Pivots are in a wrong positions after FBX import #104558

New Issue

Jesse Yurkovich · 2023-04-19T04:30:08+02:00

Jesse Yurkovich commented

2023-04-19 04:30:08 +02:00

System Information
Operating system: Windows-10-10.0.22621-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 531.61

Blender Version
Broken: version: 3.4.1, branch: blender-v3.4-release, commit date: 2022-12-19 17:00, hash: rB55485cb379f7
Worked: (newest version of Blender that worked as expected)

Short description of error

If you import this file in Blender pivots will be in the middle of the signs. but if you import this file in Unity or Maya pivots will be in the roots of objects. Down to the beginning of geometry.

I need the right import algorithm for Blender

Exact steps for others to reproduce the error

none listed

Note: This was copied from blender/blender#107029

**System Information** Operating system: Windows-10-10.0.22621-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 3070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 531.61 **Blender Version** Broken: version: 3.4.1, branch: blender-v3.4-release, commit date: 2022-12-19 17:00, hash: `rB55485cb379f7` Worked: (newest version of Blender that worked as expected) **Short description of error** If you import this file in Blender pivots will be in the middle of the signs. but if you import this file in Unity or Maya pivots will be in the roots of objects. Down to the beginning of geometry. I need the right import algorithm for Blender **Exact steps for others to reproduce the error** - none listed Note: This was copied from https://projects.blender.org/blender/blender/issues/107029

Road_signs_v1.FBX

328 KiB

Jesse Yurkovich added the

labels 2023-04-19 04:30:09 +02:00

Jesse Yurkovich referenced this issue from blender/blender

2023-04-19 04:31:20 +02:00

Pivots are in a wrong positions after FBX import #107029

Thomas Barlow commented

2023-04-19 16:40:29 +02:00

It just so happens that I'm looking into this area of the importer for a different issue at the moment.

This FBX file has Geometric Transforms defined for each Model (similar to Blender Object). It looks like Blender's FBX Importer transforms the Object by this amount, but I'm wondering if it should actually be transforming the Mesh data itself instead (Unity appears to do this). Transforming the Mesh data would make some sense of why Geometric Transforms are not inherited on child Objects. The FBX documentation notes that "[Geometric Transforms] relate to the object-offset concept in 3ds Max".

I added an Empty at the origin of one of the signs and then subtracted the GeometricTranslation (converted from FBX coordinates to Blender coordinates) and it goes to precisely where the pivot is expected to be in this issue.

I imagine that changing the importer to transform the Meshes by the Geometric Transforms and not the Objects could be done, but care would probably need to be taken if multiple Models (Blender Objects) can share the same Geometry (Blender Meshes), but have different Geometric Transforms, since this is not possible in Blender without duplicating the mesh or doing something different like inserting an Empty into the hierarchy to achieve the Geometric Transforms instead. Though, I'm not sure how this would work for Armatures/Cameras/etc., they might need to remain with the current behaviour.

As a sidenote, slightly weird FBX file, as it has both PreRotation (FBX SDK/Maya) and GeometricTranslation/GeometricRotation (3DSMax).

It just so happens that I'm looking into this area of the importer for a different issue at the moment. This FBX file has Geometric Transforms defined for each Model (similar to Blender Object). It looks like Blender's FBX Importer transforms the Object by this amount, but I'm wondering if it should actually be transforming the Mesh data itself instead (Unity appears to do this). Transforming the Mesh data would make some sense of why Geometric Transforms are not inherited on child Objects. The FBX documentation notes that "[Geometric Transforms] relate to the object-offset concept in 3ds Max". I added an Empty at the origin of one of the signs and then subtracted the `GeometricTranslation` (converted from FBX coordinates to Blender coordinates) and it goes to precisely where the pivot is expected to be in this issue. ![image](/attachments/2797d8a7-2c89-4fb5-b92e-6aef976f40c1) I imagine that changing the importer to transform the Meshes by the Geometric Transforms and not the Objects could be done, but care would probably need to be taken if multiple Models (Blender Objects) can share the same Geometry (Blender Meshes), but have different Geometric Transforms, since this is not possible in Blender without duplicating the mesh or doing something different like inserting an Empty into the hierarchy to achieve the Geometric Transforms instead. Though, I'm not sure how this would work for Armatures/Cameras/etc., they might need to remain with the current behaviour. As a sidenote, slightly weird FBX file, as it has both `PreRotation` (FBX SDK/Maya) and `GeometricTranslation`/`GeometricRotation` (3DSMax).

image.png

42 KiB

Thomas Barlow referenced this issue

2023-04-20 04:57:58 +02:00

FBX Import: Fix pre-, post- and geometric rotations #104561

Bastien Montagne referenced this issue from a commit

2023-04-28 17:21:52 +02:00

FBX Import: Fix pre-, post- and geometric rotations

Thomas Barlow referenced this issue

2023-07-19 14:35:55 +02:00

FBX Export doesn't maintain custom pivot locations. #104758

Thomas Barlow referenced this issue from blender/blender