Datum conversion

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Datum conversion

Hyer, Dr. Edward (Post Doc)
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?

Thanks for your help,

Dr. Edward J. Hyer
Post-Doctoral Researcher
Naval Research Laboratory
Marine Meteorology Division
7 Grace Hopper Avenue, Stop 2
Monterey, California 93940
831-656-4023
FAX 831-656-4769
[hidden email]

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Re: Datum conversion

Clifford J Mugnier




Look in TR 8350.2 at:

http://earth-info.nga.mil/GandG/publications/

Note that this information is considered obsolete for operational use.  For
further information, contact the good folks at the Arnold, MO office of
NGA.

Note that South America is now on SIRGAS and not SAD69.  SAD69 was "thunk
up" by Dr. Irene Fischer, a very nice lady.  She's in her 80s or 90s now,
is about 4'10", and I once watched her chew out a three-star Admiral during
a classified symposium at Cameron Station some 38+ years ago!

Good luck,

Clifford J. Mugnier, C.P., C.M.S.
National Director (2006-2008),
Photogrammetric Applications Division
American Society for Photogrammetry and Remote Sensing
and
Chief of Geodesy,
CENTER FOR GEOINFORMATICS
Department of Civil Engineering
CEBA 3223A
LOUISIANA STATE UNIVERSITY
Baton Rouge, LA  70803
Voice and Facsimile:  (225) 578-8536 [Academic]
Voice and Facsimile:  (225) 578-4474 [Research]
Honorary Life Member of the
Louisiana Society of Professional Surveyors
======================================================
http://www.asprs.org/resources/GRIDS/
http://appl003.lsu.edu/eng/ceeweb.nsf/$Content/Mugnier
======================================================



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?

Thanks for your help,

Dr. Edward J. Hyer
Post-Doctoral Researcher
Naval Research Laboratory
Marine Meteorology Division
7 Grace Hopper Avenue, Stop 2
Monterey, California 93940
831-656-4023
FAX 831-656-4769
[hidden email]

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Proj mailing list
[hidden email]
http://lists.maptools.org/mailman/listinfo/proj

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Re: Datum conversion

Anthony Dunk
In reply to this post by Hyer, Dr. Edward (Post Doc)
The SAD69 datum is not directly supported so you just have to provide
the ellipsoid parameters and the "towgs84" conversion values.

The following command will convert from lat/lon WGS74 to lat/lon SAD69:

cs2cs +proj=latlong +datum=WGS84 +to +proj=latlong +a=6378160.0
+rf=298.25 +towgs84=-57,1.0,-41

Anthony


--- "Hyer, Dr. Edward (Post Doc)" <[hidden email]> wrote:

> 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?
>
> Thanks for your help,
>
> Dr. Edward J. Hyer
> Post-Doctoral Researcher
> Naval Research Laboratory
> Marine Meteorology Division
> 7 Grace Hopper Avenue, Stop 2
> Monterey, California 93940
> 831-656-4023
> FAX 831-656-4769
> [hidden email]
>
> _______________________________________________
> Proj mailing list
> [hidden email]
> http://lists.maptools.org/mailman/listinfo/proj
>




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Re: Datum conversion

Paulo Marcondes
In reply to this post by Hyer, Dr. Edward (Post Doc)
2006/7/5, Hyer, Dr. Edward (Post Doc) <[hidden email]>:
> 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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