Proj.Geodesic (proj v0.2.3)
Provides functions to solve problems involving geodesic lines.
Common problems this can solve:
Finding the distance between two locations
Finding the bearings between two locations
Finding the resulting location after moving
xmetres forwards facing a certain bearing from a given locationPlotting a set of points in a line between two locations
Link to this section Summary
Functions
Calculates the resultant coordinates and bearing after travelling a given distance forwards along a geodesic line through a given starting point and azimuth (bearing).
Calculates the distance in metres between two points.
Creates a new Proj.Geodesic specification for the planet's ellipsoid
parameters, where a represents the equatorial radius in metres, and f
represents the flattening.
Calculates the length of the geodesic line between two points and the bearing of the line at each point.
Gets the equatorial radius in metres and flattening of a given Proj.Geodesic
ellipsoid specification.
Calculates the resulting position after travelling distance metres forwards
from coords facing a bearing of azimuth.
Returns a Proj.Geodesic specification for the Earth's ellipsoid parameters
as specified by WGS84.
Link to this section Functions
direct(geod, coords, azimuth, distance)
Calculates the resultant coordinates and bearing after travelling a given distance forwards along a geodesic line through a given starting point and azimuth (bearing).
Return value is in the format {{lat, lng}, bearing}.
All coordinates and bearings are given in degrees. distance is in metres.
iex> wgs84 = Proj.Geodesic.wgs84
iex> Proj.Geodesic.direct(wgs84, {51.501476, -0.140634}, 60, 100)
{{51.50192539979596, -0.1393868003258145}, 60.00097609168357}distance(coords_a, coords_b)
Calculates the distance in metres between two points.
This is a convenience wrapper around Proj.Geodesic.inverse/3 which uses the
WGS84 ellipsoid and only returns the resulting distance.
All coordinates are given in degrees.
iex> Proj.Geodesic.distance({51.501476, -0.140634}, {48.8584, 2.2945})
341549.6819692767init(a, f)
Creates a new Proj.Geodesic specification for the planet's ellipsoid
parameters, where a represents the equatorial radius in metres, and f
represents the flattening.
iex> Proj.Geodesic.init(6378137, 1 / 298.257223563)
#Proj.Geodesic<6378137.0, 0.0033528106647474805>inverse(geod, coords_a, coords_b)
Calculates the length of the geodesic line between two points and the bearing of the line at each point.
Return value is in the format {distance, bearing_a, bearing_b}.
All coordinates and bearings are given in degrees. distance is in metres.
iex> wgs84 = Proj.Geodesic.wgs84
iex> Proj.Geodesic.inverse(wgs84, {51.501476, -0.140634}, {48.8584, 2.2945})
{341549.6819692767, 148.44884919324866, 150.31979086555856}load()
params(geod)
Gets the equatorial radius in metres and flattening of a given Proj.Geodesic
ellipsoid specification.
Return value is in the format {equatorial_radius, flattening}
iex> wgs84 = Proj.Geodesic.wgs84
iex> Proj.Geodesic.params(wgs84)
{6378137.0, 0.0033528106647474805}travel(coords, azimuth, distance)
Calculates the resulting position after travelling distance metres forwards
from coords facing a bearing of azimuth.
This is a convenience wrapper around Proj.Geodesic.direct/4 which uses the
WGS84 ellipsoid and only returns the resulting coordinates.
Return value is in the format {lat, lng}.
All coordinates and bearings are given in degrees.
iex> Proj.Geodesic.travel({51.501476, -0.140634}, 60, 100)
{51.50192539979596, -0.1393868003258145}wgs84()
Returns a Proj.Geodesic specification for the Earth's ellipsoid parameters
as specified by WGS84.