Package: gdal-bin
Version: 1.9.0-3.1
Severity: normal
Hi,
On stable Debian, with gdal-bin 1.9.0-3.1 and proj-bin 4.7.0-2, different
results are returned for the same co-ordinate transformations:
$ echo '-1.3893433684943819 52.7297093932173411' | cs2cs +init=epsg:4326 +to
+init=epsg:27700
441335.00 314849.00 -48.92
$ testepsg -t epsg:4326 epsg:27700 -1.3893433684943819 52.7297093932173411 0
(-1.389343,52.729709,0.000000) -> (441334.824686,314851.829623,-47.495477)
The results differ by a few metres. Looking at the internal definitions, we see
the following (testepsg comes from gdal-bin, cs2cs from proj-bin):
$ testepsg epsg:27700
...
+towgs84=375,-111,431,0,0,0,0 +units=m +no_defs
...
$ cs2cs -v +init=epsg:27700
...
# +towgs84=446.448,-125.157,542.060,0.1502,0.2470,0.8421,-20.4894
...
The "towgs84" parameters are different - a 7-parameter version with proj4, but
a 3-parameter version with GDAL. I would have assumed that both packages both
used the same underlying data (which I believe is libgeotiff) on the same
system, but I assume different versions of the data are bundled inside one or
both of these packages, leading to this issue. I tracked the libgeotiff change
down to
http://trac.osgeo.org/geotiff/changeset/2023/trunk/libgeotiff/csv/gcs.csv
- though I would have thought the 7-parameter version was more accurate (not
sure!)?
Anyway, I'm not sure if this has a solution, but it took long enough to track
down (PostgreSQL using proj4, Django using GDAL, so different results depending
where the transformation takes place) that I thought I'd open a report for it
in case anyone else came across the same issue.
ATB,
Matthew
-- System Information:
Debian Release: 7.6
APT prefers stable-updates
APT policy: (500, 'stable-updates'), (500, 'stable'), (50, 'testing')
Architecture: amd64 (x86_64)
Kernel: Linux 3.2.0-4-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash
Versions of packages gdal-bin depends on:
ii libarmadillo3 1:3.2.3+dfsg-1
ii libc6 2.13-38+deb7u4
ii libcurl3-gnutls 7.26.0-1+wheezy10
ii libdap11 3.11.1-11
ii libdapclient3 3.11.1-11
ii libdapserver7 3.11.1-11
ii libepsilon0 0.9.1-2
ii libexpat1 2.1.0-1+deb7u1
ii libfreexl1 1.0.0b-1
ii libgcc1 1:4.7.2-5
ii libgdal1 1.9.0-3.1
ii libgeos-c1 3.3.3-1.1
ii libgif4 4.1.6-10
ii libhdf4-0-alt 4.2r4-13
ii libhdf5-7 [libhdf5-7] 1.8.8-9+b1
ii libjasper1 1.900.1-13
ii libjpeg8 8d-1+deb7u1
ii libkml0 1.3.0~r863-4.1
ii liblzma5 5.1.1alpha+20120614-2
ii libmysqlclient18 5.5.38-0+wheezy1
ii libnetcdfc7 1:4.1.3-6+b1
ii libodbc1 2.2.14p2-5
ii libogdi3.2 3.2.0~beta2-7
ii libpng12-0 1.2.49-1
ii libpoppler19 0.18.4-6
ii libpq5 9.1.13-0wheezy1
ii libproj0 4.7.0-2
ii libspatialite3 3.0.0~beta20110817-3+deb7u1
ii libsqlite3-0 3.7.13-1+deb7u1
ii libstdc++6 4.7.2-5
ii liburiparser1 0.7.5-1
ii libxerces-c28 2.8.0+deb1-3
ii odbcinst1debian2 2.2.14p2-5
ii unixodbc 2.2.14p2-5
ii zlib1g 1:1.2.7.dfsg-13
gdal-bin recommends no packages.
Versions of packages gdal-bin suggests:
ii python-gdal 1.9.0-3.1
-- no debconf information
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