[fusion-trac] #467: Display units as degrees shows incorrect x/y values in Fusion

[Fusion]

#467: Display units as degrees shows incorrect x/y values in Fusion
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   Reporter:  liuar   |       Owner:  madair  
       Type:  defect  |      Status:  assigned
   Priority:  P2      |   Milestone:  Future  
  Component:  Core    |     Version:  2.0     
   Severity:  Major   |    Keywords:          
External_id:          |       State:  New     
    Browser:  All     |          Os:  All     
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Changes (by madair):

  * status:  new => assigned


Comment:

 I think the core issue here is that the MapGuide WKT definition for
 WGS84.PseudoMercator in MapGuide is incorrect, at least it is not
 equivalent to the Google Spherical Mercator projection.

 To test, I'm checking the intersection of New Jersey Ave and River Park
 Road (aka S. 17th St):

  * in Google Maps, the coordinates of the intersection is (-87.7307,
 43.74652)
  * with Fusion, using default Sheboygan dataset in LL84, I get (-87.7307,
 43.7465)
  * modifying the MapGuide "WGS84.PseudoMercator" projection so that the
 datum is spherical I get (-87.7307, 43.7465)
  * using the MapGuide "WGS84.PseudoMercator" projection unchanged gives
 (-87.7307, 43.9387), ie. shifted north/south

 The WKT for the Google maps projection should be:

 PROJCS["Popular Visualisation CRS / Mercator",GEOGCS["Popular
 Visualisation CRS",DATUM["Popular_Visualisation_Datum",SPHEROID["Popular
 Visualisation
 Sphere",6378137,0,AUTHORITY["EPSG","7059"]],TOWGS84[0,0,0,0,0,0,0],AUTHORITY["EPSG","6055"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.01745329251994328,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4055"]],UNIT["metre",1,AUTHORITY["EPSG","9001"]],PROJECTION["Mercator_1SP"],PARAMETER["central_meridian",0],PARAMETER["scale_factor",1],PARAMETER["false_easting",0],PARAMETER["false_northing",0],AUTHORITY["EPSG","3785"],AXIS["X",EAST],AXIS["Y",NORTH]]

 Note the 0 as the second param of the spheroid which makes it a sphere.
 (this WKT also uses 'metre' as the unit rather than 'Meter' which causes
 other problems but that is another issue...)

 Net result of this is that I believe Proj4js and Fusion are doing the
 correct things, and by calculating the point on an ellipsoid rather than a
 sphere, MapGuide is shifting the map in North South.

 Comments please...

-- 
Ticket URL: <http://trac.osgeo.org/fusion/ticket/467#comment:1>
Fusion <http://trac.osgeo.org/fusion>
Fusion is a web-mapping application development framework for MapServer and MapGuide OS.