[OpenLayers-Users] WMS, Google Map, and Vector Layer

[Arnd Wippermann]

Hi Chris,

There are a couple of reasons for what you see or not see

1. map creation without options will lead to projection EPSG:4326.

2. Google maps can used with EPSG:4326, but data in EPSG:4326 will be
shifted.

3. transformation of coordinates in OpenLayers are only possible for
EPSG:4326 and EPSG:900913 or by adding proj4js to your application for other
projections, otherwise nothing happens.
   Your features are drawn in the given coordinates on a map with projection
EPSG:4326. Because EPSG:4326 and EPSG:4269 seems to be the same, your
features are in the view but will be shifted on the Google layer.

Create your map in EPSG:900913.

var options = {
    controls:[], //create map without controls -> add them later
    projection: new OpenLayers.Projection("EPSG:900913"),
    displayProjection: new OpenLayers.Projection("EPSG:4326"),
    units: "m",
    numZoomLevels: 18,
    maxResolution: 156543.0339,
    maxExtent: new OpenLayers.Bounds(-20037508, -20037508,
                                     20037508, 20037508.34)
};
var map = new OpenLayers.Map('TrackViewMap', options);

Set Google layer to sphericalMercator:true

Test the map without the use of proj4js by replacing EPSG:4269 with
EPSG:4326

Transform your points (from, to)
new OpenLayers.Geometry.Point("-80.2112656","44.3428574").transform(new
OpenLayers.Projection("EPSG:4326"),new OpenLayers.Projection("EPSG:900913"))

Add the layers

Add the controls
map.addControl(new OpenLayers.Control.LayerSwitcher());
map.addControl(new OpenLayers.Control.PanZoomBar());
map.addControl(new OpenLayers.Control.MouseDefaults());

Set your center and zoom
map.setCenter(new
OpenLayers.LonLat("-80.2112656","44.3428574").transform(new
OpenLayers.Projection("EPSG:4269"),new
OpenLayers.Projection("EPSG:900913")),0);
map.zoomTo(12);

And I hope, you will be pleased with the result.


Some hints:

your wms are added as baselayers, because they will added by default as
baselayers, when the param transparent is not set to true. isBaseLayer and
buffer are options.

var WMSLayer = new OpenLayers.Layer.WMS(title, url, {params}, {options});

var WMSLayer = new OpenLayers.Layer.WMS( 'Toporama Canada',
	["http://wms.ess-ws.nrcan.gc.ca/wms/toporama_en?"], {
	
layers:'hydrography,vegetation,road_network,feature_names,landforms',
	format:'image/png',
	transparent: true }, {isBaseLayer:true, buffer:0} );


You need only transform the features instead of all the points.

var mlsFeature = new OpenLayers.Feature.Vector(multiLineString.transform(new
OpenLayers.Projection("EPSG:4326"),new
OpenLayers.Projection("EPSG:900913")),null);

Regards,
Arnd 

-----Ursprüngliche Nachricht-----
Von: users-bounces at openlayers.org [mailto:users-bounces at openlayers.org] Im
Auftrag von Chris Garstin
Gesendet: Samstag, 22. August 2009 15:45
An: users at openlayers.org
Betreff: [OpenLayers-Users] WMS, Google Map, and Vector Layer


Hello there,

I know this has been discussed many times, so please bear with me, as I've
been spending hours trying to see how to fix my unique problem.

I have two WMS layers, and a Google layer in my map.  I also have an
overlay, which is just a multiLineString.  This overlay appears fine over
the WMS layers, but is shifted on the Google layer.  I know this has to do
with projections, but am really struggling with understanding how to fix it.

My attempts have included:

- Reprojecting the Google map.
- Reprojecting the WMS maps.
- Reprojecting the Vectory data on the fly.
- Creating a second Vector layer where the points are transformed.

None of these I am able to get to work, so an extra set of eyes would be
greatly apprecaited.

You can see my attempts at:

http://oo.chrisgarstin.com/maptrack.php?id=75

Regards
Chris
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