[mapguide-internals] RE: EPSG:3785 or with CS-Map?

[Hugues Wisniewski]

We just added this item to the CsMap maintenance list. There's no ETA concerning when this will be done though.
It's a matter of adding new definitions to the dictionaries and updating the csv mapper file.

>From Norm Olsen's input:

"The essence is here:

DATUM["Popular_Visualisation_Datum",
                SPHEROID["Popular Visualisation Sphere",6378137,0,AUTHORITY["EPSG","7059"]],
                TOWGS84[0,0,0,0,0,0,0],AUTHORITY["EPSG","6055"]
                ]

1> The SPHEROID is a sphere with the radius equal to the equatorial radius of WGS84 (and GRS80, they are the same).  Can be added to the ellipsoid dictionary. They gave it the name "Popular Visualisation Sphere".
2> The Datum is essentially WGS84, but not referenced to the WGS84 ellipsoid. A new datum definition could be defined which would reference this new ellipsoid. I believe it important to set the USE: specification to WGS84, so none of the standard datum code which deals with eccentricity (zero in this case) is executed.
We'll also want to add these specific names to the NameMapper table"

Hugues


-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org [mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Bruce Dechant
Sent: Wednesday, April 01, 2009 1:28 PM
To: MapGuide Internals Mail List
Subject: [mapguide-internals] RE: EPSG:3785 or with CS-Map?

How would one go about adding this EPSG code as a supported system?

Thanks,
Bruce

________________________________________
From: mapguide-internals-bounces at lists.osgeo.org [mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Hugues Wisniewski
Sent: Wednesday, April 01, 2009 2:25 PM
To: MapGuide Internals Mail List
Subject: [mapguide-internals] RE: EPSG:3785 or  with CS-Map?

Hi again,

Let me rephrase that one a bit.

CsMap doesn't have a system in its dictionaries for this EPSG code but if the WKT is provided to the API in input, a custom system will be created.

Since MapGuide understands such systems and doesn't need to have a system physically present in its dictionary to be able to work, MapGuide can work with this WKT.

If instead of the WKT expression the EPSG code is used to initialize the underlying MgCoordinateSystem API, the initialization will fail.

Hugues


-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org [mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Hugues Wisniewski
Sent: Wednesday, April 01, 2009 12:29 PM
To: MapGuide Internals Mail List
Subject: [mapguide-internals] RE: EPSG:3785 or with CS-Map?

Hi Jason,

This system is currently not supported by CsMap

Hugues


-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org [mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Jason Birch
Sent: Wednesday, April 01, 2009 11:56 AM
To: 'MapGuide Internals Mail List'
Subject: [mapguide-internals] EPSG:3785 or with CS-Map?

Brian asked a question about using the "Google Maps Projection" with MapGuide.  I was hoping that CS-Map would support EPSG:3785 natively, but I can't get it to work with the latest 2.1 installer using any of the CS web tier test pages.  Here's the definition:

http://spatial-reference.org/ref/epsg/3785/ogcwkt/

Is there a projection code for this?  Do I need to add some kind of lookup?  Because Fusion 2.0 supports multiple map layers, I'd imagine that many users will want to have a Google Maps base layer.  Ideally, we could bundle this CS definition to help these users.

Thanks,
Jason
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