundary”

— The UV’s I end up with don’t represent the flattened shape and consequently render badly.
—Other unwraps works, but wreck any seamless texture with UV fragments.
— Mari, or zBrush seem like a missing requirement in my tool bag to remap, but taking the time out of the C4D workflow to switch apps, or remodel, or re-topo sucks time away from other things that I should be working on. - and that sorta defeats the purpose of the buying the stock 3D model.
QUESTION:
What would you do with this error type?
What do I do when C4D has an “unsolvable UV unwrap error?” 

—
There’s another error that plagues me occasionally too. I haven’t seen it in a while, so I forget what it is exactly. It’s basically causes a bunch of fiddling around.
—

Thanks in advance for your time.

Cheers,
jamie

Hi Jamie,

Thanks for the file, so much better to answer this. I opened it and it looked already like a problem file. Perfect example! Great share! So, lets inspect this. (I have recorded some steps, see the link below) Some ideas or suggestions might be not really working here, but perhaps they are worth mentioning for other projects.

The first thing that I always do, when a problem is given, checking the mesh.
Typically the Normals, especially in 3rd party models, are off. Same here.
Normally you can fix this quickly with the Mesh>Normals> [see options]

The second part is to check the polygons itself. Are they OK, connected, or even un-usable, etc?
In R17 we have now a new tool for that: Mesh>Commands>Modeling Settings. Problem areas become faster visible.
If there is a quick fix is certainly a longer discussion …

In UV-Edit, the first idea would be the UV Peeler, but the “holes” in the given model will prevent that.

The Island problem, is given when there is no option to un-wrap it. An island is a certain amount of connected UV Polygons. If you take a plane object then you can easily predict where the coast of that island is. If you take a sphere, then you have no “natural” coast/beach. An example would be like peeling an orange, you need to break the peel at one point to do that, and that break must be large enough. So, speaking of UV peeling we need to introduce a cut/seam, so we get a “coast” to that island. In the Relax part of the UV Mapping>Relax UV you find an option to use an “Edge Selection” to specify this cut. Tutorials are available for this procedure. Edge Selections for all the holes might be not really a nice work to do, thought.

If you get an error, and the mesh is OK, and the mesh can be peeled, then select half of the mesh, relax it, no problem, then it is in the other half. Select a half of this and so on. You might be surprised how fast to get to the problem in this way.

Given the Curtain as the example file, what would I do?
https://www.amazon.com/clouddrive/share/bSuTh0sDSjlydgs2IZi9gAehCYHE1TCLjUuDP7YeEXw?ref_=cd_ph_share_link_copy
note that I do not fix the hole polygons, as that is not the problem here, but they need attention!  [you can download this]

I would select one side of the curtain, just enough to get a thin model from it, not the “Extruded Version”. Then fix the problems around the holes (I would check if an Alpha map hole would be possible!). Since the mesh intersected before, that reduction first seems a good idea anyway. This can be then easily relaxed. To get a “volume” object back then, this could be done with a single Simulate>Cloth Surface set to a a certain Thickness. UV stays stable then. Cloth allows only one side texturing, not Front and Back [Texture Tag]. To make that possible, one needs to make this editable and go from there.

All the best

Video with some alternative steps. [you can download this]
https://www.amazon.com/clouddrive/share/IsG2NeCv4fBB4yU92nRGpeUCVGqfRzv2Orvr1RBJQvF?ref_=cd_ph_share_link_copy

Again, it contains suggestions and ideas, perhaps not suitable for this object, but perhaps helpful anyway. Of course—I tried to stay focused on you curtain.

P.S.:

Perhaps a useful sequence of information is this list I have put together for you
First to see some key features, which will be explored more “hands on” in the four part series.
(Some might go the other way around)
http://www.cineversity.com/vidplaytut/bodypaint_3.5_relax_uv_enhancements
http://www.cineversity.com/vidplaytut/uv_manager_relax

Then, more detailed, the four part series.
http://www.cineversity.com/vidplaylist/uv_-_relax_and_unwrap/relax_uv_command_before_you_begin
http://www.cineversity.com/vidplaylist/uv_-_relax_and_unwrap/relax_uv_command_introduction
http://www.cineversity.com/vidplaylist/uv_-_relax_and_unwrap/relax_uv_command_part_i
http://www.cineversity.com/vidplaylist/uv_-_relax_and_unwrap/relax_uv_command_part_ii

There are many more tutorials on UV(W), but I guess these are the best fit to your question.

Jamie, you mentioned re-modeling, but as you mentioned—too much extra-work defeats the idea. Well, that is a case to case decision from my point of view.

My thoughts about this, if you buy anything of real value, the UV and the mesh should be usable—directly. anything else cut into your time, and into the project time. Which can become costly.

I agree with you, if re-modeling, or modeling newly takes as long as fixing the 3rd part model and getting the UV to work, makes no sense. On the end, all the work put into a 3rd party model end up, that you have something other people may use. Not nice—from where I look at it.

The curtain could have been done easily in MoGraph, as usually, I do this to prove the point. Which is kind of a simple set up, and you have a lot of option to adjust a lot to you liking. I know, this is not about a curtain, but each case needs a new evaluation of course. At least the UV is as easy to adjust as possible ;o)

My best wishes.

https://www.amazon.com/clouddrive/share/o5CzcY8DfagY5yoEnKVywExcMgABqVuZ3SI5SXPLnur?ref_=cd_ph_share_link_copy

Thanks Doctor!

You’re welcome, Jamie!

My best wishes!