Transform coordinates EPSG:32628 to EPSG:3857 Openlayers 3

Question

I need to transform the example coordinates to a different projection in Openlayers3, the EPSG:32628 to EPSG:3857. I made a function to do it but the result is exactly the same numbers.

function plsHelp(){
    var pt = [459123.1209, 3108334.7701];
    var scr = new ol.proj.Projection('EPSG:32628');
    var dest = new ol.proj.Projection('EPSG:3857');
    var test= ol.proj.transform(pt,scr,dest);
    console.log(test);
}

What is wrong with the function that is preventing the tranformation of the coordinates from EPSG:32628 to EPSG:3857 in Openlayers 3?

Answer 1

OpenLayers natively includes the two following projections only: EPSG:3857 and EPSG:4326. To be able to transform to or from any other projections, you must use the Proj4JS library.

Try adding the two following scripts, the first being the Proj4JS library itself, the other the definition of the EPSG:32628 projection:

<script src="https://cdnjs.cloudflare.com/ajax/libs/proj4js/2.4.3/proj4.js"></script>
<script src="http://epsg.io/32628.js"></script>

Answer 2

If it is the projection view only, you could define it right at beginning when you initiate the ol.view. code like:

   var view = new ol.View({
      //change projection to WGS84 
      projection: "EPSG:4326",
      center: [-98.5284468774974,50.71391708013823],
            zoom: 8
    });

If you'd like to do a actual conversion, you could use openlayer's ol.proj.transform, from here. Code like below:

var oldCode = OSM_layer.getSource().getProjection().getCode(); // Getting projection of target layer 
newCoord = ol.proj.transformExtent([extent.j[0], extent.j[1], extent.j[2], extent.j[3]], oldCode, 'EPSG:4326'); // perform projection transform with given extent.