OSM layer in OpenLayers using EPSG:4326 overlays

[mdoyle]

Hi All,

We are using OpenLayers as the front end to our GIS app. I note that they have a handy Class OpenLayers.Layer.OSM, so we would like to utilise this.

One caveat: all of our other layers (base / overlays / data) are currently using projection EPSG:4326.

We would like to overlay these data grids over the top of OSM… I am aware OpenLayers can re-project and re-calculate x,y points on the fly, but when the underlying tiles are already in Spherical Mercator, then we’re forced to use this projection in all of our overlays right?

Does OSM offer tiles in other projections? Or will we have to ensure all of our data layers use Spherical Mercator when the OSM base layer is enabled?

Cheers,
Matt

[greencaps]

@mdoyle

…all of our other layers (base / overlays / data) are currently using projection EPSG:4326.

At http://wiki.openstreetmap.org/wiki/Openlayers_Track_example the example’s sourcecode (the javascript) at http://wiki.openstreetmap.org/wiki/OpenLayers_Simple_Example looks like:

new OpenLayers.Projection(“EPSG:4326”), // transform from WGS 1984
new OpenLayers.Projection(“EPSG:900913”) // to Spherical Mercator Projection

I’ve seen code like following too:

projection: new OpenLayers.Projection(“EPSG:900913”),
displayProjection: new OpenLayers.Projection(“EPSG:4326”)

So you can experiment a lot.