Prof. B. Seth and his students of Department of Mechanical Engineering have
developed a method for tracking planar
movement of multiple objects from sequence of digital images using
markers. This invention is useful for videographic study of motion in
machines. Tracking of objects from a sequence of images requires automatic
identification of the objects of interest and accurate location and
orientation information of the tracked objects in each frame. The
approaches used to accomplish this include recognition based on the
radiation characteristics and reflective properties of the object itself
a tag or marker attached to the object. Use of markers, when permissible,
assist in tracking by facilitating automatic recognition of the objects.
Traditionally symmetric markers are used.
There are several drawbacks in the traditional marker system. In multiple
marker system there is the problem of marker correspondence (i.e.,
identifying the corresponding markers in successive image frames). This
problem can become unmanageable when markers get occluded or go out
of the field of view. Also a traditional marker yields accurate position
information; however, for obtaining accurate orientation
multiple markers are needed on the same body.
In this tracking system, a number of parts move in parallel planes and it
may be desirable to accurately track the motion
of some parts. Markers are afixed on the different bodies of interest. During
motion the markers can get occluded.
Advantages of the system
- Marker detection is robust
- There is no added difficulty when more markers are used
- A single mark yields both position and orientation information
- Correspondence problem of a marker is eliminated by a unique tag
- Re-tracking of an occluded markers starts immediately after the marker
comes in the camera view again
Indian patent application no. 1278/MUM/2003 Patent grant no. 206126
Inventors: B Seth, A C Acharya, R Raj, K Moharir