/*
- * mtp is the ``Multi Tracked Path'', an implementation of the
- * k-shortest path algorithm for multi-target tracking.
+ * mtp is the ``Multi Tracked Paths'', an implementation of the
+ * k-shortest paths algorithm for multi-target tracking.
*
* Copyright (c) 2012 Idiap Research Institute, http://www.idiap.ch/
* Written by Francois Fleuret <francois.fleuret@idiap.ch>
class Edge;
class MTPGraph {
+ // Uses the estimated vertex distances to the source to make all the
+ // edge lengths positive, resulting in an identical added value to
+ // all the paths from the same initial node to the same final node
+ // (in particular from source to sink)
void update_positivized_lengths();
+
+ // It may happen that numerical errors in update_positivized_lengths
+ // make the resulting lengths negative, albeit very small. The
+ // following method forces all negative lengths to zero, and prints
+ // the total correction when compiled in VERBOSE mode.
void force_positivized_lengths();
- // Set the edge pred_edge_toward_source correspondingly to the path
- // of shortest length.
+
+ void decrease_distance_in_heap(Vertex *v);
+ void increase_distance_in_heap(Vertex *v);
+
+ // Visit the vertices according to _dp_order and simply update their
+ // distance to the source
+ void dp_distance_propagation();
+
+ // Set in every vertex pred_edge_toward_source correspondingly to
+ // the path of shortest length. The current implementation is
+ // Dijkstra with a Binary Heap (and not with Fibonnaci heap (yet))
void find_shortest_path();
- // Follows the path starting on edge e and returns its length. If
- // nodes is non-null, stores in it the nodes met along the path.
+
+ // Follows the path starting on edge e and returns the number of
+ // nodes to reach the sink. If path is non-null, stores in it the
+ // nodes met along the path, and computes path->length properly.
int retrieve_one_path(Edge *e, Path *path);
- Vertex **_front, **_new_front;
+ // Returns if the graph is a DAG, and set the last_change field of
+ // each vertex to the maximum number of iterations required to reach
+ // it
+ int check_DAG_and_set_last_change();
int _nb_vertices, _nb_edges;
Vertex *_source, *_sink;
Edge *_edges;
Vertex *_vertices;
+ // For the shortest path search
+
+ Vertex **_heap;
+ int _heap_size;
+
+ Vertex **_dp_order;
+
public:
// These variables are filled when retrieve_disjoint_paths is called
int nb_paths;
Path **paths;
- MTPGraph(int nb_vertices, int nb_edges, int *from, int *to,
+ MTPGraph(int nb_vertices, int nb_edges, int *vertex_from, int *vertex_to,
int source, int sink);
~MTPGraph();
+ // Compute the family of path with minimum total length, set the
+ // edge occupied fields accordingly.
void find_best_paths(scalar_t *lengths);
+
+ // Retrieve the path corresponding to the occupied edges, and save
+ // the result in the nb_paths and paths fields.
void retrieve_disjoint_paths();
void print(ostream *os);