HumanPose bodyPosition (center of mass) is drifting away when moving avatar away from origin

In our application, we are using the human pose of the animator to retarget avatar movements from a source avatar (provided by mocap) to our target avatars. I was wondering that source and target characters are drifting away from each other when leaving the origin of the tracking system.

So I did some tests with the human pose and found that the bodyPosition (center of mass) provided by the HumanPose does not represent the avatar's position. In the following video, I visualized the actual body pose with red gizmos and the bodyPosition provided by the HumanPose with a green gizmo. You can see that the bodyPosition is drifiting away from the actual avatar position. Is this an intended behavior? Is there a fix for this issue regardless whether it is intended?

I tested it with the following versions:
2019.3.0f6
2019.3.6f1
2020.1.0b2 (as there seems some progress on human pose)

And I also tested it with four different characters. The degree of drift and the direction was varying for each.

Here is the code for my visualization script:

Code (CSharp):

1.     public class AvatarPoseVisualizer : MonoBehaviour
2.     {
3.  
4.         public Color32 poseColor;
5.         public float poseSphereRadius = 0.03f;
6.         public Color32 comColor;
7.         public float comSphereRadius = 0.05f;
8.  
9.         public Transform rootBone;
10.         private Animator animator;
11.         private HumanPoseHandler humanPoseHandler;
12.         private HumanPose humanPose;
13.  
14.         void OnEnable()
15.         {
16.             animator = GetComponent<Animator>();
17.             if (animator == null)
18.             {
19.                 Debug.LogError("No animator for visualization found, component was disabled.");
20.                 enabled = false;
21.             }
22.  
23.             humanPoseHandler = new HumanPoseHandler(animator.avatar, rootBone);
24.         }
25.  
26.         private void OnDrawGizmos()
27.         {
28.             if (animator != null)
29.             {
30.                 // Draw center of mass
31.                 Gizmos.color = comColor;
32.                 humanPoseHandler.GetHumanPose(ref humanPose);
33.                 Gizmos.DrawSphere(humanPose.bodyPosition, comSphereRadius);
34.                 Gizmos.color = poseColor;
35.  
36.                 // Draw skeleton
37.                 Gizmos.color = poseColor;
38.                 var avatarTransforms = new AvatarTransforms();
39.                 avatarTransforms.headTransform = animator.GetBoneTransform(HumanBodyBones.Head);
40.                 avatarTransforms.hipsTransform = animator.GetBoneTransform(HumanBodyBones.Hips);
41.                 avatarTransforms.leftShoulderTransform = animator.GetBoneTransform(HumanBodyBones.LeftShoulder);
42.                 avatarTransforms.rightShoulderTransform = animator.GetBoneTransform(HumanBodyBones.RightShoulder);
43.                 avatarTransforms.leftHandTransform = animator.GetBoneTransform(HumanBodyBones.LeftHand);
44.                 avatarTransforms.rightHandTransform = animator.GetBoneTransform(HumanBodyBones.RightHand);
45.                 avatarTransforms.leftElbowTransform = animator.GetBoneTransform(HumanBodyBones.LeftLowerArm);
46.                 avatarTransforms.rightElbowTransform = animator.GetBoneTransform(HumanBodyBones.RightLowerArm);
47.                 avatarTransforms.pelvisTransform = animator.GetBoneTransform(HumanBodyBones.Hips);
48.                 avatarTransforms.leftFootTransform = animator.GetBoneTransform(HumanBodyBones.LeftFoot);
49.                 avatarTransforms.rightFootTransform = animator.GetBoneTransform(HumanBodyBones.RightFoot);
50.                 avatarTransforms.leftKneeTransform = animator.GetBoneTransform(HumanBodyBones.LeftLowerLeg);
51.                 avatarTransforms.rightKneeTransform = animator.GetBoneTransform(HumanBodyBones.RightLowerLeg);
52.                 DrawAvatarSkeletonGizmo(avatarTransforms);
53.             }
54.         }
55.  
56.         private void DrawAvatarSkeletonGizmo(AvatarTransforms transforms)
57.         {
58.             Gizmos.DrawSphere(transforms.pelvisTransform.position, poseSphereRadius);
59.             Gizmos.DrawSphere(transforms.headTransform.position, poseSphereRadius);
60.             Gizmos.DrawLine(transforms.pelvisTransform.position, transforms.headTransform.position);
61.             Gizmos.DrawSphere(transforms.leftShoulderTransform.position, poseSphereRadius);
62.             Gizmos.DrawSphere(transforms.rightShoulderTransform.position, poseSphereRadius);
63.             Gizmos.DrawSphere(transforms.rightHandTransform.position, poseSphereRadius);
64.             Gizmos.DrawSphere(transforms.leftHandTransform.position, poseSphereRadius);
65.             Gizmos.DrawSphere(transforms.rightHandTransform.position, poseSphereRadius);
66.             Gizmos.DrawSphere(transforms.leftElbowTransform.position, poseSphereRadius);
67.             Gizmos.DrawSphere(transforms.rightElbowTransform.position, poseSphereRadius);
68.             Gizmos.DrawLine(transforms.pelvisTransform.position, transforms.leftShoulderTransform.position);
69.             Gizmos.DrawLine(transforms.pelvisTransform.position, transforms.rightShoulderTransform.position);
70.             Gizmos.DrawLine(transforms.leftShoulderTransform.position, transforms.leftElbowTransform.position);
71.             Gizmos.DrawLine(transforms.rightShoulderTransform.position, transforms.rightElbowTransform.position);
72.             Gizmos.DrawLine(transforms.leftElbowTransform.position, transforms.leftHandTransform.position);
73.             Gizmos.DrawLine(transforms.rightElbowTransform.position, transforms.rightHandTransform.position);
74.             Gizmos.DrawSphere(transforms.leftKneeTransform.position, poseSphereRadius);
75.             Gizmos.DrawSphere(transforms.rightKneeTransform.position, poseSphereRadius);
76.             Gizmos.DrawSphere(transforms.leftFootTransform.position, poseSphereRadius);
77.             Gizmos.DrawSphere(transforms.rightFootTransform.position, poseSphereRadius);
78.             Gizmos.DrawLine(transforms.pelvisTransform.position, transforms.leftKneeTransform.position);
79.             Gizmos.DrawLine(transforms.leftKneeTransform.position, transforms.leftFootTransform.position);
80.             Gizmos.DrawLine(transforms.pelvisTransform.position, transforms.rightKneeTransform.position);
81.             Gizmos.DrawLine(transforms.rightKneeTransform.position, transforms.rightFootTransform.position);
82.         }
83.     }

Thanks for your help in advance!!

 

Thats very interesting! Have you tried to scale the avatar? How does it behave then?

 

Scaling of the avatar does not affect the bodyPosition as it seems normalized.

 

https://issuetracker.unity3d.com/is...odel-is-moving-by-using-root-motion-animation

worldPosition = humanPose.bodyPosition * animator.humanScale;