reproject

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 --crs-defs=crs-defs.json --from=EPSG:3006 --to=EPSG:4326

A sample file of CRS definitions, crs-defs.json, is supplied. Its contents is a dictionary of CRS names to Proj4 definitions.

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

Sometimes your data has reversed the axis order such that x has become y and vice versa. reproject can help you get them in the correct order before transforming by using the --reverse argument:

$ echo '{"type":"Point","coordinates":[6399862, 319180]}' | reproject --reverse --crs-defs=crs-defs.json --from=EPSG:3006 --to=EPSG:4326

usage

reproject currently only works with node.js, since proj4node, which reproject relies on, does not play nice with for example browserify. Installation is easy with npm:

npm install reproject

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 proj4node projection object, or a string containing a CRS name. In the case of a CRS name, the proj4node projection instance is looked up using the crss argument. crss is assumed to be a dictionary of projection names to proj4node 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, proj4node.WGS84, crss)

detectCrs(geojson, crss)

Detects the CRS defined in the given GeoJSON and returns the corresponding proj4node 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.