KSP: Multiple Object Tracker Using K-Shortest Paths
This code implements a multiple object tracker based on the
k-shortest paths algorithm. Its input consists in a set of
probabilistic occupancy maps, that is, for every time frame, a set
of occupancy probabilities, one for each of the potential target
locations. Such input data is usually produced by an object
detector.
The KSP object tracking algorithm is able to track an unknown and
varying number of objects. Unlike other related methods, it operates
on the full set of potential target locations, and not just on the
detections themselves. This characteristic allows it to handle
missing detections and false positives well.
Installation and test
The program should compile on any modern GNU/Linux system. Its only
external library requirement is the Boost library, which needs to be
installed along with its headers. To compile the program, simply
use the make command.
To run a simple test on occupancy maps provided in the archive just type
./ksp test.ksp
It will generate a result file ksp-out.dat in the current directory. An alternate output file name can be specified with the option -o.
Configuration file
The program relies on a configuration file that contains all the
parameters needed for applying the tracker. Below is a description
of the syntax of this file. Note that the lines starting with a
character # are considered as comments and ignored.
GRID <grid_width> <grid_height>
The program assumes that the potential target locations are
distributed as a regular grid. This command specifies the
dimensions of this grid.
FRAMES <first_frame> <last_frame>
This command specifies the time window of the sequence to process.
ACCESS_POINTS <pos1,pos2,pos3,...>
This command specifies which - if any - cells of the grid can act
as entrance and exit point, so that the number of objects can
vary. In an indoor people tracking application, those would
typically be locations close to doors, from which people can enter
or exit. The set is given as a comma separated list of cells. A
cell position is numbered by its coordinates in the grid:
position = x + y * grid_width
where the coordinates are defined in
[0, grid_width[ x [0, grid_height[ .
If there are no access point in the scene, this command should be
commented out.
DEPTH <depth>
The depth represents the maximum allowed movement in the grid
between two consecutive time frames. It is measured in grid
cells. A value of 1 means that you can reach the next grid cell at
most, while 2 means that you can travel 2 grid cells in any
direction.
MAX_TRAJ <maximum_number_of_trajectories>
This value represents an upper bound on the number of trajectories
retrieved by the algorithm. For implementation reasons, it cannot
be larger than 255.
INPUT_FORMAT <input_file_format>
This string specifies the file format of the input data. Each time
frame is stored in a different file, and every file contains, at
each line, the number of the grid cell and its probability of
occupancy. Thus the input file format should contain a special
character %d that will be replaced by the frame number, in the
standard printf way.
An example configuration file named test.ksp is provided for
convenience. It performs tracking on the probabilistic occupancy
maps stored in the folder proba. Note that this data has been
generated with the POM people detector available at
http://cvlab.epfl.ch/software/pom .
For more information about the KSP algorithm, please check the
following article:
License
The source code is available upon request for academic purposes only
and is distributed under a proprietary non-commercial
license. If you are interested in using this algorithm in a
commercial product, you can contact us to purchase a commercial
license.
Contact
Please mail pom@epfl.ch for bug reports, comments and questions.
Source code
The code is available upon request. Please contact pom@epfl.ch to obtain a copy of the
source code.
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Last update :
18 April 2012 09:08:45
