kopia lustrzana https://github.com/projecthorus/chasemapper
140 wiersze
4.4 KiB
Python
140 wiersze
4.4 KiB
Python
#!/usr/bin/env python
|
|
#
|
|
# Project Horus - Browser-Based Chase Mapper
|
|
# Listeners
|
|
#
|
|
# Copyright (C) 2018 Mark Jessop <vk5qi@rfhead.net>
|
|
# Released under GNU GPL v3 or later
|
|
#
|
|
|
|
from math import radians, degrees, sin, cos, atan2, sqrt, pi
|
|
|
|
|
|
def position_info(listener, balloon):
|
|
"""
|
|
Calculate and return information from 2 (lat, lon, alt) tuples
|
|
|
|
Copyright 2012 (C) Daniel Richman; GNU GPL 3
|
|
|
|
Returns a dict with:
|
|
|
|
- angle at centre
|
|
- great circle distance
|
|
- distance in a straight line
|
|
- bearing (azimuth or initial course)
|
|
- elevation (altitude)
|
|
|
|
Input and output latitudes, longitudes, angles, bearings and elevations are
|
|
in degrees, and input altitudes and output distances are in meters.
|
|
"""
|
|
|
|
# Earth:
|
|
# radius = 6371000.0
|
|
radius = 6364963.0 # Optimized for Australia :-)
|
|
|
|
(lat1, lon1, alt1) = listener
|
|
(lat2, lon2, alt2) = balloon
|
|
|
|
lat1 = radians(lat1)
|
|
lat2 = radians(lat2)
|
|
lon1 = radians(lon1)
|
|
lon2 = radians(lon2)
|
|
|
|
# Calculate the bearing, the angle at the centre, and the great circle
|
|
# distance using Vincenty's_formulae with f = 0 (a sphere). See
|
|
# http://en.wikipedia.org/wiki/Great_circle_distance#Formulas and
|
|
# http://en.wikipedia.org/wiki/Great-circle_navigation and
|
|
# http://en.wikipedia.org/wiki/Vincenty%27s_formulae
|
|
d_lon = lon2 - lon1
|
|
sa = cos(lat2) * sin(d_lon)
|
|
sb = (cos(lat1) * sin(lat2)) - (sin(lat1) * cos(lat2) * cos(d_lon))
|
|
bearing = atan2(sa, sb)
|
|
aa = sqrt((sa ** 2) + (sb ** 2))
|
|
ab = (sin(lat1) * sin(lat2)) + (cos(lat1) * cos(lat2) * cos(d_lon))
|
|
angle_at_centre = atan2(aa, ab)
|
|
great_circle_distance = angle_at_centre * radius
|
|
|
|
# Armed with the angle at the centre, calculating the remaining items
|
|
# is a simple 2D triangley circley problem:
|
|
|
|
# Use the triangle with sides (r + alt1), (r + alt2), distance in a
|
|
# straight line. The angle between (r + alt1) and (r + alt2) is the
|
|
# angle at the centre. The angle between distance in a straight line and
|
|
# (r + alt1) is the elevation plus pi/2.
|
|
|
|
# Use sum of angle in a triangle to express the third angle in terms
|
|
# of the other two. Use sine rule on sides (r + alt1) and (r + alt2),
|
|
# expand with compound angle formulae and solve for tan elevation by
|
|
# dividing both sides by cos elevation
|
|
ta = radius + alt1
|
|
tb = radius + alt2
|
|
ea = (cos(angle_at_centre) * tb) - ta
|
|
eb = sin(angle_at_centre) * tb
|
|
elevation = atan2(ea, eb)
|
|
|
|
# Use cosine rule to find unknown side.
|
|
distance = sqrt((ta ** 2) + (tb ** 2) - 2 * tb * ta * cos(angle_at_centre))
|
|
|
|
# Give a bearing in range 0 <= b < 2pi
|
|
if bearing < 0:
|
|
bearing += 2 * pi
|
|
|
|
return {
|
|
"listener": listener,
|
|
"balloon": balloon,
|
|
"listener_radians": (lat1, lon1, alt1),
|
|
"balloon_radians": (lat2, lon2, alt2),
|
|
"angle_at_centre": degrees(angle_at_centre),
|
|
"angle_at_centre_radians": angle_at_centre,
|
|
"bearing": degrees(bearing),
|
|
"bearing_radians": bearing,
|
|
"great_circle_distance": great_circle_distance,
|
|
"straight_distance": distance,
|
|
"elevation": degrees(elevation),
|
|
"elevation_radians": elevation,
|
|
}
|
|
|
|
|
|
def bearing_to_cardinal(bearing):
|
|
""" Convert a bearing in degrees to a 16-point cardinal direction """
|
|
bearing = bearing % 360.0
|
|
|
|
if bearing < 11.25:
|
|
cardinal = "N"
|
|
elif 11.25 <= bearing < 33.75:
|
|
cardinal = "NNE"
|
|
elif 33.75 <= bearing < 56.25:
|
|
cardinal = "NE"
|
|
elif 56.25 <= bearing < 78.75:
|
|
cardinal = "ENE"
|
|
elif 78.75 <= bearing < 101.25:
|
|
cardinal = "E"
|
|
elif 101.25 <= bearing < 123.75:
|
|
cardinal = "ESE"
|
|
elif 123.75 <= bearing < 146.25:
|
|
cardinal = "SE"
|
|
elif 146.25 <= bearing < 168.75:
|
|
cardinal = "SSE"
|
|
elif 168.75 <= bearing < 191.25:
|
|
cardinal = "S"
|
|
elif 191.25 <= bearing < 213.75:
|
|
cardinal = "SSW"
|
|
elif 213.75 <= bearing < 236.25:
|
|
cardinal = "SW"
|
|
elif 236.25 <= bearing < 258.75:
|
|
cardinal = "WSW"
|
|
elif 258.75 <= bearing < 281.25:
|
|
cardinal = "W"
|
|
elif 281.25 <= bearing < 303.75:
|
|
cardinal = "WNW"
|
|
elif 303.75 <= bearing < 326.25:
|
|
cardinal = "NW"
|
|
elif 326.25 <= bearing < 348.75:
|
|
cardinal = "NNW"
|
|
elif bearing >= 348.75:
|
|
cardinal = "N"
|
|
else:
|
|
cardinal = "?"
|
|
|
|
return cardinal
|