[gdal-dev] gdaltransform user problems

[Jack Kirkpatrick]

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"]]
 
(3) I have a file [C:\fwtest\wgs84.wkt] containing:

GEOGCS["WGS 84",
DATUM["WGS_1984",
SPHEROID["WGS 84",6378137,298.2572235630016,
AUTHORITY["EPSG","7030"]],
AUTHORITY["EPSG","6326"]],
PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433],
AUTHORITY["EPSG","4326"]]

(4) I have a file [C:\fwtest\agd66 point.txt] containing a point in AGD66

-151.1025110 -33.7738883

(5) I have a file [C:\Program Files\FWTools2.2.9\fwtest.bat] containing a single line:

gdaltransform -s_srs "c:\fwtest\agd66.wkt" -t_srs "c:\fwtest\wgs84.wkt" < "c:\fwtest\agd66 point.txt" > "c:\fwtest\wgs84 point.txt"

(6) I launch the FWTools shell via the [FWTools Shell] shortcut on the desktop and within the FWTools shell I key:

fwtest

(7) I inspect the resulting file [C:\fwtest\wgs84 point.txt] which shows:

-151.102511 -33.7738883 0

i.e. no transformation has occurred, with GEOTRANS2 I would have expected a result like:

-151.103659 -33.7723069 0

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I have tried numerous permutations, including using [-s_srs EPSG:4202 -t_srs EPSG:4326] instead of the *.wkt files (same result) and inserting garbage into the *.wkt files to see if gdaltransform is actually reading them (which it seems to be doing).

I have spent some considerable number of hours on this to no avail so time to run up the white flag - any and all comments appreciated.
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