+/**
+ * Make a distance/time map, heavily based on the vik_track_make_speed_map method
+ */
+gdouble *vik_track_make_distance_map ( const VikTrack *tr, guint16 num_chunks )
+{
+ gdouble *v, *s, *t;
+ gdouble duration, chunk_dur;
+ time_t t1, t2;
+ int i, pt_count, numpts, index;
+ GList *iter;
+
+ if ( ! tr->trackpoints )
+ return NULL;
+
+ t1 = VIK_TRACKPOINT(tr->trackpoints->data)->timestamp;
+ t2 = VIK_TRACKPOINT(g_list_last(tr->trackpoints)->data)->timestamp;
+ duration = t2 - t1;
+
+ if ( !t1 || !t2 || !duration )
+ return NULL;
+
+ if (duration < 0) {
+ g_warning("negative duration: unsorted trackpoint timestamps?");
+ return NULL;
+ }
+ pt_count = vik_track_get_tp_count(tr);
+
+ v = g_malloc ( sizeof(gdouble) * num_chunks );
+ chunk_dur = duration / num_chunks;
+
+ s = g_malloc(sizeof(double) * pt_count);
+ t = g_malloc(sizeof(double) * pt_count);
+
+ iter = tr->trackpoints->next;
+ numpts = 0;
+ s[0] = 0;
+ t[0] = VIK_TRACKPOINT(iter->prev->data)->timestamp;
+ numpts++;
+ while (iter) {
+ s[numpts] = s[numpts-1] + vik_coord_diff ( &(VIK_TRACKPOINT(iter->prev->data)->coord), &(VIK_TRACKPOINT(iter->data)->coord) );
+ t[numpts] = VIK_TRACKPOINT(iter->data)->timestamp;
+ numpts++;
+ iter = iter->next;
+ }
+
+ /* In the following computation, we iterate through periods of time of duration chunk_dur.
+ * The first period begins at the beginning of the track. The last period ends at the end of the track.
+ */
+ index = 0; /* index of the current trackpoint. */
+ for (i = 0; i < num_chunks; i++) {
+ /* we are now covering the interval from t[0] + i*chunk_dur to t[0] + (i+1)*chunk_dur.
+ * find the first trackpoint outside the current interval, averaging the distance between intermediate trackpoints.
+ */
+ if (t[0] + i*chunk_dur >= t[index]) {
+ gdouble acc_s = 0; // No need for acc_t
+ while (t[0] + i*chunk_dur >= t[index]) {
+ acc_s += (s[index+1]-s[index]);
+ index++;
+ }
+ // The only bit that's really different from the speed map - just keep an accululative record distance
+ v[i] = i ? v[i-1]+acc_s : acc_s;
+ }
+ else if (i) {
+ v[i] = v[i-1];
+ }
+ else {
+ v[i] = 0;
+ }
+ }
+ g_free(s);
+ g_free(t);
+ return v;
+}
+
+/**
+ * This uses the 'time' based method to make the graph, (which is a simpler compared to the elevation/distance)
+ * This results in a slightly blocky graph when it does not have many trackpoints: <60
+ * NB Somehow the elevation/distance applies some kind of smoothing algorithm,
+ * but I don't think any one understands it any more (I certainly don't ATM)
+ */
+gdouble *vik_track_make_elevation_time_map ( const VikTrack *tr, guint16 num_chunks )
+{
+ time_t t1, t2;
+ gdouble duration, chunk_dur;
+ GList *iter = tr->trackpoints;
+
+ if (!iter || !iter->next) /* zero- or one-point track */
+ return NULL;
+
+ /* test if there's anything worth calculating */
+ gboolean okay = FALSE;
+ while ( iter ) {
+ if ( VIK_TRACKPOINT(iter->data)->altitude != VIK_DEFAULT_ALTITUDE ) {
+ okay = TRUE;
+ break;
+ }
+ iter = iter->next;
+ }
+ if ( ! okay )
+ return NULL;
+
+ t1 = VIK_TRACKPOINT(tr->trackpoints->data)->timestamp;
+ t2 = VIK_TRACKPOINT(g_list_last(tr->trackpoints)->data)->timestamp;
+ duration = t2 - t1;
+
+ if ( !t1 || !t2 || !duration )
+ return NULL;
+
+ if (duration < 0) {
+ g_warning("negative duration: unsorted trackpoint timestamps?");
+ return NULL;
+ }
+ gint pt_count = vik_track_get_tp_count(tr);
+
+ // Reset iterator back to the beginning
+ iter = tr->trackpoints;
+
+ gdouble *pts = g_malloc ( sizeof(gdouble) * num_chunks ); // The return altitude values
+ gdouble *s = g_malloc(sizeof(double) * pt_count); // calculation altitudes
+ gdouble *t = g_malloc(sizeof(double) * pt_count); // calculation times
+
+ chunk_dur = duration / num_chunks;
+
+ s[0] = VIK_TRACKPOINT(iter->data)->altitude;
+ t[0] = VIK_TRACKPOINT(iter->data)->timestamp;
+ iter = tr->trackpoints->next;
+ gint numpts = 1;
+ while (iter) {
+ s[numpts] = VIK_TRACKPOINT(iter->data)->altitude;
+ t[numpts] = VIK_TRACKPOINT(iter->data)->timestamp;
+ numpts++;
+ iter = iter->next;
+ }
+
+ /* In the following computation, we iterate through periods of time of duration chunk_dur.
