[OpenMap Users] meters -> latlon

From: Tore Halset <halset_at_pvv.ntnu.no>
Date: Mon, 26 Feb 2007 12:44:38 +0100


I am working on a project to use OpenMap as a WMS server. It is
working very well, but it does currently only support SRS=EPSG:4326
(unprojected). I want to support OSGEO:41001[1] (Mercator) as well.

The problem with OSGEO:41001and a lot of other SRSs used in the OGC
WMS/WFS world is that the units are in meters instead of in degrees
lat/lon. To match OpenMap projection system (based on lat/lon) I
guess I will need a frontend that convert all incoming meters to
degrees before handling over to OpenMap projection.

I know of Length.METER and have used it to find distances, but I do
not know how to use it or anything else to convert incoming x/y in
meters to lat/lon. Perhaps I can use Length.METER to convert the
direct distance between the projection origin and the point and then
the same for delta lat. Using it for delta lon will not work (as the
world is not flat), but Pythagoras should help me find this last number.

Am I thinking correct here? Anyone done this before in OpenMap and
want to give me some hints?

  - Tore.
[1] http://wiki.osgeo.org/index.php/WMS_Tiling_Client_Recommendation

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Received on Mon Feb 26 2007 - 06:49:32 EST

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