Jack Kirkpatrick wrote:
Greetings,
My apologies in advance if the following is stupid but I am not a GIS
expert (probably not even a GIS novice).
Some time ago I had call to transform corner coordinates from
"Australian Geodetic Datum 1966" to WGS84 so that I could accurately
drape some nautical charts in GeoTiff format onto Google Earth. I used a
utility called GEOTRANS2 which produced excellent mathematical results
but is decidely clunky to integrate.
I recently discovered the GDAL utilities and have been trying to
replicate this transformation without success.
----------------------------
I have netted down my efforts as follows:
(1) Environment is Windows XP SP3 and I have installed FWTools 2.2.9.
(2) I have a file [C:\fwtest\agd66.wkt] containing:
GEOGCS["AGD66",
DATUM["Australian_Geodetic_Datum_1966",
SPHEROID["Australian National Spheroid",6378160,298.249999999996,
AUTHORITY["EPSG","7003"]],
AUTHORITY["EPSG","6202"]],
PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433],
AUTHORITY["EPSG","4202"]]
Jack,
Your WKT file does not have any information on how to transform
from AGD66 to WGS84. Try using:
GEOGCS["AGD66",
DATUM["Australian_Geodetic_Datum_1966",
SPHEROID["Australian National Spheroid",6378160,298.249999999996,
AUTHORITY["EPSG","7003"],
TOWGS84[-133,-48,148]],
AUTHORITY["EPSG","6202"]],
PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433],
AUTHORITY["EPSG","4202"]]
I got the TOWGS84 values for AGD66 from the geotrans datum list which
is distributed in GDAL as gdal/data/gt_datum.csv.
Best regards,
--
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up | Frank Warmerdam, [email protected]
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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