Databases Reference
In-Depth Information
7
Motion Mediator
in section 5 we have introduced “mediator” to describe the shape of parts (ex.
human head) of objects in abstract and uniform way.
Now, we consider to extend this idea to structural description and motions.
Those are defined as follows.
•
Structure mediator
We can assume most of objects consist of several “solid” parts and “joints”
connecting parts each other. For example, a human body consists of head,
neck, shoulder, chest, right upper arm, left upper arm, and so on, and there
are specific joints between those parts with the specific DOF(Degree of
freedom). Structure Mediator is defined as joint values—range of motion
and other constraint between parts—for each person. Structure Mediator
can be regarded as an extension of shape (figure) mediator which can
describe not only “simple” “part” objects but “complex” object like human
body. This idea is shown in Figure. 15.
•
Motion Mediator
Motion Mediator is defined as a sequence of intermediate postures within
a motion which is done by a specific person. The intermediate posture
must be preliminary assigned to each typical motion.
For example,
Unit Walking:
I: Starting Motion
II: Motion
II-1 Right toe up
II-2 Right toe at ground
II-3 Left toe up
II-4 Left toe at ground
II-5 II-1
III: Ending Motion
are pre-assigned. (see Figure. 16)
The above intermediate postures can be detected by analyzing video images
easily. Similar to the shape mediator, Motion mediator can represent the
characteristics of a specific motion of a specific person, with a small amount
of data. Therefore, from a set of motion mediators, the database user can
calculate the average of the maximum height of right knee in a walking
motion. The authors group is now developing a formal description of generic
motion and a motion evaluation system in the framework of RWDB.
