[Users] Programmatically changing the base map projection
Matt Priour
mpriour at kestrelcomputer.com
Mon Jun 27 14:58:21 CEST 2011
Glad to see that worked out for you. I didn't notice the restrictedExtent property on your base layer before.
Matt Priour
From: Hugo
Sent: Monday, June 27, 2011 5:18 AM
To: users at geoext.org
Subject: Re: [Users] Programmatically changing the base map projection
Hello again,
Just to give some feedback on this. I've manged to correctly reproject the map using the code suggestions that Matt pointed out. My problem was related with the restrictedExtent of the base map that was bot being reprojected. So, the only thing i've added to the code that Matt shared was the following:
map.restrictedExtent = newBase.restrictedExtent;
After this, evryhting works fine.
Once again, thanks for pointing me in the right direction.
Cheers,
Hugo
On Fri, Jun 24, 2011 at 3:45 PM, Hugo <hfpmartins at gmail.com> wrote:
Hi again,
I think i've spoken to early. Matt, after digging a little bit more, your code suggestions are givinig me the same results as my initial approach. The strange thing is that, using your code and firbug, i see that the Center coordinates and bounding box for maxExtent are being correctly reprojected. Nevertheless, the map is going to a different place on earth (see attached images: mercator is ok but etrs is completely out).
http://dl.dropbox.com/u/10817385/mercator.png
http://dl.dropbox.com/u/10817385/etrs.png
No errors are shown in firebug and i'm a little bit lost. I have defined the etrs layer like the following:
var ortos = new OpenLayers.Layer.TileCache(
'Ortofotomapas ARH',
'http://localhost/tilecache',
'Ortos',
{
isBaseLayer: true,
maxExtent: bBoxEtrs,
serverResolutions: mapResolutionsEtrs,
visibility: false,
transparent: true,
scales: [800000, 500000, 250000, 100000, 50000, 25000, 10000, 5000, 2500, 1000],
maxResolution:282.2220733500804,
minResolution: 0.35277758727788067,
units: 'm',
projection: etrs,
restrictedExtent: bBoxEtrs
}
);
I'm sure that this tilecache layer is working properly because i've tested it on a simple openlayers app configured with the same options.
Any hints on what might be happening??? Unfortunately, i can't see what is going wrong and have no more alternative ideas.
Cheers,
Hugo
On Tue, Jun 21, 2011 at 2:42 PM, Hugo <hfpmartins at gmail.com> wrote:
Hi Matt,
That works like a charm ;)
Really, thanks a lot for this suggestion and code!
Cheers,
Hugo
On Mon, Jun 20, 2011 at 8:29 PM, Matt Priour <mpriour at kestrelcomputer.com> wrote:
I've had similar problems and I've solved it by adding an event listener to the map's baselayerchange event.
you would put mapOptionsEtrs properties on the Etrs base layer rather than on the map. Map options are most ignored and overwritten by base layer options.
here is my baselayerchange event handler, which is called with the map as scope.
function onBaseLayerChange(evtObj){
var mapProj, baseProj, map, newBase, reproject;
map = this;
newBase = evtObj.layer;
mapProj = (map.projection && map.projection instanceof OpenLayers.Projection) ? map.projection : new OpenLayers.Projection(map.projection);
baseProj = newBase.projection;
reproject = !(baseProj.equals(mapProj));
if (reproject) {
var center, maxExt;
//calc proper reporojected center
center = map.getCenter().transform(mapProj, baseProj);
//calc correct reprojected extents
maxExt = newBase.maxExtent;
//set map projection, extent, & center of map to proper values
map.projection = baseProj;
map.maxExtent = maxExt;
map.setCenter(center);
}
}
Matt Priour
Kestrel Computer Consulting
From: Hugo
Sent: Monday, June 20, 2011 12:45 PM
To: users at geoext.org
Subject: [Users] Programmatically changing the base map projection
Dear Geoext users,
I'm trying to develop a functionality that will allow the user to change the base map projection. The initial map is using the spherical mercator projection so that OSM and Google/Yahoo/Bing layers can be displayed. Because the users will need to edit features at specific scales (1:25.000; 1:10.000) i need to develop a function that will change the projection from spherical mercator to ETRS PTM06 (EPSG:3763). I think i'm almost there but somehow, after reprojection the base map i get my map full extent much higher in latitude (so, more to the north) and much smaller in longitude (more to the west).
My steps are:
1. Remove all OSM/Google/Yahoo/Bing layers from the map.
2. Add new options to the map
3. Merge new options (projection) to a blank layer and set it as basellayer
4. Loop the remaining layers and add new options.
The relevant part of the code is below:
//Map options
var mapOptions = {
maxExtent: bBox,
maxResolution: 305.74811309814453,
minResolution: 0.29858214169740677,
resolutions: mapResolutions,
units: 'm',
projection: baseMercator,
displayProjection: wgs,
restrictedExtent: bBox,
panMethod: OpenLayers.Easing.Quad.easeOut,
numZoomLevels: 20,
controls: []
};
var mapOptionsEtrs = {
maxExtent: bBoxEtrs,
maxResolution: 282.2220698223045,
minResolution: 0.35277758727788067,
resolutions: mapResolutionsEtrs,
units: 'm',
projection: etrs,
displayProjection: etrs,
restrictedExtent: bBoxEtrs,
panMethod: OpenLayers.Easing.Quad.easeOut,
numZoomLevels: 10,
};
//Reprojection logic
var radioValue = Ext.getCmp('srsradiogroup').getValue().getGroupValue();
var mapProj = map.getProjection();
var baseCart = treePanel.getNodeById('basecartography');
if (radioValue != mapProj && radioValue == 'EPSG:3763') {
baseCart.cascade(function () {
var childNodes = this.childNodes;
for (i = 0; i < childNodes.length; i++) {
switch (childNodes[i].text) {
case 'OpenStreetMap':
childNodes[i].disable();
map.removeLayer(osm);
break;
case 'Google Streets':
childNodes[i].disable();
map.removeLayer(gstreets);
break;
// and so on...
}
}
});
map.setOptions(mapOptionsEtrs);
map.layerContainerOrigin.transform(baseMercator, etrs);
blankLayer.addOptions({
projection: etrs
});
map.setBaseLayer(blankLayer);
for (i = 0; i < mapPanel.map.layers.length; i++) {
var className = mapPanel.map.layers[i].CLASS_NAME;
if (className == 'OpenLayers.Layer.WMS') {
mapPanel.map.layers[i].addOptions({
srs: etrs
});
} else if (className == 'OpenLayers.Layer.Vector') {
mapPanel.map.layers[i].projection = etrs;
} else {
//here i will control other types of layers like tilecache
}
}
}
Checking the map and layers projection through firebug, it seems everything is correct.
I've also tried to get the initial extent of the map, reproject it and zoom to it after the reprojection but the it still goes to the same place.
What might be the issues here?? Am i doing something completely wrong?
Cheers,
Hugo
--
Hugo Martins
LabNT - ISEGI UNL
Campus de Campolide
1070-312 Lisboa
N 38°43'56.84", W 9°9'35.74"
--
Hugo Martins
LabNT - ISEGI UNL
Campus de Campolide
1070-312 Lisboa
N 38°43'56.84", W 9°9'35.74"
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