Sandro,
there is a NAD27 to WGS84 datum shift involved. So this might depend on
the transformations registered in the PROJ database of the version you
use and the grids available.
Result (-11708740.522541871, 3209723.515103944) is suboptimal as it is
the you get when no grids are used
Result (-11708734.486616733, 3209717.223316072) is the one using the
conus / us_noaa_conus.tif grid
Whether PROJ networking is enabled (PROJ_NETWORK=ON) can influence the
result (if it is set, then the conus grid will be used even if not
installed locally)
Even
Le 10/11/2021 à 00:02, Sandro Santilli a écrit :
I'm trying to obtain the *same* transformations from different
libproj versions (5.2.0 and 7.2.1) by passing the *same*
proj4 strings to the transformation, but I'm instead getting
different results.
In order to more easily test this I'm a small python script
using pyproj:
http://strk.kbt.io/tmp/transform_test.py
The script projects coordinates 0,0 from EPSG:32040
to EPSG:3857, using the proj4 string found in
PostGIS 3.1.4 spatial_ref_sys for those SRIDs.
On a machine (pyproj-3.2.1 using libproj-ce980207.so.22.1.1)
I'm getting these coordinates in output:
(-11708740.522541871, 3209723.515103944)
On another machine (pyproj-2.6.1 using libproj.so.19)
I'm getting these coordinates:
(-11708734.486616733, 3209717.223316072)
Can you think of a reason why I'd get different numbers ?
Would it be a regression for the libproj-ce980207.so.22.1.1
version to return different numbers ?
Please keep me in Cc in case of replies as I don't think I'm
receiving emails sent to this list.
--strk;
Libre GIS consultant/developer
https://strk.kbt.io/services.html
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My software is free, but my time generally not.
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