for (ring = ao_gps_ring_next(gps_head); ring != gps_head; ring = ao_gps_ring_next(ring)) {
ground_distance = ao_distance(gps_data.latitude, gps_data.longitude,
gps_position[ring].latitude,
gps_position[ring].longitude);
for (ring = ao_gps_ring_next(gps_head); ring != gps_head; ring = ao_gps_ring_next(ring)) {
ground_distance = ao_distance(gps_data.latitude, gps_data.longitude,
gps_position[ring].latitude,
gps_position[ring].longitude);