Adding comments.

[mtp.git] / mtp.cc

diff --git a/mtp.cc b/mtp.cc
index 59e950a..7f55e0a 100644 (file)
--- a/mtp.cc
+++ b/mtp.cc
@@ -18,13 +18,8 @@
 
 // Multi-Tracked Path
 
-// Takes the graph description file as input and produces a dot file.
-
-// EXAMPLE: ./mtp ./graph2.txt  | dot -T pdf -o- | xpdf -
-
 #include <iostream>
 #include <fstream>
-#include <stdlib.h>
 
 using namespace std;
 
@@ -32,55 +27,112 @@ using namespace std;
 
 //////////////////////////////////////////////////////////////////////
 
-scalar_t detection_score(int true_label) {
-  if((true_label > 0) == (drand48() < 0.9)) {
-    return   1.0 + 0.2 * (drand48() - 0.5);
+scalar_t detection_score(scalar_t a, scalar_t b, scalar_t score_noise, scalar_t flip_noise) {
+  if(drand48() > flip_noise) {
+    return a + score_noise * (2.0 * drand48() - 1.0);
   } else {
-    return - 1.0 + 0.2 * (drand48() - 0.5);
+    return b + score_noise * (2.0 * drand48() - 1.0);
   }
 }
 
 int main(int argc, char **argv) {
-  int nb_locations = 5;
-  int nb_time_steps = 20;
+  int nb_locations = 7;
+  int nb_time_steps = 8;
   int motion_amplitude = 1;
 
   Tracker *tracker = new Tracker(nb_time_steps, nb_locations);
 
+  // We define the spatial structures by stating what are the possible
+  // motions of targets, and what are the entrances and the
+  // exits.
+
+  // Here our example is a 1D space with motions from any location to
+  // any location less than motion_amplitude away, entrance at
+  // location 0 and exit at location nb_locations-1.
+
   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_exit(0, 1);
-    tracker->set_as_entrance(0, 1);
+    tracker->entrances[0] = 1;
+    tracker->exits[nb_locations - 1] = 1;
   }
 
+  // We construct the graph corresponding to this structure
+
   tracker->build_graph();
 
-  for(int r = 0; r < 10; r++) {
-    cout << "* ROUND " << r << endl;
+  // Then, we specify for every location and time step what is the
+  // detection score there.
 
-    // We generate synthetic detection scores, all in the center
-    // location, with 10% false detection (FP or FN)
+  scalar_t flip_noise = 0.05;
+  scalar_t score_noise = 0.0;
+
+  // We first put a background noise, with negative scores at every
+  // location.
+
+  for(int t = 0; t < nb_time_steps; t++) {
+    for(int l = 0; l < nb_locations; l++) {
+      tracker->detection_scores[t][l] = detection_score(-1.0, 1.0, score_noise, flip_noise);
+    }
+  }
 
-    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));
-      }
-      tracker->set_detection_score(t, nb_locations/2, detection_score(1));
+  // Then we two targets with the typical local minimum:
+  //
+  // * Target A moves from location 0 to the middle, stays there for a
+  //   while, and comes back, and is strongly detected on the first
+  //   half
+  //
+  // * Target B moves from location nb_locations-1 to the middle, stay
+  //   there for a while, and comes back, and is strongly detected on
+  //   the second half
+
+  int la, lb; // Target locations
+  scalar_t sa, sb; // Target detection scores
+  for(int t = 0; t < nb_time_steps; t++) {
+    if(t < nb_time_steps/2) {
+      la = t;
+      lb = nb_locations - 1 - t;
+      sa = detection_score(10.0, -1.0, score_noise, flip_noise);
+      sb = detection_score( 1.0, -1.0, score_noise, flip_noise);
+    } else {
+      la = nb_time_steps - 1 - t;
+      lb = t - nb_time_steps + nb_locations;
+      sa = detection_score( 1.0, -1.0, score_noise, flip_noise);
+      sb = detection_score(10.0, -1.0, score_noise, flip_noise);
     }
 
-    tracker->track();
+    if(la > nb_locations/2 - 1) la = nb_locations/2 - 1;
+    if(lb < nb_locations/2 + 1) lb = nb_locations/2 + 1;
 
-    for(int t = 0; t < tracker->nb_trajectories(); t++) {
-      cout << "TRAJECTORY "
-           << t
-           << " [starting " << tracker->trajectory_entrance_time(t) << "]";
-      for(int u = 0; u < tracker->trajectory_duration(t); u++) {
-        cout << " " << tracker->trajectory_location(t, u);
-      }
-      cout << endl;
+    tracker->detection_scores[t][la] = sa;
+    tracker->detection_scores[t][lb] = sb;
+  }
+
+  // Does the tracking per se
+
+  tracker->track();
+
+  // Prints the detected trajectories
+
+  for(int t = 0; t < tracker->nb_trajectories(); t++) {
+    cout << "TRAJECTORY "
+         << t
+         << " [starting " << tracker->trajectory_entrance_time(t)
+         << ", score " << tracker->trajectory_score(t) << "]";
+    for(int u = 0; u < tracker->trajectory_duration(t); u++) {
+      cout << " " << tracker->trajectory_location(t, u);
     }
+    cout << endl;
+  }
+
+  // Save the underlying graph in the dot format, with occupied edges
+  // marked in bold.
+
+  {
+    ofstream dot("graph.dot");
+    tracker->print_graph_dot(&dot);
+    cout << "Wrote graph.dot." << endl;
   }
 
   delete tracker;