Returns a new Proj projection specification object for a given PROJ.4 parameter list.

Returns {:ok, proj} on success, or {:error, "reason"} if the PROJ.4 parameter string is invalid.

Examples

Proj.from_def("+init=epsg:4326")

Proj.from_def("+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs")

Proj.from_def("+init=world:bng")

Proj.from_def("+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000
               +y_0=-100000 +ellps=airy +datum=OSGB36 +units=m +no_defs")

See https://trac.osgeo.org/proj/wiki/GenParms for documentation on how these parameter lists.

One way of finding the the PROJ.4 parameter list you require is to search http://spatialreference.org/ for your desired CRS and find the PROJ.4 parameter list under the "Proj4" link on a CRS's page.

Returns a Proj object for a given EPSG code from the EPSG Geodetic Parameter Dataset.

Returns {:ok, proj} on success, or {:error, "reason"} if the EPSG definition is not found.

Proj.from_epsg(4326) # WGS84
Proj.from_epsg(27700) # British National Grid

Returns a Proj object for a given known PROJ.4 init file definition.

Returns {:ok, proj} on success, or {:error, "reason"} if the definition is not found.

On Linux, by default, these definitions should be stored in /usr/share/proj/ with your PROJ.4 installation.

Proj.from_known_def("epsg", "4326") # WGS84
Proj.from_known_def("world", "bng") # British National Grid

Converts a given WGS84 {latitude, longitude} pair in degrees to the equivalent {easting, northing} in the CRS proj.

This function raises on error, unlike Proj.transform/3.

This is a convenience function for a common use case of Proj.

iex> {:ok, bng} = Proj.from_epsg(27700)
{:ok, #Proj<+init=epsg:27700 ...>}
iex> Proj.from_lat_lng!({51.501479, -0.140631}, bng)
{529155.0658918166, 179698.9583449281}

Returns the def string given to create the given Proj object, expanded to its fullest form if possible.

iex> Proj.get_def(Proj.wgs84)
" +init=epsg:4326 +proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0"

Turns a {longitude_radians, latitude_radians, z} tuple into {longitude_degrees, latitude_degrees, z}.

Converts a given {easting, northing} pair and its CRS proj to a WGS84 {latitude, longitude} pair, where latitude and longitude are in degrees.

This function raises on error, unlike Proj.transform/3.

This is a convenience function for a common use case of Proj.

iex> {:ok, bng} = Proj.from_epsg(27700)
{:ok, #Proj<+init=epsg:27700 ...>}
iex> Proj.to_lat_lng!({529155, 179699}, bng)
{51.50147938477216, -0.1406319210455952}

Turns a {longitude_degrees, latitude_degrees, z} tuple into {longitude_radians, latitude_radians, z}.

Transforms coordinates from one Proj CRS to another.

Coordinates are given in the order {x, y, z}, or for geographic coordinates, {longitude, latitude, z}, where z is the altitude above the geoid of the CRS. longitude and latitude must be given in radians. Proj.to_rad/1 may be helpful if you have coordinates in degrees.

Returns {:ok, {x, y, z}} on success, or {:error, "reason"} if the PROJ.4 library was unable to perform a transformation. If geographic coordinates are returned, they will be in the order {longitude, latitude, z}, and will be in radians.

Returns a Proj object for the WGS84 geographic coordinate reference system.

WGS84 is the standard coordinate system used for GPS and is most likely what you need when working with {latitude, longitude} coordinates.