/*
- * 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>
#include "mtp_graph.h"
-#include <iostream>
#include <float.h>
-#include <stdlib.h>
using namespace std;
scalar_t distance_from_source;
Edge *pred_edge_toward_source;
- int iteration; // Used in find_shortest_path to know if we already
- // added this vertex to the front
+ int last_change; // Used to mark which edges have already been
+ // processed in some methods
+
Vertex();
+
inline void add_leaving_edge(Edge *e);
inline void del_leaving_edge(Edge *e);
};
void Edge::invert() {
length = - length;
- positivized_length = 0;
+ positivized_length = - positivized_length;
origin_vertex->del_leaving_edge(this);
terminal_vertex->add_leaving_edge(this);
Vertex *t = terminal_vertex;
_source = &_vertices[source];
_sink = &_vertices[sink];
- for(int v = 0; v < _nb_vertices; v++) {
- _vertices[v].id = v;
+ for(int k = 0; k < _nb_vertices; k++) {
+ _vertices[k].id = k;
}
for(int e = 0; e < nb_edges; e++) {
void MTPGraph::print_dot(ostream *os) {
(*os) << "digraph {" << endl;
+ (*os) << " rankdir=\"LR\";" << endl;
(*os) << " node [shape=circle,width=0.75,fixedsize=true];" << endl;
(*os) << " edge [color=gray,arrowhead=open]" << endl;
(*os) << " " << _source->id << " [peripheries=2];" << endl;
(*os) << " " << _sink->id << " [peripheries=2];" << endl;
- // (*os) << " " << _source->id << " [style=bold,color=red];" << endl;
- // (*os) << " " << _sink->id << " [style=bold,color=green];" << endl;
for(int k = 0; k < _nb_edges; k++) {
Edge *e = _edges + k;
- // (*os) << " " << e->origin_vertex->id << " -> " << e->terminal_vertex->id
- // << ";"
- // << endl;
(*os) << " " << e->origin_vertex->id << " -> " << e->terminal_vertex->id
<< " [";
if(e->occupied) {
scalar_t residual_error = 0.0;
scalar_t max_error = 0.0;
#endif
- for(int n = 0; n < _nb_vertices; n++) {
- for(Edge *e = _vertices[n].leaving_edges; e; e = e->next_leaving_edge) {
- if(e->positivized_length < 0) {
+ for(int k = 0; k < _nb_edges; k++) {
+ Edge *e = _edges + k;
+
+ if(e->positivized_length < 0) {
+
#ifdef VERBOSE
+ if((e->origin_vertex->last_change < 0 && e->terminal_vertex->last_change >= 0) ||
+ (e->origin_vertex->last_change >= 0 && e->terminal_vertex->last_change < 0)) {
+ cout << "Inconsistent non-connexity (this should never happen)." << endl;
+ abort();
+ }
+ if(e->origin_vertex->last_change >= 0 &&
+ e->terminal_vertex->last_change >= 0 &&
+ e->positivized_length < 0) {
residual_error -= e->positivized_length;
max_error = max(max_error, - e->positivized_length);
-#endif
- e->positivized_length = 0.0;
}
+#endif
+ e->positivized_length = 0.0;
}
}
#ifdef VERBOSE
#endif
}
-// This method does not change the edge occupation. It update
-// distance_from_source and pred_edge_toward_source.
+int MTPGraph::is_dag() {
+ Vertex *v;
+ Edge *e;
+
+ // We put everybody in the front
+ for(int k = 0; k < _nb_vertices; k++) {
+ _vertices[k].last_change = -1;
+ _front[k] = &_vertices[k];
+ }
+
+ int iteration = 0;
+ int front_size = _nb_vertices, pred_front_size;
+
+ do {
+ // We set the last_change field of all the vertices with incoming
+ // edges to the current iteration value
+ for(int f = 0; f < front_size; f++) {
+ v = _front[f];
+ for(e = v->leaving_edges; e; e = e->next_leaving_edge) {
+ e->terminal_vertex->last_change = iteration;
+ }
+ }
+
+ pred_front_size = front_size;
+ front_size = 0;
+
+ // We keep all the vertices with incoming nodes
+ for(int f = 0; f < pred_front_size; f++) {
+ v = _front[f];
+ if(v->last_change == iteration) {
+ _front[front_size++] = v;
+ }
+ }
+
+ iteration++;
+ } while(front_size < pred_front_size);
+
+ return front_size == 0;
+}
+
+// This method does not change the edge occupation. It only set
+// properly, for every vertex, the fields distance_from_source and
+// pred_edge_toward_source.
