[OSRS-PROJ] commercial apps

Frank Warmerdam warmerdam at pobox.com
Wed Sep 19 13:20:42 EDT 2001

Paul Selormey wrote:
> Hello Frank,
> Can you or anyone give us more comparison between GeoTrans and Proj4?
> I alsofound GeoTrans easier, but with no support like for Proj4, I decided
> on Proj4.


I can't give a detailed comparison but these are a few things that stuck out
to me, though some of them could easily be wrong.

  o The code is more readable.  If you want to read code for individual
    projections to see how they are implemented, this is a good package.
  o Good integration with military identifiers for datums.
  o No simple textural format for describing coordinate systems.
  o No user level tools, just an API.
  o No active user group, though the package does appear to be actively
    maintained by someone within the military.

  o Code not all that useful for reference.
  o Has it's own unique list of datums, but recently has added good
    integration with EPSG (via EPSG init file) making coordinate system
    definition translation easier.
  o Simple, fairly well documented textual format for describing coordinate
  o user level tools (ie. proj.exe, cs2cs.exe) as well as API.
  o Active user group and "public" maintenance.

I have no experience with the comparitive accuracy of the two packages, though
Geotrans is apparently carefully audited for at least the things that matter
to the funding agency (NIMA?).

Note, there are a number of other worthwhile public projections
implementations.  I just listed geotrans before as an example because I
know the code is quite readable, and if you want to "adapt-your-own" it
might be a good base.

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

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