UV Transfer #44522

New Issue

francoisgfx · 2015-04-27T16:26:07+02:00

francoisgfx commented

2015-04-27 16:26:07 +02:00

System Information
Linux RedHat

Blender Version
version 2.73

Short description of error
Transfer UVs from Object A to B are not quite correct. I have tried several combination, still no way to fix it.
I managed to reproduce the bug with Suzanne since I cannot share our mesh which is under NDA. Yet our more complex mesh have way more trouble, but looks the same as below so far
Source :

Destination (transfered UV) :

Exact steps for others to reproduce the error

Duplicate Object A into Object B
Delete half of Object B
Create seams on Object B
Unwrap Object B
Add Mirror Modifier to Object B
Apply Mirror Modifier (make sure there is same amount of vertex and faces as Object A)
Move the Mirrored UV next to each other (move, scale, ...)
Select Object A then Object B
Press CTRL+Shift+T
Best result in most cases is with the following settings and give the above results :

**System Information** Linux RedHat **Blender Version** version 2.73 **Short description of error** Transfer UVs from Object A to B are not quite correct. I have tried several combination, still no way to fix it. I managed to reproduce the bug with Suzanne since I cannot share our mesh which is under NDA. Yet our more complex mesh have way more trouble, but looks the same as below so far Source : ![uv_source.jpg](https://archive.blender.org/developer/F167318/uv_source.jpg) Destination (transfered UV) : ![transfered_UV.jpg](https://archive.blender.org/developer/F167320/transfered_UV.jpg) **Exact steps for others to reproduce the error** - Duplicate Object A into Object B - Delete half of Object B - Create seams on Object B - Unwrap Object B - Add Mirror Modifier to Object B - Apply Mirror Modifier (make sure there is same amount of vertex and faces as Object A) - Move the Mirrored UV next to each other (move, scale, ...) - Select Object A then Object B - Press CTRL+Shift+T - Best result in most cases is with the following settings and give the above results : ![transferUV_param.jpg](https://archive.blender.org/developer/F167322/transferUV_param.jpg)

francoisgfx commented

2015-04-27 16:26:07 +02:00

Changed status to: 'Open'

francoisgfx commented

2015-04-27 16:26:07 +02:00

Added subscriber: @francois.register

francoisgfx commented

2015-04-27 16:30:22 +02:00

oups didn't finished to write the ticket (ctrl+enter trap)
Here is the attached file done with Suzanne.
transferUV_bug.blend

For now I have to do this process in Maya instead of Blender.

oups didn't finished to write the ticket (ctrl+enter trap) Here is the attached file done with Suzanne. [transferUV_bug.blend](https://archive.blender.org/developer/F167324/transferUV_bug.blend) For now I have to do this process in Maya instead of Blender.

francoisgfx commented

2015-04-27 16:31:14 +02:00

Added subscriber: @CedricPAILLE

Bastien Montagne was assigned by Sergey Sharybin

2015-04-28 09:46:12 +02:00

Sergey Sharybin commented

2015-04-28 09:46:12 +02:00

Added subscribers: @mont29, @Sergey

Sergey Sharybin commented

2015-04-28 09:46:12 +02:00

@mont29, correct me if i'm wrong, but think it's related on your transfer tools?

Bastien Montagne commented

2015-04-28 11:12:35 +02:00

Yes it its… and Think I know what’s happening - Even though we have several UV islands, there are no seams in the middle of that source mesh…

I didn’t wanted/though we'd have to implement UV Islands detections without seams, but look like it will be needed :(

There's also another issue here - the two faces generating the glitch are perfectly coplanar (they have the same normal), which breaks the 'select nearest corner from best matching face by normal' process).

So all in all, this is not really a bug, more like a TODO to enhance algorithms behind that feature - will have a look at it, but this is quite complex topic… :|

Yes it its… and Think I know what’s happening - Even though we have several UV islands, there are no seams in the middle of that source mesh… I didn’t wanted/though we'd have to implement UV Islands detections without seams, but look like it will be needed :( There's also another issue here - the two faces generating the glitch are perfectly coplanar (they have the same normal), which breaks the 'select nearest corner from best matching face by normal' process). So all in all, this is not really a bug, more like a TODO to enhance algorithms behind that feature - will have a look at it, but this is quite complex topic… :|

francoisgfx commented

2015-04-28 13:12:25 +02:00

I can confirm that we do have coplanar faces in our production mesh.
if we do add seams on each island and use a different transfer mode, would that work ?

