[Gwt-openlayers-users] Reprojection of wns malyer and tranforming of point does not seem to work.

[John P. <byh...@gm...>]

I have a problem getting reprojection of wms layer maps working and I
would apprciate if someone could tell me what I'm doing wrong.

I have two maps in two different projections and I would like to
overlay them. I use the following code to do this.

//////////////////////////////////////////////////////////////////////////////////////////
MapOptions mapOptions = new MapOptions();
mapOptions.setNumZoomLevels(10);
mapOptions.setProjection("EPSG:3448");
mapOptions.setDisplayProjection(new Projection("EPSG:3448"));

mapOptions.setUnits("m");
mapOptions.setMaxExtent(new Bounds(100000, 100000, 900000, 700000));
mapOptions.setAllOverlays(true);
mapOptions.setMaxResolutionToAuto();

mapWidget = new MapWidget("100%", "100%", mapOptions);
add(mapWidget, new BorderLayoutData(LayoutRegion.CENTER));
Map map = mapWidget.getMap();

// Defining a WMS and adding it to the map
WMSParams wmsParams = new WMSParams();
wmsParams.setFormat("image/png");
wmsParams.setLayers("area1");
wmsParams.setIsTransparent(true);
wmsParams.setStyles("");

WMSOptions wmsLayerParams = new WMSOptions();
wmsLayerParams.setBuffer(0);
wmsLayerParams.setSingleTile(false);
wmsLayerParams.setMaxExtent(new Bounds(100000, 100000, 300000, 200000));
wmsLayerParams.setProjection("EPSG:24200");
WMS wmsLayer = new WMS("First map on old projection",
"http://localhost:8086/geoserver/wms", wmsParams, wmsLayerParams);

// Add layer to open layers map
map.addLayer(wmsLayer);

// Defining a WMS and adding it to the map
wmsParams = new WMSParams();
wmsParams.setFormat("image/png");
wmsParams.setLayers("area2");
wmsParams.setIsTransparent(true);
wmsParams.setStyles("");

wmsLayerParams = new WMSOptions();
wmsLayerParams.setBuffer(0);
wmsLayerParams.setSingleTile(false);
wmsLayerParams.setMaxExtent(new Bounds(500000, 500000, 800000, 700000));
wmsLayerParams.setProjection("EPSG:24200");
WMS wmsLayer = new WMS("Second map in new projection",
"http://localhost:8086/geoserver/wms", wmsParams, wmsLayerParams);

// Add layer to open layers map
map.addLayer(wmsLayer);

map.setCenter(new LonLat(400000, 400000));
//////////////////////////////////////////////////////////////////////////////////////////

The two maps hold data for adjacent areas but they are in different
projections. I want to be able to set the map display projection to
one of the projections, EPSG:3448 for instance, and re-project (on the
fly) the other map so I can overlay them. Hence I set the map display
projection to EPSG:3448, and when I am creating the wms layer I set
the srs of the request to the display projection. However I get an
empty map if I do this. When I set the projection of the wms request
to the projection of the data it contains then I get the map but it
has not been reprojected. I've searched for a simple reprojection
example to try and follow but I can't find any.

I've also noticed that if I try to tranform coordinates from one
projection to another I get no change. When I try the following code
the coordinates of the lonlat object remain the same instead of them
being offset by about 500000 for the x and y values.

LonLat pt = new LonLat(250000, 140000);
pt.transform("EPSG:3448", "EPSG:24200");

Do I need to include some extra javascripts to get the projection working.

Can anyone help me.

John