geodesic

geodesic(D; step=0, unit=:m, np=0, proj::String="", epsg::Integer=0, longest::Bool=false)

or

geodesic(lon1, lat1, lon2, lat2; step=0, unit=:m, np=0, proj::String="", epsg::Integer=0, longest::Bool=false)

Generate geodesic line(s) (shortest distace) on an ellipsoid. Input data can be two or more points. In later case each line segment is descretized at step increments,

Parameters

  • D: - the input points. This can either be a GMTdataset (or vector of it), a Mx2 matrix, the name of file that can be read as a GMTdataset by gmtread() or a GDAL AbstractDataset object.

  • step: - Incremental distance at which the segment line is descretized in meters(the default), but see unit

  • unit: - If step is not in meters use one of unit=:km, or unit=:Nautical or unit=:Miles

  • np: - Number of intermediate points between poly-line vertices (alternative to step)

  • proj - If line data is in Cartesians but with a known projection pass in a PROJ4 string.

  • epsg - Same as proj but using an EPSG code.

  • longest - Compute the ‘long way around’ of the geodesic. That is, going from point A to B taking the longest path. But mind you that geodesics other than meridians and equator are not closed paths (see https://en.wikipedia.org/wiki/Geodesics_on_an_ellipsoid). This line is obtained by computing the azimuth from A to B, at B, and start the line at B with that azimuth and go around the Earth till we reach, close to A, but not exactly A (except for the simple meridian cases).

Returns

A Mx2 matrix with the lon lat of the points along the geodesic when input is a matrix. A GMT dataset or a vector of it (when input is Vector{GMTdataset}).

Example

Compute an geodesic between points (0,0) and (30,50) discretized at 100 km steps.

mat = geodesic([0 0; 30 50], step=100, unit=:k);

Source Code

This function has multiple methods: