[Proj] Datum conversion

pmarc paulomarcondes at gmail.com
Thu Jul 6 06:55:08 EDT 2006

2006/7/5, Hyer, Dr. Edward (Post Doc) <edward.hyer at nrlmry.navy.mil>:
> Hi,
> I am interested in doing point coordinate conversions from WGS84 lat/long points to SAD69. The SAD69 datum does not appear to be natively supported in proj or cs2cs. Can someone tell me where to find the parameters to use for this conversion?

Please be aware that there are at least two materializations of
SAD69... The original one, and one in '96 or '97.

Contact the Brazilian Survey guys at www.ibge.org for further details.

I've been using different parameters for wgs84/sad69 conversion,
following something I found on brazilian official docs.
+towgs84=-66.87,4.37,-38.52 (note that there is +/- 0.40m to  that
dimensions, according to the same doc.)

Otherwise they say the ellipsoids are identical.

cheers from Brazil
Paulo Marcondes = PU1/PU2PIX
-22.915 -42.229 = GG87vc (http://www.amsat.org/cgi-bin/gridconv)
Debian GNU/Linux = http://rj.debianbrasil.org = http://www.debian.org

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