[OpenLayers-Users] how to use proj4js for Google

Wed Oct 15 13:44:54 EDT 2008

In case anyone else out there has been having trouble getting the
proj4js lib to do a coordinate transform, I have recently gone through
it with success.  I was goofing up a small part that caused much
problems.

I did one thing to solve my issue, 

1) make sure that I included the merc.js projCode in my header:

<script src="/html/scripts/proj4js/lib/projCode/merc.js"></script> 

So, the following is a page that will convert a latlon coord to google
(based on an original posting from this listserv):

<html>

<head>

<script src="/html/devlib/OpenLayers-2.7/lib/OpenLayers.js"></script>

<script src="/html/scripts/proj4js/lib/proj4js.js"></script>

<script src="/html/scripts/proj4js/lib/projCode/merc.js"></script>

</head>

<body>

<div id="map"></div>

<script type='text/javascript'>

<!-- \n";

    Proj4js.defs["EPSG:4326"] = "+proj=longlat +ellps=WGS84 +datum=WGS84
+no_defs";

    Proj4js.defs["EPSG:900913"] = "+proj=merc +a=6378137 +b=6378137
+lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null
+no_defs";

            var proj4326 = new OpenLayers.Projection("EPSG:4326");

            var projGoogle = new OpenLayers.Projection("EPSG:900913");

            var lon = -77.1266708374023;

            var lat = 37.6813888549805;

            var point = new OpenLayers.Geometry.Point(lon, lat);

            OpenLayers.Projection.transform(point, proj4326,
projGoogle);

            alert(lon + " " + lat + " = " + point.x +" "+ point.y);

// -->

</script>

</body>

</html>

Robert W. Burgholzer

Surface Water Modeler

Office of Water Supply and Planning

Virginia Department of Environmental Quality

rwburgholzer at deq.virginia.gov

804-698-4405

Open Source Modeling Tools:

http://sourceforge.net/projects/npsource/

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