1 Reply by atu

  • atu
  • Member
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  • From: Luxembourg
  • Registered: 06-10-2008
  • Posts: 26

Re: Precision of transforming from Gauss to LatLong

Hi,

What exactly is the precision of how recorder transform from gauss to latlong coordinates?

Example of Postgis transforming:

Gauss-x: 71017
Gauss-y: 70881

Long: 6.04247962438294
Lat: 49.5714694420217

Same Example of Recorder transforming:

Gauss-x: 71017
Gauss-y: 70881

Long: 6.04390509144542
Lat: 49.5726508560916

The latlong results differ from the third decimal place. Is this as it should be?
We use the Gauss-Luxembourg addin of recorder.

Thanks for replying,
Armand

atu's Website

2 Reply by SimonWood

  • SimonWood
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  • Registered: 09-09-2008
  • Posts: 63

Re: Precision of transforming from Gauss to LatLong

Hi Armand,

The algorithm used for Gauss-lux transformation is currently the one supplied by the Natural History Museum when the addin development was originally developered. There is a possibility that the transformation is not identical to PostGIS’s one, which is based on Proj4. Due to nature of co-ordinate transformations there does tends to be an inherent inaccuracy between different algorithms.

There is a generic XML Co-ordinate add-in that was developered for Germany that allows a configuration file to specify any transformation algorithm. Luxembourg Museum are currently testing the Add-in for use in Luxembourg.

Regards,

Sam

Simon Wood
[url=http://www.dorsetsoftware.com/]Dorset Software Services[/url]

SimonWood's Website