reproject

Reproject GeoJSON from one projection/CRS to another

npm install reproject
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reproject

Takes GeoJSON in one projection/CRS and transforms, or reprojects, it to another.

cli

install:

$ npm install -g reproject

use:

$ echo '{"type":"Point","coordinates":[319180, 6399862]}' | reproject --use-spatialreference --from=EPSG:3006 --to=EPSG:4326

Options:

  • --from=crs-name is the CRS to convert the GeoJSON from
  • --to=crs-name is the CRS to convert the GeoJSON to
  • --use-spatialreference or --sr to use spatialreference.org to look up any CRS definitions that aren't already known
  • --crs-defs=file to provide a JSON dictionary of known CRS definitions. A sample file of CRS definitions, crs-defs.json, is supplied.
  • --reverse to reverse the axis (swap x and y) before performing the reprojection

reproject can be used together with for example wellknown and geojsonio-cli:

$ echo "POINT(319180 6399862)" | wellknown | reproject --crs-defs=crs-defs.json --from=EPSG:3006 --to=EPSG:4326 | geojsonio

usage

Installation is easy with npm:

npm install reproject

It works well in the browser with for example browserify.

api

reproject(geojson, from, to, crss)

Reprojects the given GeoJSON from the CRS given in from to the CRS given in to.

The from and to arguments can either be a proj4 projection object, or a string containing a CRS name. In the case of a CRS name, the proj4 projection instance is looked up using the crss argument. crss is assumed to be a dictionary of projection names to proj4 objects.

If from is left undefined or null, the CRS will be detected from the GeoJSON's crs property and looked up in the crss dictionary.

toWgs84(geojson, from, crss)

Shortcut equivalent to

reproject(geojson, from, proj4.WGS84, crss)

detectCrs(geojson, crss)

Detects the CRS defined in the given GeoJSON and returns the corresponding proj4 projection instance from crss. If no CRS is defined in the GeoJSON, or the defined CRS isn't present in crss, an error is thrown.

reverse(geojson)

Reverses the axis order of the coordinates in the given GeoJSON, such that x becomes y and y becomes x.

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