[postgis-tickets] [PostGIS] #4712: Coordinate transformation from NAV4 to WGS84 is exact in Linux but in Windows it differs by 176 meters

[PostGIS]

#4712: Coordinate transformation from NAV4 to WGS84 is exact in Linux but in
Windows it differs by 176 meters
---------------------+---------------------------
 Reporter:  zellner  |      Owner:  pramsey
     Type:  defect   |     Status:  new
 Priority:  medium   |  Milestone:  PostGIS 3.0.2
Component:  postgis  |    Version:  3.0.x
 Keywords:           |
---------------------+---------------------------
 Comparing the results of coordinate transformation from NAV4 to WGS84 (and
 back) I receive different results when using a Postgresql database on
 Linux or Windows. The difference is in the used example about 176 meters.
 The Linux result seems to be ok compared to conversion in internet tools
 or in Oracle database. I used the following Postgresql and Postgis
 versions:

 SELECT version();
 \\
 -- Linux: PostgreSQL 12.2 on x86_64-pc-linux-gnu, compiled by gcc (GCC)
 8.3.1 20190507 (Red Hat 8.3.1-4), 64-bit
 \\
 -- Windows: PostgreSQL 12.1, compiled by Visual C++ build 1914, 64-bit

 SELECT postgis_full_version();
 \\
 -- Linux:   POSTGIS="3.0.1 ec2a9aa" [EXTENSION] PGSQL="120"
 GEOS="3.8.0-CAPI-1.13.1 " PROJ="6.3.1" LIBXML="2.9.7" LIBJSON="0.13.1"
 LIBPROTOBUF="1.3.0" WAGYU="0.4.3 (Internal)"
 \\
 -- Windows: POSTGIS="3.0.1 3.0.1" [EXTENSION] PGSQL="120"
 GEOS="3.8.0-CAPI-1.13.1 " PROJ="Rel. 5.2.0, September 15th, 2018"
 LIBXML="2.9.9" LIBJSON="0.12" LIBPROTOBUF="1.2.1" WAGYU="0.4.3 (Internal)"


 Block to be executed - as an example there are used the coordinates of a
 bus stop:

 DO $$\\
 DECLARE\\
   srIdFrom INTEGER := 31468; -- NAV4\\
   xFrom float := 4443865;\\
   yFrom float := 5506116;\\
   srIdTo INTEGER := 4326; -- WGS84\\
   point geometry;\\
 BEGIN
   RAISE NOTICE '-----------------------------------';\\
   point := ST_SetSRID(ST_Point(xFrom, yFrom),srIdFrom);\\
   RAISE NOTICE 'NAV4  POINT(% %)', ST_X(point)::text, ST_Y(point)::text;\\
   point := ST_Transform(point, srIdTo);\\
   RAISE NOTICE 'WGS84 POINT(% %)', ST_X(point)::text, ST_Y(point)::text;\\
   point := ST_Transform(ST_SetSRID(point,srIdTo), srIdFrom);\\
   RAISE NOTICE 'NAV4  POINT(% %)', ST_X(point)::text, ST_Y(point)::text;\\
 END;\\
 $$\\

 (You can also find the results in the attached Excel file I'll try to
 attach)

 Results:                      Longitude                    Latitude
 Diff Long (Oracle)        Diff Lat (Oracle)\\
 Oracle:                       11.2205674400711     49.6890969484351     0
 0\\
 Postgres (Linux):       11.220567440054587 49.68909694949477
 -1.66001E-11               1.0596E-09\\
 Postgres (Windows): 11.22192780146776   49.690197542586986 0.001360361
 0,00110059


 Differences (from Oracle):                Longitude [°]  Latitude [°]
 Diff Long [°]    Diff Lat [°]      Diff Long [m]   Diff Lat [m]    Diff
 Long/Lat [m] Lat. Factor      1° [m]\\
 Oracle                       11.22056744 49.68909695  0
 0                    0                     0                   0
 0.838438009 111111.111\\
 Postgres (Linux)       11.22056744 49.68909695  -1.66001E-11 1.0596E-09
 -1.54646E-06  0.00011773  0.000117743\\
 Postgres (Windows) 11.2219278   49.69019754  0.001360361  0.001100594
 126.7309668   122.288239 176.1111903

 The results within one database are consistent, so if I convert from NAV4
 to WGS84 and back again, then the original value is achieve very exactly
 (only rounding errors) also on a Windows system.

 Best regards
 Axel Zellner

-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/4712>
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