Conversion from Belgian 72 to Lambert 2008 (ETRS89)

The Belgian Lambert 2008 projection system (EPSG:3812) is based on the ETRS89 geodetic system. It integrates better across borders. It is now established as a reference in accordance with the INSPIRE directive.

The Belgian National Geographical Institute provides to users on its website an NTv2 grid for the transformation of geographical data expressed in the Datum Belge72 to the ETRS89 Datum.

This transformation grid has been integrated by ESRI with their new version of ArcGIS software.

Given the amount of data needed for the transformation grids available for different countries, these transformations are contained in a module to download and install separately.

This module is called “ArcGIS Coordinate Systems Data”.

To find it, go to My Esri in the download group for ArcGIS Pro related modules. If this is not the case, view the details of each group of modules (“Expand / Collapse All”), and go to the “Data and Content” group. The “ArcGIS Coordinate System Data” module is to be downloaded from here.

This module installs like any other module in ArcGIS Pro.

If you do not need all transformations, you can choose to install part of the contents of this module (for example the transformation of Datum “Vertical World 1×1” which occupies 890 MB of disk space) by clicking on the icon next to the specific component:

After installation, the NTv2 transformation from Datum Belge72 to Datum ETRS89 is available under the name “Belge_1972_To_ETRS_1989_3”.

Below an example in ArcGIS Pro:

You need to consider the installation type of ArcGIS Pro (determined by the installation settings, see https://pro.arcgis.com/pro-app/get-started/arcgis-pro-installation- administration.htm).

If it’s a “per user” installation (this is the default installation option, parameter ALLUSERS = 2), you will need to install the “ArcGIS Coordinate Systems Data for ArcGIS Pro Per User Install” module.

If it’s a “per machine” installation (parameter ALLUSERS = 1), the “ArcGIS Coordinate Systems Data” module must be installed.