Re: [Geoserver-users] Reprojection and OpenLayers

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Hi, Justin--

Thanks so much, this is exactly what I need!

Have a good weekend.

-- Ethan

At 04:00 PM 3/20/2009, Justin Deoliveira wrote:
>Hi Ethan,
>
>I believe this problem is occurring because you are still using 
>geographic coordinates for the bounding box, but specifying the srs 
>to the albers projection. To get it right you have to convert the 
>bbox coordinates to albers.
>
>Now luckily there is a tool in GeoServer that can help --> the wms 
>reflector. It is a convenience for making wms requests that prevents 
>you from having to fill out all the parameters. It will also set up 
>the bbox parameter in the proper coordinates based on the srs.
>
>So... the following request is the states in geographic (EPSG:4326)
>
>http://localhost:8080/geoserver/wms/reflect?layers=topp:states&format=image/svg+xml
>
>To change to the albers projection just add the srs parameter:
>
>http://localhost:8080/geoserver/wms/reflect?layers=topp:states&format=image/svg+xml&srs=epsg:45556
>
>Or 42303, i tried both and they both worked for me.
>
>If you do need to make the full WMS requests you need to change the 
>bbox parameter so its in albers coordinates. For instance:
>
>bbox=-2353760.17599943,-1294266.91959374,2253944.09170884,1561261.68522241&srs=epsg:45556 
>
>
>in the request you showed above should get you the results you are 
>looking for.
>
>-Justin
>
>
>Ethan Goldstine wrote:
>>Hi--
>>Thanks for your advice.
>>I decided to do another test and take OL out of the equation.
>>I started with this link from the built-in demo:
>>http://localhost:8080/geoserver/wms?bbox=-127.61950064999999,23.7351786,-64.08177035,50.592523400000005&styles=&Format=image/svg%2Bxml&request=GetMap&version=1.1.1&layers=topp:states&width=800&height=317&srs=EPSG:4326 
>>
>>That worked.
>>I then changed the srs to 45556 and all I see is Kansas.  (It's a 
>>peach-colored rectangle labeled KS... not sure if it's the right 
>>dimensions of Kansas.)
>>When I change the srs to 42303 I get nothing.
>>Do you see anything strange in the SVG request?
>>-- Ethan
>>
>>At 08:57 PM 3/18/2009, you wrote:
>>>Hi Ethan,
>>>
>>>You may get better luck on the open layers mailing list but a 
>>>couple of things I noted.
>>>
>>>I think you have to set the projection property on the wms layer, 
>>>rather then the map. I also believe you will have to set the 
>>>extent of the layer explicitly as well.
>>>
>>>What version of openlayers are you using. Looking at the WFS 
>>>request a few things are off. The first is the SRS parameter, in 
>>>wfs this should be SRSNAME. I recognize this problem from a while 
>>>back. I think you will get some better results with a more recent 
>>>version of OL.
>>>
>>>Also of note is that officially reprojection is not support with 
>>>wfs version 1.0, only 1.1. Although GeoServer does support it for 1.0 as well.
>>>
>>>-Justin
>>>
>>>Ethan Goldstine wrote:
>>>>Hi--
>>>>I'm having some difficulty getting GeoServer to do reprojection 
>>>>to an Albers Equal Area map.  I think the correct codes are EPSG: 
>>>>42303 and 45556 (though I could be wrong).
>>>>As a test, I'm using the states data that comes with Geoserver.
>>>>I've tried both WMS and WFS.
>>>>Here's the code:
>>>>  var map;
>>>>         function init(){
>>>>             map = new OpenLayers.Map('map',{projection: new 
>>>> OpenLayers.Projection("EPSG:42303")});  // Note that I've also tried 45556
>>>>             var political = new OpenLayers.Layer.WMS(
>>>>                 "State",
>>>>                 "/geoserver/wms",
>>>>                 {layers: 'topp:states',
>>>>                  format: 'image/png'}
>>>>             );
>>>>
>>>>             var states= new OpenLayers.Layer.WFS(
>>>>                 "States",
>>>>                 "/geoserver/wfs",
>>>>                 {typename: 'topp:states'},
>>>>                 {
>>>>                     typename: 'states',
>>>>                     featureNS: ' http://www.openplans.org/topp',
>>>>                     extractAttributes: false,
>>>>                     isBaseLayer: true
>>>>                 }
>>>>             );
>>>>             states.style = 
>>>> OpenLayers.Util.applyDefaults({strokeColor: "#0000ff"},
>>>>                     OpenLayers.Feature.Vector.style["default"]);
>>>>             map.addLayers([political,states);
>>>>
>>>>I've done testing just showing one layer at a time and here's what happens:
>>>>1.      political (WMS) with EPGS: 42303
>>>>Displays nothing.  I se a JS error message:
>>>>userAgentButton is null
>>>>_hasString() <??>()OpenLayers.js (line 224)
>>>>OpenLayers.js() <??>()OpenLayers.js (line 223)
>>>>[] var factory=null;if(typeof 
>>>>GearsFactory!...documentElement.appendChild(factory);}}}
>>>>
>>>>2.      states (WFS) with EPGS: 42303
>>>>Query: 
>>>>http://localhost:8080/geoserver/wfs?typename=topp%3Astates&SERVICE=WFS&VERSION=1.0.0&REQUEST=GetFeature&SRS=EPSG%3A42303&BBOX=-575,-306.801875,550,361.166875 
>>>><http://localhost:8080/geoserver/wfs?typename=topp%3Astates&SERVICE=WFS&VERSION=1.0.0&REQUEST=GetFeature&SRS=EPSG%3A42303&BBOX=-575,-306.801875,550,361.166875> 
>>>>
>>>>I see the state outlines but it's not an Albers projection.
>>>>3.      political (WMS) with EPGS: 45556
>>>>I see the same JS error as in case 1, query to the db happens and 
>>>>I only see Kansas.
>>>>Note that if I remove the projection from OpenLayer.Map(... it works fine.
>>>>4.      states (WFS) with EPGS: 45556
>>>>Query: 
>>>>http://localhost:8080/geoserver/wfs?typename=topp%3Astates&SERVICE=WFS&VERSION=1.0.0&REQUEST=GetFeature&SRS=EPSG%3A45556&BBOX=-575,-306.801875,550,361.166875 
>>>><http://localhost:8080/geoserver/wfs?typename=topp%3Astates&SERVICE=WFS&VERSION=1.0.0&REQUEST=GetFeature&SRS=EPSG%3A45556&BBOX=-575,-306.801875,550,361.166875> 
>>>>
>>>>Same as case 2, no Albers projection.
>>>>Any help and advice is greatly appreciated.
>>>>-- Ethan
>>>>Ethan Goldstine
>>>>Producer, kapow, inc.
>>>>et...@ka...
>>>>
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>>>
>>>
>>>--
>>>Justin Deoliveira
>>>OpenGeo - http://opengeo.org
>>>Enterprise support for open source geospatial.
>>Ethan Goldstine
>>Producer, kapow, inc.
>>et...@ka...
>>310.394.5276 (394-KAPOW)
>
>
>--
>Justin Deoliveira
>OpenGeo - http://opengeo.org
>Enterprise support for open source geospatial.

Ethan Goldstine
Producer, kapow, inc.
et...@ka...

310.394.5276 (394-KAPOW)