I can confirm that we do have coplanar faces in our production mesh. if we do add seams on each island and use a different transfer mode, would that work ?

Bastien Montagne commented

2015-04-28 14:01:27 +02:00

Seams will help, but won't fix all issues - what happens with coplanar faces is that, once nearest vertex is found, code cannot currently decide which face (and hence face corner) is best, since they both have same normal. I need to add a sensible fallback stuff here (like mere "nearest face among all 'same normals' candidates").

Bastien Montagne commented

2015-04-28 15:55:33 +02:00

Ok, will commit a fix that addresses the 'coplanar faces' issue (basically, when a same vertex has several coplanar faces, the source face to use is choosen as nearest one from dest face).

Note however that with seams in the right place, 'interpolated' option for face corners' mapping do work too with existing code.

For now, we decided to only use edge seams to detect UV islands. This has of course some limitations, but it mostly means we can use the same UV islands data for all UVMaps, instead of having to generate one for each map…

Ok, will commit a fix that addresses the 'coplanar faces' issue (basically, when a same vertex has several coplanar faces, the source face to use is choosen as nearest one from dest face). Note however that with seams in the right place, 'interpolated' option for face corners' mapping do work too with existing code. For now, we decided to only use edge seams to detect UV islands. This has of course some limitations, but it mostly means we can use the same UV islands data for *all* UVMaps, instead of having to generate one for each map…

blender-admin commented

2015-04-28 16:01:43 +02:00

This issue was referenced by 34abe82205

This issue was referenced by 34abe82205995d6dab316e1c17b81f72358e7341

Bastien Montagne commented

2015-04-28 16:06:03 +02:00

Changed status from 'Open' to: 'Resolved'

Bastien Montagne closed this issue

2015-04-28 16:06:03 +02:00

Bastien Montagne commented

2015-04-28 16:06:03 +02:00

Closed by commit 34abe82205.

Closed by commit 34abe82205.

blender-admin commented

2015-04-28 19:12:30 +02:00

This issue was referenced by 3074bf0a71736413fb1b1c8323755110cfdd99be

francoisgfx commented

2015-07-03 14:43:14 +02:00

Changed status from 'Resolved' to: 'Open'

francoisgfx reopened this issue

2015-07-03 14:43:14 +02:00

francoisgfx commented

2015-07-03 14:43:14 +02:00

We did encounter some new issues.
I sent the files to Bastien, and asked me to update the ticket.

We tested the transfert both in Blender and Maya (where all cases worked fine). You can find the files in the attachment. We do believe that Maya does test the mirror to see if it finds a match.

Also the file transfert_UVs_001.blend return the following error "Error: Source and destination meshes do not have the same amount of face corners, 'Topology' mapping cannot be used in this case" while the stats (vertex, faces, edges,...) are exactly the same.
(Bastien already explained to me why it does this)

transfert_uvs.zip

cheers

F.

We did encounter some new issues. I sent the files to Bastien, and asked me to update the ticket. We tested the transfert both in Blender and Maya (where all cases worked fine). You can find the files in the attachment. We do believe that Maya does test the mirror to see if it finds a match. Also the file transfert_UVs_001.blend return the following error "Error: Source and destination meshes do not have the same amount of face corners, 'Topology' mapping cannot be used in this case" while the stats (vertex, faces, edges,...) are exactly the same. (Bastien already explained to me why it does this) [transfert_uvs.zip](https://archive.blender.org/developer/F200102/transfert_uvs.zip) cheers F.

Bastien Montagne commented

2015-07-03 14:52:32 +02:00

Changed status from 'Open' to: 'Resolved'

Bastien Montagne closed this issue

2015-07-03 14:52:32 +02:00

Bastien Montagne commented

2015-07-03 14:52:32 +02:00

@francois.register please do not reopen fixed tasks, issues reported here have been fixed. New issues need new tasks (remember, one issue per thread). :)

@francois.register please do not reopen fixed tasks, issues reported here *have been fixed*. New issues need new tasks (remember, one issue per thread). :)

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UV Transfer #44522