diff options
Diffstat (limited to 'gpsprof')
| -rwxr-xr-x | gpsprof | 22 |
1 files changed, 19 insertions, 3 deletions
@@ -20,6 +20,22 @@ import socket import sys import time +def EarthDistanceSmall(c1, c2): + "Distance in meters between two close points specified in degrees." + # This calculation is known as an Equirectangular Projection + # fewer numeric issues for small angles that other methods + (lat1, lon1) = c1 + (lat2, lon2) = c2 + dlat = lat1 - lat2 + avglat = (lat1 + lat2 ) /2 + dlon = (lon1 - lon2) * math.cos( math.radians( avglat ) ) + # Earth Mean Radius 6371000 meters. + # one degree lat, average 111.133000 + # at equator 110.567 km + # at poll 111.699 km + dist = math.sqrt( dlat * dlat + dlon * dlon) * 111133 + return dist; + class Baton(object): "Ship progress indication to stderr." @@ -201,9 +217,9 @@ class spaceplot(plotter): def plot(self): # Compute CEP(50%) - cep_meters = gps.EarthDistance(self.centroid[:2], self.fixes[int(len(self.fixes) * 0.50)][:2]) - cep95_meters = gps.EarthDistance(self.centroid[:2], self.fixes[int(len(self.fixes) * 0.95)][:2]) - cep99_meters = gps.EarthDistance(self.centroid[:2], self.fixes[int(len(self.fixes) * 0.99)][:2]) + cep_meters = EarthDistanceSmall(self.centroid[:2], self.fixes[int(len(self.fixes) * 0.50)][:2]) + cep95_meters = EarthDistanceSmall(self.centroid[:2], self.fixes[int(len(self.fixes) * 0.95)][:2]) + cep99_meters = EarthDistanceSmall(self.centroid[:2], self.fixes[int(len(self.fixes) * 0.99)][:2]) alt_sum = 0 alt_num = 0 alt_fixes = [] |