Maniphest T90125

Some Bones get slightly offset from Binding/Edit pose in Pose/Object mode
Confirmed, Normal
Actions

Assigned To
None
Authored By
Konstantins Visnevskis (kivig)
Jul 25 2021, 4:03 PM
Tags
  • BF Blender
  • Animation & Rigging
Subscribers
Konstantins Visnevskis (kivig)
Philipp Oeser (lichtwerk)

Description

System Information
Operating system: Linux-5.8.0-59-generic-x86_64-with-glibc2.31 64 Bits
Graphics card: GeForce GTX 560/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 390.143

Blender Version
Broken: version: 2.93.1, branch: master, commit date: 2021-06-22 05:57, hash: rB1b8d33b18c2f

Short description of error
As per usual procedure of chasing out rigged character twitches (rest pose differences from edit pose), I've stumbled upon one that seems to have nothing but bone configuration as the source.
Chain of Bones in particular coordinates produces an offset at the last bone tail when switching to/from edit mode (constraints/animation erased).
It was a longer bone chain but those not affecting the result were deleted.
Recreating bones from scratch in identical coordinates/rolls produced the same offset but in another direction.
Calculation precision insufficiency?

Exact steps for others to reproduce the error

stretch1.blend3 MBDownload

  • Open,
  • Switch to/from Edit/Pose or Edit/Object modes.

Related Objects

Event Timeline

Konstantins Visnevskis (kivig) renamed this task from Bone precision? to Bones get slightly offset from Binding/Edit pose in Pose/Object mode.Jul 25 2021, 4:03 PM
Konstantins Visnevskis (kivig) created this task.
Konstantins Visnevskis (kivig) renamed this task from Bones get slightly offset from Binding/Edit pose in Pose/Object mode to Some Bones get slightly offset from Binding/Edit pose in Pose/Object mode.Jul 25 2021, 4:07 PM
Konstantins Visnevskis (kivig) updated the task description.
Philipp Oeser (lichtwerk) changed the task status from Needs Triage to Confirmed.Sep 27 2021, 2:28 PM
Philipp Oeser (lichtwerk) added a project: Animation & Rigging.
Philipp Oeser (lichtwerk) added a subscriber: Philipp Oeser (lichtwerk).

Can confirm this one.
This goes away when Inherit Rotation is unchecked on that specific bone (that is probably clear - just pointing out since clearing rotation on all bones makes no difference)

Konstantins Visnevskis (kivig) added a comment.EditedDec 3 2021, 12:10 PM

Found one more. The offset is larger, and is magnified even more (possibly happening more times in a row) on the complete rig, resulting in about 2-3mm foot offset on a cat, which is a visible transformation.
The offset seems to decrease when bone spine_fk.001 is not as close to horizontal (in Edit Mode) and disappears when it gets completely horizontal, suggesting possible calculation precission insufficiency.

bones.blend1 MBDownload

Konstantins Visnevskis (kivig) mentioned this in T96166: Insufficient transform precision?.Mar 4 2022, 2:43 PM