| Volume 22 Issue 6 - Publication Date: 1 June 2003 |
| |
| Automatic Determination of Shoulder
Joint Limits Using Quaternion Field Boundaries |
| |
| L. Herda, R. Urtasun,
P. Fua,Computer Vision Laboratory, EPFL, CH-1015, Lausanne, Switzerland
and A. Hanson Computer Science Department, Indiana University,
Bloomington, IN 47405, USA |
| |
To provide efficient tools
for the capture and modeling of acceptable virtual human poses, we propose
a method for constraining the underlying joint structures based on real
life data. Current tools for delimiting valid postures often employ techniques
that do not represent joint limits in an intuitively satisfying manner,
and furthermore are seldom directly derived from experimental data. Here,
we propose a semi-automatic scheme for determining ball-and-socket joint
limits by actual measurement and we apply it to modeling the shoulder complex,
which---along with the hip complex---can be approximated by a three-degree-of-freedom
ball-and-socket joint. Our first step is to measure the joint motion range
using optical motion capture. We next convert the recorded values to joint
poses encoded using a coherent quaternion field representation of the joint
orientation space. Finally, we obtain a closed, continuous implicit surface
approximation for the quaternion orientation-space boundary whose interior
represents the complete space of valid orientations, enabling us to project
invalid postures to the closest valid ones.
|
| |
| Multimedia Key |
= Video |
 = Data |
= Code |
= Image |
|
| |
|
Extension |
Type |
Description |
1 |
|
Example
One: Manually specified motion without constraints seen from the
front. (0.2 MB) |
2 |
|
Example
Two: Manually specified motion without constraints seen from the
side. (1.1 MB) |
3 |
|
Example
Three: Same motion after joint limits have been enforced seen
from the front. (0.2 MB) |
4 |
|
Example
Four: Same motion after joint limits have been enforced seen from
the side. (1.0 MB) |
5 |
|
Example
Five: Manually specified motion without constraints seen from
the front. (1.6 MB) |
6 |
|
Example
Six: Manually specified motion without constraints seen from the
side. (1.0 MB) |
7 |
|
Example
Seven: Same motion after joint limits have been enforced seen
from the front. (2.2 MB) |
8 |
|
Example
Eight: Same motion after joint limits have been enforced seen
from the side. (1.3 MB) |
9 |
|
Example
Nine: Insufficient flexion constraint in the back region seen
from the front. (1.3 MB) |
10 |
|
Example
Ten: Insufficient flexion constraint in the back region seen from
the back. (0.8 MB) |
|
| |
| Return
to Contents |
