azogheb / kml-polygon-to-svg

Converts KML Placemark elements into SVG path elements. (proof of concept)

kml-polygon-to-svg.js

This tool can convert KML files containing Placemarks and Polygons into SVG path elements.
The main task is to convert coordinates from spherical to cartesian using a projection.

Usage :

var KPTS = require("../dist/index.js");
var fs = require("fs");

var kmlFileName = "./input.kml";
var outputFileName = "./output.svg";

var kml = fs.readFileSync(kmlFileName, 'utf8');

fs.writeFileSync(outputFileName, KPTS(kml));

This tool will also look for <Data> elements in Placemarks and will add them as attributes to the path elements in the output. By default, the name of the Data element is prefixed by "data-", which helps avoid conflicts but is not standard (as of SVG 1.1). You can override the prefix with the dataPrefix option, which you can use to use a prefix such as "mynamespace:" if you want to add your namespace (you will have to declare your namespace in the svg tag).

The standard spherical mercator projection is used by default.
Other projections are implemented :

• equirectangular : very simple but usually not recommended. You will have to provide a latitude close to the center of the area you want to project
• elliptical mercator : more precise than spherical mercator, but heavier.

KPTS(kml, {
   projection: "equirectangular",
   φ0: 42.01
});
KPTS(kml, {
   projection: "ellipticalMercator"
});

TODO

• write tests
• refactor viewport calculation (ugly right now)
• provide options to transform coordinates and extended data with custom functions
• include an example