+ * The first period begins at the beginning of the track. The last period ends at the end of the track.
+ */
+ gint index = 0; /* index of the current trackpoint. */
+ gint i;
+ for (i = 0; i < num_chunks; i++) {
+ /* we are now covering the interval from t[0] + i*chunk_dur to t[0] + (i+1)*chunk_dur.
+ * find the first trackpoint outside the current interval, averaging the heights between intermediate trackpoints.
+ */
+ if (t[0] + i*chunk_dur >= t[index]) {
+ gdouble acc_s = s[index]; // initialise to first point
+ while (t[0] + i*chunk_dur >= t[index]) {
+ acc_s += (s[index+1]-s[index]);
+ index++;
+ }
+ pts[i] = acc_s;
+ }
+ else if (i) {
+ pts[i] = pts[i-1];
+ }
+ else {
+ pts[i] = 0;
+ }
+ }
+ g_free(s);
+ g_free(t);
+
+ return pts;
+}
+
+/**
+ * Make a speed/distance map
+ */
+gdouble *vik_track_make_speed_dist_map ( const VikTrack *tr, guint16 num_chunks )
+{
+ gdouble *v, *s, *t;
+ time_t t1, t2;
+ gint i, pt_count, numpts, index;
+ GList *iter;
+ gdouble duration, total_length, chunk_length;
+
+ if ( ! tr->trackpoints )
+ return NULL;
+
+ t1 = VIK_TRACKPOINT(tr->trackpoints->data)->timestamp;
+ t2 = VIK_TRACKPOINT(g_list_last(tr->trackpoints)->data)->timestamp;
+ duration = t2 - t1;
+
+ if ( !t1 || !t2 || !duration )
+ return NULL;
+
+ if (duration < 0) {
+ g_warning("negative duration: unsorted trackpoint timestamps?");
+ return NULL;
+ }
+
+ total_length = vik_track_get_length_including_gaps ( tr );
+ chunk_length = total_length / num_chunks;
+ pt_count = vik_track_get_tp_count(tr);
+
+ if (chunk_length <= 0) {
+ return NULL;
+ }
+
+ v = g_malloc ( sizeof(gdouble) * num_chunks );
+ s = g_malloc ( sizeof(double) * pt_count );
+ t = g_malloc ( sizeof(double) * pt_count );
+
+ // No special handling of segments ATM...
+ iter = tr->trackpoints->next;
+ numpts = 0;
+ s[0] = 0;
+ t[0] = VIK_TRACKPOINT(iter->prev->data)->timestamp;
+ numpts++;
+ while (iter) {
+ s[numpts] = s[numpts-1] + vik_coord_diff ( &(VIK_TRACKPOINT(iter->prev->data)->coord), &(VIK_TRACKPOINT(iter->data)->coord) );
+ t[numpts] = VIK_TRACKPOINT(iter->data)->timestamp;
+ numpts++;
+ iter = iter->next;
+ }
+
+ // Iterate through a portion of the track to get an average speed for that part
+ // This will essentially interpolate between segments, which I think is right given the usage of 'get_length_including_gaps'
+ index = 0; /* index of the current trackpoint. */
+ for (i = 0; i < num_chunks; i++) {
+ // Similar to the make_speed_map, but instead of using a time chunk, use a distance chunk
+ if (s[0] + i*chunk_length >= s[index]) {
+ gdouble acc_t = 0, acc_s = 0;
+ while (s[0] + i*chunk_length >= s[index]) {
+ acc_s += (s[index+1]-s[index]);
+ acc_t += (t[index+1]-t[index]);
+ index++;
+ }
+ v[i] = acc_s/acc_t;
+ }
+ else if (i) {
+ v[i] = v[i-1];
+ }
+ else {
+ v[i] = 0;
+ }
+ }
+ g_free(s);
+ g_free(t);
+ return v;
+}
+
projects / andy / viking.git / blobdiff