FBX Exporter: vertices exported in incorrect position causing mesh deformation #61860

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opened 2019-02-22 22:34:27 +01:00 by Tsuna Hiiragi · 14 comments

System Information
Operating system: Windows 10 x64
Graphics card: RTX 2070

Blender Version
Broken: 2.79, 2.8

Short description of error
When skinned meshes are exported with FBX 7.4 binary the position of vertices does not export correctly.
As a result meshes are deformed (visible but not extreme in most cases) after export.

Note that external tools/software may be required to compare the meshes as the bug may be invisible upon re-import to blender.
A good way to see the differences is to use the mesh wireframe in iso view in blender versus unity for example.

Comparison of before and after in sample case (Click to load gif)
2019-02-21_19-57-26.gif

Exact steps for others to reproduce the error

  1. Load the attached blend file.
    testcase.blend
  2. Export to FBX using 7.4 binary
  3. Compare the position of vertices before and after export.
**System Information** Operating system: Windows 10 x64 Graphics card: RTX 2070 **Blender Version** Broken: 2.79, 2.8 **Short description of error** When skinned meshes are exported with FBX 7.4 binary the position of vertices does not export correctly. As a result meshes are deformed (visible but not extreme in most cases) after export. **Note that external tools/software may be required to compare the meshes as the bug may be invisible upon re-import to blender.** A good way to see the differences is to use the mesh wireframe in iso view in blender versus unity for example. Comparison of before and after in sample case (*Click to load gif*) ![2019-02-21_19-57-26.gif](https://archive.blender.org/developer/F6690022/2019-02-21_19-57-26.gif) **Exact steps for others to reproduce the error** 1. Load the attached blend file. [testcase.blend](https://archive.blender.org/developer/F6690018/testcase.blend) 2. Export to FBX using 7.4 binary 3. Compare the position of vertices before and after export.
Author

Added subscriber: @Tsuna

Added subscriber: @Tsuna

Added subscriber: @goayakla

Added subscriber: @goayakla

Added subscriber: @ZedDB

Added subscriber: @ZedDB

I can't reproduce this on re-import into blender.

If blender imports the generated file, that means that at least to blender, the positions does not change.
There is not much we can do with simply "it doesn't import correctly in other program".

I can't reproduce this on re-import into blender. If blender imports the generated file, that means that at least to blender, the positions does not change. There is not much we can do with simply "it doesn't import correctly in other program".
Author

It may be difficult to see in blender on its own but this is a significant issue as you can not trust blenders export.
This means that the model is deformed in unity, unreal etc when it has been exported from blender (and only from blender).

It's a big deal when any kind of precision is needed.

It may be difficult to see in blender on its own but this is a significant issue as you can not trust blenders export. This means that the model is deformed in unity, unreal etc when it has been exported from blender (and only from blender). It's a big deal when any kind of precision is needed.

Added subscriber: @mont29

Added subscriber: @mont29

@mont29 can you reproduce this?

@mont29 can you reproduce this?

No, cannot reproduce, but I don’t have access to Unity or UE currently.

Re-importing into Blender works as expected, so geometry itself is definitively not altered, issue likely comes from the rigging (binding matrices and all that). Although I would still find it odd that this shows in some other app but not in Blender. FBX works in mysterious ways… :(

No, cannot reproduce, but I don’t have access to Unity or UE currently. Re-importing into Blender works as expected, so geometry itself is definitively not altered, issue likely comes from the rigging (binding matrices and all that). Although I would still find it odd that this shows in some other app but not in Blender. FBX works in mysterious ways… :(
Author

{F7651610}So I found a semi viable workaround which is to set pose to rest position until the issue was small enough. This can take anywhere between 1 to 30 attempts. However due to some changes in 2.8 this is not possible anymore.
The mesh always exports in the exact same state. However the incorrect positioning of the verts is more major in 2.8

See attached a testcase for 2.8

{[F7651610](https://archive.blender.org/developer/F7651610/testcase28.blend)}So I found a semi viable workaround which is to set pose to rest position until the issue was small enough. This can take anywhere between 1 to 30 attempts. However due to some changes in 2.8 this is not possible anymore. The mesh always exports in the exact same state. However the incorrect positioning of the verts is more major in 2.8 See attached a testcase for 2.8

Added subscriber: @iss

Added subscriber: @iss

Changed status from 'Confirmed' to: 'Needs User Info'

Changed status from 'Confirmed' to: 'Needs User Info'

I have re-triaged this report and can not reproduce it.
Can you please check if this is still an issue in latest build?
https://builder.blender.org/download/

I have re-triaged this report and can not reproduce it. Can you please check if this is still an issue in latest build? https://builder.blender.org/download/
Author

@iss Tested with 2.83 Alpha .
Able to reproduce the issue.
For safety i also tried entering pose mode and applying pose to rest.
Same result as previously.

Verified in 3dsMax 2020, Unity 2019.2.4 and Unity 2017.4.28<
The incorrect deformation is identical in all 3 instances.

#61860-reproduced-2-83a.jpg

@iss Tested with 2.83 Alpha . Able to reproduce the issue. For safety i also tried entering pose mode and applying pose to rest. Same result as previously. Verified in 3dsMax 2020, Unity 2019.2.4 and Unity 2017.4.28< The incorrect deformation is identical in all 3 instances. ![#61860-reproduced-2-83a.jpg](https://archive.blender.org/developer/F8345330/T61860-reproduced-2-83a.jpg)

Changed status from 'Needs User Info' to: 'Confirmed'

Changed status from 'Needs User Info' to: 'Confirmed'
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Reference: blender/blender-addons#61860
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