Bone offset between Rest Pose and Edit mode #46010

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Juan Pablo Bouza · 2015-09-04T01:03:28+02:00

Juan Pablo Bouza commented

2015-09-04 01:03:28 +02:00

In the blend file you'll find two bones that in edit mode are perfectly overlapped but in pose mode they have an offset, even if the rig is in Rest Position.

The only reason I find for this to happen is the use of the "Apply Pose as Rest Pose" operator. If you run that operator multiple times you'll notice that the offset between the two bones gets even worse.

Even though the Apply Pose operator could be the cause of this undesirable offset, I've found out that this started to happen only after blender 2.71. If you open the file with Blender 2.70a, you'll see that if you toggle between Pose mode and Edit mode, the offset is fixed!!

apply_pose_bug.blend

In the blend file you'll find two bones that in edit mode are perfectly overlapped but in pose mode they have an offset, even if the rig is in Rest Position. The only reason I find for this to happen is the use of the "Apply Pose as Rest Pose" operator. If you run that operator multiple times you'll notice that the offset between the two bones gets even worse. Even though the Apply Pose operator could be the cause of this undesirable offset, I've found out that this started to happen only after blender 2.71. If you open the file with Blender 2.70a, you'll see that if you toggle between Pose mode and Edit mode, the offset is fixed!! [apply_pose_bug.blend](https://archive.blender.org/developer/F230159/apply_pose_bug.blend)

Juan Pablo Bouza commented

2015-09-04 01:03:28 +02:00

Changed status to: 'Open'

Joshua Leung was assigned by Juan Pablo Bouza

2015-09-04 01:03:28 +02:00

Juan Pablo Bouza commented

2015-09-04 01:03:28 +02:00

Added subscriber: @jpbouza-4

perfection cat commented

2015-09-04 02:49:51 +02:00

Added subscriber: @sindra1961

perfection cat commented

2015-09-04 02:49:51 +02:00

Can you show a method to let it reappear in armature of simpler structure?
I can confirm a reported phenomenon, but do not understand a concrete procedure to produce it.
For example, can you reproduce it in Armature with three bone?

Can you show a method to let it reappear in armature of simpler structure? I can confirm a reported phenomenon, but do not understand a concrete procedure to produce it. For example, can you reproduce it in Armature with three bone?

Juan Pablo Bouza commented

2015-09-04 03:17:56 +02:00

Mmmm, no actually I don't know of a method to do so. Some time ago I spoke to Zanqdo about this and he also told me that he had seen such behavior with the Apply Pose operator, like if it messed up some things.

I just tried with a simple armature and it didn't happen, I wouldn't know how to reproduce this.

Anyway, I have the feeling that the solution for this is in the 2.70a to 2.71 transition. As I said, if you open the armature in 2.70a or previous versions, Blender automatically fixes the issue when toggling Edit Mode. So, my guess is that in those versions of Blender there were some kind of checks that didn't let Pose mode to be different from Edit mode... but well I'm just guessing here.

Mmmm, no actually I don't know of a method to do so. Some time ago I spoke to Zanqdo about this and he also told me that he had seen such behavior with the Apply Pose operator, like if it messed up some things. I just tried with a simple armature and it didn't happen, I wouldn't know how to reproduce this. Anyway, I have the feeling that the solution for this is in the 2.70a to 2.71 transition. As I said, if you open the armature in 2.70a or previous versions, Blender automatically fixes the issue when toggling Edit Mode. So, my guess is that in those versions of Blender there were some kind of checks that didn't let Pose mode to be different from Edit mode... but well I'm just guessing here.

perfection cat commented

2015-09-04 03:50:41 +02:00

bone of the parent of two bone which you pointed out is different.
It shows that it is arranged based on a different coordinate system.
If you change connected of bone of the parent of bad_offset-bone to ON, this phenomenon does not occur.
I do not know whether this is a thing by the difference in version of blender.

bone of the parent of two bone which you pointed out is different. It shows that it is arranged based on a different coordinate system. If you change connected of bone of the parent of bad_offset-bone to ON, this phenomenon does not occur. I do not know whether this is a thing by the difference in version of blender.

Juan Pablo Bouza commented

2015-09-04 04:22:20 +02:00

Oh man I'm so sorry, I thought I had deleted the rest of the bones!!!

Ok, here it is, new blend "apply_pose_bug_2", just 4 bones. No constraints or drivers or anything. The hierarchy is as follows:

1 parent of 2. 2 parent of bad_offset.

Now, the problem is still there, although I noticed something important... If you move 1 or 2 in Edit mode, the offset changes. It seems that when you move them closer to bad_offset, the offset decreases....

I know that this is a pain, cause it's something you cannot reproduce, but this armature is definitely bugged in 2.71+ and it wasn't in previous releases.

apply_pose_bug_2.blend

Oh man I'm so sorry, I thought I had deleted the rest of the bones!!! Ok, here it is, new blend "apply_pose_bug_2", just 4 bones. No constraints or drivers or anything. The hierarchy is as follows: 1 parent of 2. 2 parent of bad_offset. Now, the problem is still there, although I noticed something important... If you move 1 or 2 in Edit mode, the offset changes. It seems that when you move them closer to bad_offset, the offset decreases.... I know that this is a pain, cause it's something you cannot reproduce, but this armature is definitely bugged in 2.71+ and it wasn't in previous releases. [apply_pose_bug_2.blend](https://archive.blender.org/developer/F230193/apply_pose_bug_2.blend)

perfection cat commented

2015-09-04 08:32:25 +02:00

I calculated a position of bone in pose mode, but values seem to be different.

