Python tools for working with common victorian ( nsw) map projections
poetry install
Points on ellipsoidal surfaces are represented by GeoPoint instances and points in the 2d x-y plane are represented by the PlanePoint instances. Each type of point requires a set of coordinates, and a datum or grid respectively. GeoPoint and PlanePoint objects are defined on topologically distinct surfaces and so require a forward or inverse point projection to transform one to the other.
| Class | Coordinates | Description |
|---|---|---|
GeoPoint() |
(φ, λ) | decimal geographic latitude and longitude on geoid |
MGAPoint() |
(z, E, N) | z: grid zone designator, easting and northing meters in a Map Grid of Australia plane |
VICPoint() |
(E, N) | easting and northing in meters in a VICGRID plane |
MGRSPoint() |
(z, usi, x, y) | z: grid zone designator, usi: the 100,000-meter square identifier, easting and northing in meters |
To define a point, specify the coordinates and the datum/grid.
geo_pt = GeoPoint(φ=-37, λ=145, datum=GDA20)
mga_pt = MGAPoint(zone=54, lat_band='H', E=250,000, N=5,600,000, grid=MGA94)or use some of the provided utils to specify points from common reference systems. (e.g a 6 figure GR)
pt = MGRSPoint.from_6FIG(55, "H", "fu", "275882")
pt.transform_to(WGS84)Use the distance_to method on GeoPoint instances to compute geodesic distance across the surface of the reference ellipsoid. This method handles different datums by projecting to a common ellipsoid.
p1 = GeoPoint(dLat=-37.95103342, dLng=144.4248679, datum=GDA20)
p2 = GeoPoint(dLat=-37.65282114, dLng=143.9264955, datum=GDA94)
p1.distance_to(p2)
>>> 54972.274Use the distance_to method on a PlanePoint to compute grid distances.
Every instance of a point class can evaluate the grid convergence, magnetic declination and grid magnetic angle of it's position.
Install the latest release of isogonic-api from source at the following link if you need to run geomagnetic calculations. This is not required to use the rest of the functionality.
https://github.com/chompar4/isogonic-api
sf = 10,000
pt = MGAPoint(zone=54, lat_band='H', E=24 * sf, N= 250 * sf, grid=MGA20)
print(pt.declination, pt.grid_convergence, pt.grid_magnetic_angle)The relevant data for these maps can be grabbed by running
https://portal.spatial.nsw.gov.au/server/rest/services/Hosted/Topo_Map_Index/FeatureServer/0/query?text=&geometry&geometryType=esriGeometryEnvelope&inSR=&spatialRel=esriSpatialRelIntersects&relationParam=&objectIds=&where=objectid>-1&time=&returnCountOnly=false&returnIdsOnly=false&returnGeometry=false&maxAllowableOffset=&outSR=&outFields=mapnumber,mapname,mapseries,adjmapindexx,label,adjmapindexy&f=pjson
MGA Points can handle creation using the Brennan system of describing coordinates (see https://ozultimate.com/canyoning/track_notes/du_faur_creek.htm). These consist of a 6 Figure MGA Grid Reference and a Map Sheet Number (e.g '8930-1N' or 'Mount Wilson'). Only MGA coordinates are currently supported in this method. The following example gives the decimal coordinates of the start of Pipeline Canyon.
pt = MGAPoint.from_brennan('452278', '8931-1S')
dLat, dLng = pt.transform_to(pt.grid.datum)
Run buildkite agent using buildkite-agent start