https://github.com/phrogz/svg2geojson

Converts an SVG file with added geo-referencing tags into one or more GeoJSON files.
https://github.com/phrogz/svg2geojson

Last synced: 12 days ago
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Converts an SVG file with added geo-referencing tags into one or more GeoJSON files.

• Host: GitHub
• URL: https://github.com/phrogz/svg2geojson
• Owner: Phrogz
• License: mit
• Created: 2017-06-16T13:54:56.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2023-04-10T19:15:58.000Z (over 1 year ago)
• Last Synced: 2024-10-26T12:34:51.612Z (13 days ago)
• Language: JavaScript
• Size: 24.4 KB
• Stars: 59
• Watchers: 4
• Forks: 30
• Open Issues: 12
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# SVG 2 GeoJSON

Converts an SVG file with added geo-referencing tags into one or more GeoJSON files.

## Installing

`npm install svg2geojson`

## Geo-Referencing Tags

You must place two `GeoItems` inside a [Prognoz MetaInfo](http://help.prognoz.com/8.0/en/mergedProjects/Specifications/svgmapspecification/structure/svgmap_structure.htm) element as a direct child of the `` element at the root of your document.

~~~xml

  

  

~~~

These map opposing X/Y corners in your SVG coordinate space to Longitude/Latitude coordinates on the world. _Note that the SVG coordinate space has Y increasing down (toward the south), while Latitude increases upwards (towards the north)._

## Usage

**Running the binary from the command line**:

~~~

$ npm install -g svg2geojson

$ svg2geojson file.svg          # Writes file.geojson

$ svg2geojson file.svg --layers # Writes file.geojson, file-layer1Name.geojson, …

# See svg2geojson --help for more parameters

~~~

**Running as a Node.js library**:

~~~ js

const { geoFromSVGFile, geoFromSVGXML } = require('svg2geojson.js');

// …reading from file on disk

geoFromSVGFile( 'my.svg', layers => {

	layers.forEach( layer => {

		let json = JSON.stringify(layer.geo); // Turn JS object into JSON string

		console.log(`Layer Named: "${layer.name}"`);

		console.log(json);

	});

}, {layers:true, tolerance:0.5} );

// …processing SVG code as a string

const svg = ``;

geoFromSVGXML( svg, layer => {

	let json = JSON.stringify(layer.geo); // Turn JS object into JSON string

	console.log(json);

} );

~~~

See the output of `svg2geojson --help` for the options you can pass to the functions, and their default values.

## Preparing Paths

SVG allows `` elements with an arbitrary number of overlapping subpaths, with some of them being 'positive' space and some 'negative' space. In SVG these subpaths may be oriented clockwise or counter-clockwise, and added in any order.

GeoJSON only allows a `Polygon` to have a single 'positive' subpath (and an arbitrary number of additional 'hole' subpaths). To make it easier for the code to detect which subpath is the 'positive' subpath you must currently:

1. Have only one positive subpath per ``.

2. Ensure that the positive subpath is the first subpath in a ``.

## TODO (AKA Known Limitations)

* Support modes of projection unmapping

* Support non-rectangular, inverse bilinear unmappings

* Add more command-line options to control JSON formatting.

* Treat `` as `MultiPolygon`, `GeometryCollection`, or `MultiLineString` as appropriate. Currently items within a group are flattened as individual `Feature` items in the GeoJSON.

* Treat `` with multiple positive subpaths as a `MultiPolygon`. (This requires figuring out which holes apply to which positive subpaths.)