Since ArcGIS Pro 2.2 and QGIS 3.2 arrived recently, it was time to have again a look if and how the AT_GIS_GRID for CRS-transformation between Austrian BMN (Bundesmeldenetz) and ETRS89 (and WGS84) is implemented. The easy question: Does EPSG::5891 (AT_GIS_GRID NTv2 transformation) work out of the box ?
The transformation task: From Austrian BMN (M28 M31 M34) to ETRS89 (EPSG:4258) with the most accuracy using NTv2 with AT_GIS_GRID (EPSG:5891; +/- 0,5m). More on the topic in this earlier article http://isticktoit.net/?p=371
ArcGIS Pro 2.2
Good news ! The NTv2 transformation using AT_GIS_GRID is integrated out-of-the-box including the gsb-File 🙂
But let’s have a detailed look:
- The transformation options in AG Pro display some cryptic methods without any EPSG-Code or „name“… but „…ETRS89_5“ is what we are looking for 🙂 So, nice work by ESRI – it would be nice if the transformation-methods would include the EPSG-Code.
- Where do we find what „…ETRS89_5“ is ? ESRI delivers a pdf with the installation – just search for geographic_transformations.pdf in the installation-directory.
- The AT_GIS_GRID gdb-File is delivered with ArcGIS Pro as well
QGIS supports NTV2-transformations, but AT_GIS_GRID is not integrated, nor the necessary gsb-File. So some manual work has to be done…
- Get the AT_GIS_GRID gsb-File from BEV (www.bev.gv.at)
- Add the transformation to the projections-&transformations database (srs.db)
The result: We are able to choose AT_GIS_GRID as transformation method
The 2 steps in detail:
Step 1 : Get AT_GIS_GRID gsb-File from www.bev.gv.at and copy it in the correspondent directory:
- gsb-Files Linux: /usr/share/proj/
- gsb-Files Windows: C:\Program Files\QGIS 3.2\share\proj
Step 2: Modify the srs.db file (database) with a SQLite database editor and add the necessary entry for AT_GIS_GRID in table „tbl_datum_transform“
- srs.db Linux: /usr/share/qgis/resources
- srs.db Windows: C:\Program Files\QGIS 3.2\apps\qgis\resources
Add the following entry:
After manually integrating AT_GIS_GRID the option of choosing it should be in QGIS 3.2
AT_GIS_GRID works fine with both products – and well done ESRI for delivering it out of the box.