[OpenLayers-Users] transform help please
Dash
jimlug at co.clackamas.or.us
Thu Nov 19 14:28:53 EST 2009
Thanks for the quick response Richard, but I don't see how I'm re-projecting
raster layers when I'm explicitly specifying coordinates to transform? I'm
only using the transformation on coordinates, not the base layers (Google).
Ahhh, I just figured it out. Here is what I had to do in-order to transform
coordinates from EPSG:2913 (Stateplane) to EPSG:900913. Within the head tag
I added 2 projCodes (lcc.js and merc.js).
<script src="./proj4js/lib/proj4js.js"></script>
<script src="./proj4js/lib/proj4js-compressed.js"></script>
<script src="./proj4js/lib/defs/EPSG2913.js"></script>
<script src="./proj4js/lib/projCode/lcc.js"></script>
<script src="./proj4js/lib/projCode/merc.js"></script>
Also, here is my transformation:
var srcProj = new OpenLayers.Projection("EPSG:2913");
var destProj = new OpenLayers.Projection("EPSG:900913");
var point = new OpenLayers.LonLat(7662464.286, 614886.646);
point.transform(srcProj, map.getProjectionObject());
My input coordinates were: 7662464.286, 614886.646
Transformed coordinates: -13647631.260266263, 5674262.881180859
Works great, at least for now.
Richard Marsden wrote:
>
> It looks like you are trying to re-project Google raster layers?
>
> I thought OpenLayers was only capable of re-projecting vector layers?
>
> For example, the following article uses OpenLayers (& Proj4JS) to
> re-project
> KML and GeoRSS data (geographic coords, WGS84) to a number of different
> projections (Mollweide, Behrmann, etc):
>
> http://www.geowebguru.com/articles/209-how-to-create-an-online-map-with-a-non-mercator-projection-part-2
>
>
> Richard Marsden
> Winwaed Software Technology LLC
> http://www.winwaed.com
> http://www.mapping-tools.com
> http://www.geowebguruc.om
>
>
> On Thu, Nov 19, 2009 at 12:12 PM, Dash <jimlug at co.clackamas.or.us> wrote:
>
>>
>> Aloha Thursday folks,
>>
>> I am banging my head against the problem for the last several hours. I
>> have
>> went through numerous examples and utilized OpenLayers tutorial on
>> reprojecting points without any success. I've even used the Proj4js Wiki
>> without any help. Could some please shed some light on what I am doing
>> wrong?
>>
>> Here is the scenario. I am trying to transform some coordinates from
>> EPSG:2913 to EPSG:900913. I've also tried a simplified version using
>> EPSG:4326 -> EPSG:900913. Anyway, the transform is not happening for
>> some
>> odd reason. I do have the proj4js library within my code and I have
>> added
>> EPSG definition to my /proj4js/lib/def directory. I am checking if the
>> projection by using the getUnits function of the projection class within
>> OpenLayers. If the units come back null, then the proj4js library is
>> unavailable. Why is this? I'm so confused. This should be rather
>> straight
>> forward. Anyway, here is some of my code. Hopefully someone can help me
>> out. Thanks.
>>
>> <head>
>> <script src="http://openlayers.org/dev/lib/OpenLayers.js"
>> type="text/javascript"></script>
>> <script src="./proj4js/lib/proj4js.js"></script>
>> <script src="proj4js/lib/defs/EPSG2913.js"></script>
>> <script src="proj4js/lib/defs/EPSG900913.js"></script>
>> <script src="proj4js/lib/defs/EPSG4326.js"></script>
>> </head>
>>
>> <script type="text/javascript">
>> var map;
>> function init(){
>> var options = {
>> //projection: new OpenLayers.Projection("EPSG:900913"),
>> // Map projection
>> projection: "EPSG:900913",
>> displayProjection: new OpenLayers.Projection("EPSG:4326"),
>> // Display
>> projection
>> units: "m",
>> numZoomLevels: 5,
>> maxResolution: 156543.0339,
>> maxExtent: new OpenLayers.Bounds(-13698618.8209569,
>> 5595988.4768255,
>> -13521569.8682338, 5701506.49106001)
>> };
>>
>> // Initiate Map Controls
>> map.addControl(new OpenLayers.Control.LayerSwitcher());
>> map.addControl(new OpenLayers.Control.MousePosition());
>>
>> // Create Google Mercator Layers
>> var gmap = new OpenLayers.Layer.Google("Google
>> Streets",{'sphericalMercator': true, numZoomLevels: 20});
>> var gphy = new OpenLayers.Layer.Google("Google Physical",
>> {'sphericalMercator': true, type: G_PHYSICAL_MAP, numZoomLevels: 20});
>> var gsat = new OpenLayers.Layer.Google("Google
>> Satellite",{'sphericalMercator': true, type: G_SATELLITE_MAP,
>> numZoomLevels:
>> 20});
>> var ghyb = new OpenLayers.Layer.Google("Google
>> Hybrid",{'sphericalMercator': true, type: G_HYBRID_MAP, numZoomLevels:
>> 20});
>>
>> map.addLayers([gmap, gphy, gsat, ghyb]);
>>
>> var srcProj = new OpenLayers.Projection("EPSG:4326");
>> alert(srcProj.getUnits());
>> var point = new OpenLayers.LonLat(-71, 42);
>> point.transform(srcProj, map.getProjectionObject());
>>
>> if(point.transformed)
>> {
>> alert("point already transformed");
>> }
>>
>> Proj4js.transform(srcProj, map.getProjectionObject(), point);
>>
>> Any suggestions would be greatly appreciated. THANKS...
>> --
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