[GIS] Getting wrong lat/lang after transforming from “EPSG:900913” projection to “EPSG:4326”

openlayers

In OpenLayer3 Map I'm getting lat/lang from nominatim and the map is in "EPSG:900913" projection and then transforming it to "EPSG:4326" projection .

if lat = 12.9791198 and lang = 77.5912997 then i am transforming like this,

var point = new ol.geom.Point([lan,lat]);
point.transform("EPSG:4326","EPSG:900913");

After transformation lat/lang should be [8643375.747091185,1460888.081802196] but i am getting [8637423.97259228,-13864431.524951909].

Best Answer

While creating the point instance

var point = new ol.geom.Point([lon,lat]);

lon and lat value should be in numeric format previously they were in string format hence it was converting into wrong lat and long.

Related Solutions

[GIS] How to convert drawn vector feature from EPSG:900913 to EPSG:4326

You need to project (transform) the shape from EPSG:900913 (actually use the standard EPSG:3857) to EPSG:4326.

You can use the following code:

var gcs=new OpenLayers.Projection("EPSG:4326");
var webMercator=new OpenLayers.Projection("EPSG:3857");

/*I am assuming that you have a polygon in web mercator. You can do this for points and lines as well*/
var polygon_wgs84=poly.transform(webMercator, gcs);

//now you can convert the polygon to wkt
console.log(polygon_wgs84.toString(););

[GIS] Reprojecting vector layer from EPSG 3857 to 4326

I am not totally sure if I understand what you want to do. But when calling writeFeatures on a format, you can specify the dataProjection (the projection you want to have in your output format) and the featureProjection (the projection of your features that you want to export). See ol.format.GeoJSON.writeFeatures.

So for example if your features are in 'EPSG:4326' and you want to have a GeoJSON in 'EPSG:3857', you would do:

var geoJson3857 = new ol.format.GeoJSON.writeFeatures(features4326, {
  dataProjection: 'EPSG:3857',
  featureProjection: 'EPSG:4326'
});

Best Answer

Related Solutions

[GIS] How to convert drawn vector feature from EPSG:900913 to EPSG:4326

[GIS] Reprojecting vector layer from EPSG 3857 to 4326

Related Question