Baking euler rotation to quaternions error #71924

New Issue

Maciej Szcześnik · 2019-11-26T11:53:33+01:00

Maciej Szcześnik commented

2019-11-26 11:53:33 +01:00

System Information
Operating system: Windows 10 64 bit
Graphics card: nVidia 970 GTX

Blender Version
Broken: 2.81, master,

Short description of error
When one bakes an object with Euler rotations to an object with quaternion rotations, the baked quaternions are "mirrored", meaning that every time the rotation exceeds 360 degrees, the quaternion W and respective rotation axis will be inverted. It produces the same visual result but introduces a lot of problems (with smoothing for instance).

You can find the original Euler rotation below (720 degrees along the Z-axis):

{F8168303,size=full}

And here is the baked quaternion rotation (the same 720 degrees along the Z-axis, baked from the cube using Euler rotations):

{F8168330, size=full}

And here is how the properly baked quaternion rotations should look like - these are adjusted by hand (with such curves there would be no problems with smoothing, etc.):

{F8168341, size=full}

Why this is important? If one works with FBX rigs, imports and exports FBX animations it becomes very problematic very soon. FBX rigs contain only Euler animations and importing an FBX rig to Blender bakes the animations onto an armature with quaternion rotations. This "inverted" curves problem appears for every bone that rotates more than 360 degrees. It is possible to go an fix the errors one by one manually, but I guess it could be fixed by the baker automatically, making the life of a game animator a lot easier :).

Exact steps for others to reproduce the error
Blender bake error.blend

Please open the attached file.
You will find 3 cubes - the blue one uses Euler animation and rotates 720 degrees in the Z-axis. The green one copies the rotations with a constraint but uses quaternion rotations. The red one is the same as the green one but has the animation already baked and constraints removed for your convenience.
You can select the green cube, press F3, type Bake.
Choose Bake Action.
Set the Start Frame to 1 and the End Frame to 100.
Check the Visual Keying and the Clear Constraints options.
Make sure to check the Object Bake Data.
Hit OK.
Navigate to the Graph Editor and observe the baked curve.

Please consider addressing this bug as it will make Blender more industry-standard in terms of animations - especially when working with FBX data.

Have a nice day,
Maciej

**System Information** Operating system: Windows 10 64 bit Graphics card: nVidia 970 GTX **Blender Version** Broken: 2.81, master, **Short description of error** When one bakes an object with Euler rotations to an object with quaternion rotations, the baked quaternions are "mirrored", meaning that every time the rotation exceeds 360 degrees, the quaternion W and respective rotation axis will be inverted. It produces the same visual result but introduces a lot of problems (with smoothing for instance). You can find the original Euler rotation below (720 degrees along the Z-axis): {[F8168303](https://archive.blender.org/developer/F8168303/image.png),size=full} And here is the baked quaternion rotation (the same 720 degrees along the Z-axis, baked from the cube using Euler rotations): {[F8168330](https://archive.blender.org/developer/F8168330/image.png), size=full} And here is how the properly baked quaternion rotations should look like - these are adjusted by hand (with such curves there would be no problems with smoothing, etc.): {[F8168341](https://archive.blender.org/developer/F8168341/image.png), size=full} Why this is important? If one works with FBX rigs, imports and exports FBX animations it becomes very problematic very soon. FBX rigs contain only Euler animations and importing an FBX rig to Blender bakes the animations onto an armature with quaternion rotations. This "inverted" curves problem appears for every bone that rotates more than 360 degrees. It is possible to go an fix the errors one by one manually, but I guess it could be fixed by the baker automatically, making the life of a game animator a lot easier :). **Exact steps for others to reproduce the error** [Blender bake error.blend](https://archive.blender.org/developer/F8168280/Blender_bake_error.blend) 1. Please open the attached file. 2. You will find 3 cubes - the blue one uses Euler animation and rotates 720 degrees in the Z-axis. The green one copies the rotations with a constraint but uses quaternion rotations. The red one is the same as the green one but has the animation already baked and constraints removed for your convenience. 3. You can select the green cube, press F3, type Bake. 4. Choose Bake Action. 5. Set the Start Frame to 1 and the End Frame to 100. 6. Check the Visual Keying and the Clear Constraints options. 7. Make sure to check the Object Bake Data. 8. Hit OK. 9. Navigate to the Graph Editor and observe the baked curve. Please consider addressing this bug as it will make Blender more industry-standard in terms of animations - especially when working with FBX data. Have a nice day, Maciej

Maciej Szcześnik commented

2019-11-26 11:53:33 +01:00

Added subscriber: @MaciejSzczesnik