[QGIS-trac] Re: [Quantum GIS] #1176: Transverse mercator south orientated projections not supported

[Quantum GIS]

#1176: Transverse mercator south orientated projections not supported
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        Reporter:  halfhaggis                        |         Owner:  homann       
            Type:  bug                               |        Status:  new          
        Priority:  major: does not work as expected  |     Milestone:  Version 1.0.1
       Component:  Projection Support                |       Version:  HEAD         
      Resolution:                                    |      Keywords:               
Platform_version:                                    |      Platform:  Debian       
        Must_fix:  Yes                               |   Status_info:  0            
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Changes (by gfleming):

  * priority:  minor: annoyance or enhancement => major: does not work as
               expected
  * must_fix:  No => Yes

Comment:

 See also [http://trac.osgeo.org/proj/ticket/18 proj4 ticket #18] and
 [http://code.google.com/p/postgis/issues/detail?id=61&can=4 PostGIS ticket
 61]

 I'm not sure -m is the approach - we're not trying to switch coordinate
 signs here.

 The Hartebeesthoek datum references the WGS84 ellipsoid. There is no
 transformation between them so they can be used interchangeably in
 practice - they differ in name only, but Hartebeesthoek is the South
 African standard and has been since 1999.

 Interest only: The old datum, which still applies to much data, is the
 Cape datum (Clarke 1880 MODIFIED). There is no accurate direct
 transformation between Cape and Hartebeesthoek - instead a localised,
 controlpoint-based transformation needs to be applied.

 See http://w3sli.wcape.gov.za/SURVEYS/MAPPING/wgs84.htm for details about
 the Hartebeesthoek datum.

 From my other tickets:

 South African Coordinate System zone xx (EPSG odd numbers from 22275 -
 22293)

 and

 Hartebeesthoek94/ Loxx (EPSG 2046 - 2055)

 are not supported / do not have standard definitions in proj4. South
 Africa users of proj4, QGIS, PostGIS and others are thus crippled.

 Attached are the WKT and PROJ4 definitions as csv’s from PostGIS
 spatial_ref_sys.

 SA Hartebeesthoek datum.csv:

 4148 is fine - that's the fundamental GEOGCS. The rest have default,
 invalid proj4 definitions, except for 2054 (the last one) where I have
 attempted a proj4 definition but I don’t think it’s quite right - it
 doesn't work.

 SA Cape datum.csv:

 The proj4 definitions for the SA Cape datum projections are INCOMPLETE.
 They only include the datum specs, not the projection or central meridian
 or other parameters.

-- 
Ticket URL: <https://trac.osgeo.org/qgis/ticket/1176#comment:7>
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