[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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Comment (by swisstopoum):

 Replying to [comment:3 msieczka]:
 >
 > Strange. Is 3 parameter transformation more accurate than the 7 one?
 >
 Answer: A 7-parameter transformation is always more accurate than a
 3-parameter solution. But in the case of Switzerland it really does not
 improve the situtation significantly. The residuals remain in the order of
 1.5 meters if you apply the 7-parameter transform. So, it only would
 complicate the calculation (sign and units of the rotations) without too
 many benfits. If you want to go near the 1cm-level, the NTv2 grid (or any
 other method of modelling local distortions) is the right approach.

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Ticket URL: <http://trac.osgeo.org/grass/ticket/35#comment:5>
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