2.75(sub4)
== Pose ==
[bad_offset] world location: 0.59950 -0.01245 1.10259
[good] world location: 0.59950 -0.01245 1.10259

2.70a
== Pose ==
[bad_offset] world location: 0.59858 -0.01245 1.10260
[good] world location: 0.59858 -0.01245 1.10260

2.75(sub4)

2.70a

I attach the script which I used for calculation.
calc.py
The position that slid seems to be right by the calculation.

I calculated a position of bone in pose mode, but values seem to be different. ``` 2.75(sub4) == Pose == [bad_offset] world location: 0.59950 -0.01245 1.10259 [good] world location: 0.59950 -0.01245 1.10259 2.70a == Pose == [bad_offset] world location: 0.59858 -0.01245 1.10260 [good] world location: 0.59858 -0.01245 1.10260 ``` 2.75(sub4) ![275.png](https://archive.blender.org/developer/F230236/275.png) 2.70a ![270a.png](https://archive.blender.org/developer/F230238/270a.png) I attach the script which I used for calculation. [calc.py](https://archive.blender.org/developer/F230243/calc.py) The position that slid seems to be right by the calculation.

Bastien Montagne commented

2015-09-04 10:22:57 +02:00

Added subscriber: @mont29

Bastien Montagne commented

2015-09-04 10:22:57 +02:00

Actually, it’s 3Ddrawing of non-parrented bone ('good') and editmode which is bad - if you place 3DCursor on head of those, you get x = 0.59858, when head of those bones (as reported by their matrix) is x = 0.59950…

I would suspect some issue with our 'minimum bone length' enforcing (we do not allow zero-lenght bones), since diff seems to be only along X axis, which is also orientation of the parent "2" bone, a very short one.

Actually, it’s 3Ddrawing of non-parrented bone ('good') and editmode which is bad - if you place 3DCursor on head of those, you get `x = 0.59858`, when head of those bones (as reported by their matrix) is `x = 0.59950`… I would suspect some issue with our 'minimum bone length' enforcing (we do not allow zero-lenght bones), since diff seems to be only along X axis, which is also orientation of the parent "2" bone, a very short one.

Joshua Leung was unassigned by Bastien Montagne

2015-09-04 10:23:09 +02:00

Bastien Montagne self-assigned this 2015-09-04 10:23:09 +02:00

Bastien Montagne commented

2015-09-04 10:23:09 +02:00

Added subscriber: @JoshuaLeung

Bastien Montagne commented

2015-09-04 10:54:00 +02:00

Ok, can confirm this is the shortness of bone "2" which is causing that issue - in Edit mode, move its tail along X axis by -0.002 and its child matches expected position nearly perfectly (the longer you make bone "2", the smaller the gap).

I’m going to see whether we can aliviate that, but afraid this will be just another float precision issue… :/

Ok, can confirm this is the shortness of bone "2" which is causing that issue - in Edit mode, move its tail along X axis by `-0.002` and its child matches expected position nearly perfectly (the longer you make bone "2", the smaller the gap). I’m going to see whether we can aliviate that, but afraid this will be just another float precision issue… :/

Juan Pablo Bouza commented

2015-09-04 15:35:56 +02:00

Bastien, but why is this corrected by 2.70a? At least from a user point of view

So, what do 2.70a and previous versions do differently from 2.71+ ?

Bastien, but why is this corrected by 2.70a? At least from a user point of view So, what do 2.70a and previous versions do differently from 2.71+ ?

Juan Pablo Bouza commented

2015-09-04 15:56:52 +02:00

Mmmm well I don't know if this helps but if you unparent 2 from 1, the offset is solved.

Also, I tried changing bone 2 values and I can say that if you perfectly align head and tail, the offset if gone. Well, the same happens if you rotate the bone randomly, at some positions there is no offset. Ok, this could be related to floating precision as Bastien says, but again, I don't understand why 2.70 doesn't have the issue. Really, I had never seen this inconsistencies between Edit mode and the armature in Rest Position before 2.71.

Mmmm well I don't know if this helps but if you unparent 2 from 1, the offset is solved. Also, I tried changing bone 2 values and I can say that if you perfectly align head and tail, the offset if gone. Well, the same happens if you rotate the bone randomly, at some positions there is no offset. Ok, this could be related to floating precision as Bastien says, but again, I don't understand why 2.70 doesn't have the issue. Really, I had never seen this inconsistencies between Edit mode and the armature in Rest Position before 2.71.

blender-admin commented

2015-09-04 16:50:29 +02:00

This issue was referenced by 65a80708d4

This issue was referenced by 65a80708d4ca0d28a9c6e35bf7429693b806e0b4

Bastien Montagne commented

2015-09-04 16:50:57 +02:00

Changed status from 'Open' to: 'Resolved'

Bastien Montagne closed this issue

2015-09-04 16:50:57 +02:00

Bastien Montagne commented

2015-09-04 16:53:54 +02:00

Found issue and fixed - my bet re 2.70 would be that we were handling roll nightmare differently by that time iirc - yes, all our Armature issues are related to demonic bone roll one way or the other, it seems. :(

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Bone offset between Rest Pose and Edit mode #46010