Chinese Coordinate Transform

Coordinate or GeoJSON trasnforming from WGS84 to various encrypted Chinese coordinate systems such as BD09LL, GCJ02 and vice versa.

Supported coordinate reference systems (CRS)

* GCJ02 : Chinese encrypted coordinate system
* BD09LL : CRS used by http://map.baidu.com
* WGS84 : well-known CRS, aka EPSG:4326

Definition

``javascript
convertor.transform(source, fromCRS, toCRS);
`

* source : a coordinate, array of coordinates, a GeoJSON or a array of GeoJSON to transform, possible values:
- a coordinate: [x, y]
- coordinate arrays: [[x1,y1], [x2, y2]]
or more dimensions: [[[x1,y1], [x2, y2], [x3, y3]]]
- a geoJSON object: { "type": "Point", "coordinates": [100.0, 0.0] }
- a array of geoJSON objects:
[{ "type": "Point", "coordinates": [100.0, 0.0] } ,
{ "type": "Point", "coordinates": [101.0, 1.0] }]
* fromCRS : CRS transform from, possble values:
- 'gcj02'
- 'bd09ll'
- 'wgs84' | 'EPSG:4326'
* toCRS : CRS transform to, same possible values with fromCRS

How to use

$3

`Bash
npm install chncrs
`

$3

`html


`

Example

`javascript
var convertor = require('chncrs');
//convert coordinates from gcj02 to bd09ll
var c = convertor.transform([114.68837663801743, 33.63312016454496], 'GCJ02', 'BD09LL');

//convert a geoJSON object from gcj02 to bd09ll
//can also be other geometry type, a Feature, even a FeatureCollection
var geo = { "type": "Point", "coordinates": [100.0, 0.0] };
var geo2 = convertor.transform(geo, 'GCJ02', 'BD09LL');


//a geoJSON array
var geos = [{ "type": "Point", "coordinates": [100.0, 0.0] } ,
{ "type": "Point", "coordinates": [101.0, 1.0] }];
var geos2 = convertor.transform(geo, 'GCJ02', 'BD09LL');

//a Feature
var feature = { "type": "Feature",
"geometry": {"type": "Point", "coordinates": [102.0, 0.5]},
"properties": {"prop0": "value0"}
};
var feature2 = convertor.transform(geo, 'GCJ02', 'BD09LL');

//a FeatureCollection
var featureCollection = {
"type": "FeatureCollection",
"features": [
{ "type": "Feature",
"geometry": {"type": "Point", "coordinates": [102.0, 0.5]},
"properties": {"prop0": "value0"}
},
{ "type": "Feature",
"geometry": {
"type": "LineString",
"coordinates": [
[102.0, 0.0], [103.0, 1.0], [104.0, 0.0], [105.0, 1.0]
]
}
]
};
var featureCollection2 = convertor.transform(geo, 'GCJ02', 'BD09LL');
``