<html><head><base href="x-msg://701/"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Robert this is really an openlayers question, but the answer is that you don't have to do anything other than configure the map options properly to have the displayProjection be EPSG:4326 and the projection EPSG:900913.<div><br></div><div>There should be plenty of examples out there of people using maps that let you use both google and other base layers (like OSM) on the same map. Here is how I do it</div><div><br></div><div><pre id="line91"><span class="Apple-tab-span" style="white-space:pre"> </span> var options = {
// the "community" epsg code for spherical mercator
projection: "EPSG:900913",
displayProjection: new OpenLayers.Projection("EPSG:4326"),
// map horizontal units are meters
units: "m",
// this resolution displays the globe in one 256x256 pixel tile
maxResolution: 78271.51695,
// these are the bounds of the globe in sperical mercator
maxExtent: new OpenLayers.Bounds(-20037508, -20037508,
20037508, 20037508)
,controls: [ new OpenLayers.Control.Navigation()]
};
// construct a map with the above options
map = new OpenLayers.Map('map', options);
</pre><div><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-style-span" style="font-family: monospace; white-space: pre; ">// create OSM layer</span></div><div><span class="Apple-style-span" style="font-family: monospace; white-space: pre; "></span><span class="Apple-style-span" style="font-family: monospace; white-space: pre; "> var osm = new OpenLayers.Layer.OSM.Osmarender("OSM Osmarender");</span></div><pre id="line91">
// create Google layer
var zoomlevels = 20;
var gmap = new OpenLayers.Layer.Google(</pre><pre id="line91"><span class="Apple-tab-span" style="white-space:pre"> </span>"Google Streets", // the default</pre><pre id="line91"> {numZoomLevels: zoomlevels, sphericalMercator: true}
);</pre><div><span class="Apple-tab-span" style="white-space:pre"> </span>// more layers here</div></div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-style-span" style="font-family: monospace; white-space: pre; ">// add the created layers to the map</span></div><pre id="line91"> map.addLayers([gmap, osm]);
</pre><div>Etc.</div><div><br></div><div>hth,</div><div>charles</div><div><br><div><div>On Mar 3, 2011, at 9:33 AM, Robert Buckley wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font-family: 'times new roman', 'new york', times, serif; font-size: 10pt; color: rgb(64, 0, 127); ">Hi,<br><br>I have my own topographic maps which I would like to use as base maps. They are in EPSG:4326<br><br>To display them with googlemaps would mean I would have to transform them on the fly into 900913, correct?<br><br>Does this bring any disadvantages? quality, loading time?...or should I reproject them in geoserver first?<br><br>thanks for any tips,<br><br>Robert<br></div></div></blockquote></div><br></div></body></html>