[GRASS-dev] Re: [GRASS GIS] #35: Verify and uncomment Swiss datum parameters

[GRASS GIS]

#35: Verify and uncomment Swiss datum parameters
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  Reporter:  neteler      |       Owner:  grass-dev at lists.osgeo.org
      Type:  defect       |      Status:  new                      
  Priority:  major        |   Milestone:  6.4.0                    
 Component:  default      |     Version:  unspecified              
Resolution:               |    Keywords:                           
  Platform:  Unspecified  |         Cpu:  Unspecified              
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Changes (by swisstopoum):

  * platform:  => Unspecified
  * cpu:  => Unspecified

Comment:

 CH1903 and CH1903+ are basically the same system (only defined a little
 bit differently). The problem is only the realisation of the system
 (CH1903/LV03 by triangulation ; CH1903+/LV95 by GPS). The differences
 between the 2 systems are in the order of 1.5 m in maximum.
 Today we don't recommend the use of the 7 parameter transform any more. So
 please - whenever possible - don't use them. For the transformation from
 CH1903+ to ETRS89 we use officially the following 3 parameters: dX=674.374
 m, dY=15.056 m; dZ=405.346 m.

 If necessary, you can model the differences between CH1903+ and CH1903
 with a distortion grid in the NTv2 format. This grid can be downloaded
 here:
 [http://www.swisstopo.admin.ch/internet/swisstopo/en/home/topics/survey/
 lv03-lv95/chenyx06/distortion_grids.html]

 More information on the Swiss system and projection can be found here:
 [http://www.swisstopo.admin.ch/internet/swisstopo/en/home/topics/survey/sys/refsys.parsysrelated1.2487.downloadList.78978.DownloadFile.tmp/swissprojectionen.pdf]

 In this document you find all the necessary formulas and parameters - as
 well as some examples.
 I revised this document in the meantime - but could not put it on the web
 yet. It contains some more explanations and more complete examples. Look
 for the revision date of the document: It should be 'october 2008'. If you
 need it right now, please contact me.
 Urs

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Ticket URL: <http://trac.osgeo.org/grass/ticket/35#comment:2>
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