[QGIS-trac] Re: [Quantum GIS] #3632: incorrect reprojection on windows (7), fine on linux

[Quantum GIS]

#3632: incorrect reprojection on windows (7), fine on linux
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   Reporter:  nirvn                                      |              Owner:  nobody       
       Type:  bug                                        |             Status:  new          
   Priority:  critical: causes crash or data corruption  |          Milestone:  Version 1.7.0
  Component:  Projection Support                         |            Version:  Trunk        
   Keywords:                                             |   Platform_version:               
   Platform:  Debian                                     |           Must_fix:  Yes          
Status_info:  0                                          |  
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Description changed by jef:

Old description:

> There's an on the fly reprojection issue going on with QGIS on windows
> platform (working fine under linux, untested on mac).
>
> On the windows version of QGIS, a WGS84 datum layer and its Indian 1960
> 48N datum equivalent fails to project on top of each other, ending up in
> a +450 meter (!) difference in location. (see screenshot attached)
>
> I've been noticing this for quite some time but didn't find a good way to
> explain the issue until now.
>
> Steps to reveal issue:
> 1/ Create a new program, set the CRS to UTM Indian 1960 48N and activate
> on the fly reprojection.
> 2/ Load the raster @ http://licadho-cambodia.org/qgis/ASTGTM_N11E103.zip
> (it's a simple aster gdem geotiff) into the project
> 3/ Using the gdal's wrap tool, transform the astgm_n11e103_dem.tiff's
> WGS84 datum to Indian 1960 48N datum
> 4/ Load the generated raster
> 5/ Apply the this colormap (http://licadho-cambodia.org/qgis/bugramp.txt)
> to both rasters to make it easier to observe the issue
>
> Et voila.
>
> Loading the two rasters into the linux version of QGIS will render just
> fine.

New description:

 There's an on the fly reprojection issue going on with QGIS on windows
 platform (working fine under linux, untested on mac).

 On the windows version of QGIS, a WGS84 datum layer and its Indian 1960
 48N datum equivalent fails to project on top of each other, ending up in a
 +450 meter (!) difference in location. (see screenshot attached)

 I've been noticing this for quite some time but didn't find a good way to
 explain the issue until now.

 Steps to reveal issue:
  1. Create a new program, set the CRS to UTM Indian 1960 48N and activate
 on the fly reprojection.
  1. Load the raster @ http://licadho-cambodia.org/qgis/ASTGTM_N11E103.zip
 (it's a simple aster gdem geotiff) into the project
  1. Using the gdal's wrap tool, transform the astgm_n11e103_dem.tiff's
 WGS84 datum to Indian 1960 48N datum
  1. Load the generated raster
  1. Apply the this colormap (http://licadho-cambodia.org/qgis/bugramp.txt)
 to both rasters to make it easier to observe the issue

 Et voila.

 Loading the two rasters into the linux version of QGIS will render just
 fine.

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Ticket URL: <https://trac.osgeo.org/qgis/ticket/3632#comment:1>
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