-This is a very simple implementation of the KSP applied to
-multi-target tracking. It is dubbed Multi-Tracked Paths since it
-differs a bit from the standard KSP. It works with negative edge
-length and stops when it can not find any path of negative length,
-instead of fixing the total number of paths to a constant K.
+* INTRODUCTION
+
+This is a very simple implementation of a variant of KSP applied to
+multi-target tracking dubbed "Multi-Tracked Paths" (MTP).
+
+It works with negative edge length and stops when it can not find any
+path of negative total length, instead of fixing the total number of
+paths to a constant K.
+
+* INSTALLATION
+
+This source code should compile with any C++ compiler. Just run "make"
+and execute the mtp executable. It should print the optimal detected
+trajectories, and save into graph.dot the result graph and
+trajectories in the dot syntax. You can produce a pdf from the latter
+with
+
+ dot < graph.dot -T pdf -o graph.pdf
+
+* DESCRIPTION
The two main classes are MTPGraph and Tracker.
for(int l = 0; l < nb_locations; l++) {
for(int k = 0; k < nb_locations; k++) {
- tracker->set_allowed_motion(l, k, abs(l - k) <= motion_amplitude);
+ tracker->allowed_motion[l][k] = abs(l - k) <= motion_amplitude;
}
- tracker->set_as_entrance(0, 1);
- tracker->set_as_exit(nb_locations - 1, 1);
+ tracker->entrances[0] = 1;
+ tracker->exits[nb_locations - 1] = 1;
}
tracker->build_graph();
for(int t = 0; t < nb_time_steps; t++) {
for(int l = 0; l < nb_locations; l++) {
- tracker->set_detection_score(t, l, detection_score(-1, 0.95));
+ tracker->detection_score[t][l] = detection_score(-1, 0.95);
}
- tracker->set_detection_score(t, nb_locations/2, detection_score(1, 0.95));
+ tracker->detection_score[t][nb_locations/2] = detection_score(1, 0.95);
}
tracker->track();
_nb_locations = nb_locations;
_nb_time_steps = nb_time_steps;
- _detection_score = allocate_array<scalar_t>(_nb_time_steps, _nb_locations);
- _allowed_motion = allocate_array<int>(_nb_locations, _nb_locations);
+ detection_score = allocate_array<scalar_t>(_nb_time_steps, _nb_locations);
+ allowed_motion = allocate_array<int>(_nb_locations, _nb_locations);
- _entrances = new int[_nb_locations];
- _exits = new int[_nb_locations];
+ entrances = new int[_nb_locations];
+ exits = new int[_nb_locations];
for(int l = 0; l < nb_locations; l++) {
- _entrances[l] = 0;
- _exits[l] = 0;
+ entrances[l] = 0;
+ exits[l] = 0;
for(int m = 0; m < nb_locations; m++) {
- _allowed_motion[l][m] = 0;
+ allowed_motion[l][m] = 0;
}
}
for(int t = 0; t < _nb_time_steps; t++) {
for(int l = 0; l < _nb_locations; l++) {
- _detection_score[t][l] = 0.0;
+ detection_score[t][l] = 0.0;
}
}
Tracker::~Tracker() {
delete[] _edge_lengths;
delete _graph;
- deallocate_array<scalar_t>(_detection_score);
- deallocate_array<int>(_allowed_motion);
- delete[] _exits;
- delete[] _entrances;
-}
-
-void Tracker::set_allowed_motion(int from_location, int to_location, int v) {
- ASSERT(from_location >= 0 && from_location < _nb_locations &&
- to_location >= 0 && to_location < _nb_locations);
- _allowed_motion[from_location][to_location] = v;
-}
-
-void Tracker::set_as_entrance(int location, int v) {
- ASSERT(location >= 0 && location < _nb_locations);
- _entrances[location] = v;
-}
-
-void Tracker::set_as_exit(int location, int v) {
- ASSERT(location >= 0 && location < _nb_locations);
- _exits[location] = v;
-}
-
-void Tracker::set_detection_score(int time, int location, scalar_t score) {
- ASSERT(time >= 0 && time < _nb_time_steps &&
- location >= 0 && location < _nb_locations);
- _detection_score[time][location] = score;
+ deallocate_array<scalar_t>(detection_score);
+ deallocate_array<int>(allowed_motion);
+ delete[] exits;
+ delete[] entrances;
}
void Tracker::build_graph() {
int nb_motions = 0, nb_exits = 0, nb_entrances = 0;
for(int l = 0; l < _nb_locations; l++) {
- if(_exits[l]) nb_exits++;
- if(_entrances[l]) nb_entrances++;
+ if(exits[l]) nb_exits++;
+ if(entrances[l]) nb_entrances++;
for(int m = 0; m < _nb_locations; m++) {
- if(_allowed_motion[l][m]) nb_motions++;
+ if(allowed_motion[l][m]) nb_motions++;
}
}
// frame to the sink
_nb_locations * 2 +
// The edges from the source to the entrances and from the exists
- // to the sink (in every time frames but the first and last)
+ // to the sink (in every time frames but the first for the source,
+ // and last for the exits)
(_nb_time_steps - 1) * (nb_exits + nb_entrances) +
// The edges for the motions, between every pair of successive
// frames
_edge_lengths = new scalar_t[nb_edges];
// We put the in-node edges first, since these are the ones whose
- // lengths we will have to change according to the detection score
+ // lengths we will have to set later, according to the detection
+ // scores
for(int t = 0; t < _nb_time_steps; t++) {
for(int l = 0; l < _nb_locations; l++) {
e++;
} else {
for(int k = 0; k < _nb_locations; k++) {
- if(_allowed_motion[l][k]) {
+ if(allowed_motion[l][k]) {
node_from[e] = 1 + (2 * (t + 0) + 1) * _nb_locations + l;
node_to[e] = 1 + (2 * (t + 1) + 0) * _nb_locations + k;
_edge_lengths[e] = 0.0;
for(int t = 0; t < _nb_time_steps; t++) {
for(int l = 0; l < _nb_locations; l++) {
- if(t > 0 && _entrances[l]) {
+ if(t > 0 && entrances[l]) {
node_from[e] = source;
node_to[e] = 1 + (2 * (t + 0) + 0) * _nb_locations + l;
_edge_lengths[e] = 0.0;
e++;
}
- if(t < _nb_time_steps - 1 && _exits[l]) {
+ if(t < _nb_time_steps - 1 && exits[l]) {
node_from[e] = 1 + (2 * (t + 0) + 1) * _nb_locations + l;
node_to[e] = sink;
_edge_lengths[e] = 0.0;
int e = 0;
for(int t = 0; t < _nb_time_steps; t++) {
for(int l = 0; l < _nb_locations; l++) {
- _edge_lengths[e++] = - _detection_score[t][l];
+ _edge_lengths[e++] = - detection_score[t][l];
}
}
_graph->print_dot(os);
int e = 0;
for(int t = 0; t < _nb_time_steps; t++) {
for(int l = 0; l < _nb_locations; l++) {
- _edge_lengths[e++] = - _detection_score[t][l];
+ _edge_lengths[e++] = - detection_score[t][l];
}
}