+
void MTPGraph::find_shortest_path() {
Vertex **tmp_front;
- int tmp_front_size;
Vertex *v, *tv;
Edge *e;
scalar_t d;
- for(int v = 0; v < _nb_vertices; v++) {
- _vertices[v].distance_from_source = FLT_MAX;
- _vertices[v].pred_edge_toward_source = 0;
- _vertices[v].iteration = 0;
+#ifdef DEBUG
+ if(is_dag()) {
+ cout << "find_shortest_path: DAG -> ok" << endl;
+ } else {
+ for(int e = 0; e < _nb_edges; e++) {
+ if(_edges[e].positivized_length < 0) abort();
+ }
+ cout << "find_shortest_path: All positivized_length are positive -> ok" << endl;
+ }
+#endif
+
+ for(int k = 0; k < _nb_vertices; k++) {
+ _vertices[k].distance_from_source = FLT_MAX;
+ _vertices[k].pred_edge_toward_source = 0;
+ _vertices[k].last_change = -1;
}
int iteration = 0;
- int _front_size = 0, _new_front_size;
- _front[_front_size++] = _source;
+ int front_size = 0, new_front_size;
+ _front[front_size++] = _source;
_source->distance_from_source = 0;
do {
- _new_front_size = 0;
- iteration++;
+ new_front_size = 0;
- for(int f = 0; f < _front_size; f++) {
+ for(int f = 0; f < front_size; f++) {
v = _front[f];
for(e = v->leaving_edges; e; e = e->next_leaving_edge) {
d = v->distance_from_source + e->positivized_length;
if(d < tv->distance_from_source) {
tv->distance_from_source = d;
tv->pred_edge_toward_source = e;
- if(tv->iteration < iteration) {
- _new_front[_new_front_size++] = tv;
- tv->iteration = iteration;
+ if(tv->last_change < iteration) {
+ _new_front[new_front_size++] = tv;
+ tv->last_change = iteration;
}
}
}
}
- tmp_front = _new_front;
- _new_front = _front;
- _front = tmp_front;
+ tmp_front = _new_front; _new_front = _front; _front = tmp_front;
- tmp_front_size = _new_front_size;
- _new_front_size = _front_size;
- _front_size = tmp_front_size;
- } while(_front_size > 0);
+ front_size = new_front_size;
+
+ iteration++;
+ } while(front_size > 0);
}
void MTPGraph::find_best_paths(scalar_t *lengths) {
_edges[e].positivized_length = _edges[e].length;
}
- // We use one iteration of find_shortest_path simply to propagate
- // the distance to make all the edge lengths positive.
+ // We call find_shortest_path here to set properly the distances to
+ // the source, so that we can make all the edge lengths positive at
+ // the first iteration.
find_shortest_path();
do {
total_length = 0.0;
- // Do we reach the _sink?
+ // Do we reach the sink?
if(_sink->pred_edge_toward_source) {
- // If yes, compute the length of the best path
+ // If yes, compute the length of the best path according to the
+ // original edge lengths
v = _sink;
while(v->pred_edge_toward_source) {
total_length += v->pred_edge_toward_source->length;
// Put back the graph in its original state (i.e. invert edges which
// have been inverted in the process)
for(int k = 0; k < _nb_edges; k++) {
- Edge *e = _edges + k;
+ e = _edges + k;
if(e->occupied) { e->invert(); }
}
}
int nb_choices = 0;
for(f = e->terminal_vertex->leaving_edges; f; f = f->next_leaving_edge) {
if(f->occupied) { nb_choices++; next = f; }
- if(nb_choices == 0) {
- cerr << "retrieve_one_path: Non-sink end point." << endl;
- abort();
- }
- if(nb_choices > 1) {
- cerr << "retrieve_one_path: Non node-disjoint paths." << endl;
- abort();
- }
}
+
+#ifdef DEBUG
+ if(nb_choices == 0) {
+ cerr << "retrieve_one_path: Non-sink end point." << endl;
+ abort();
+ }
+ if(nb_choices > 1) {
+ cerr << "retrieve_one_path: Non node-disjoint paths." << endl;
+ abort();
+ }
+#endif
+
e = next;
}
projects / mtp.git / blobdiff