The DTM 1m, digital terrain model at 1m-resolution, is a homogeneous and regular point grid indicating the height of the ground level in order to model its surface, without taking into account objects on the surface such as buildings and vegetation. DTM 1m is achieved by interpolating in Lambert 2008 source data in Lambert 72 and at a 1m-resolution from the Flemish (2013-2015) and Brussels (2021) Regions, and by adding Lambert 2008 data at 1m-resolution from the Walloon Region (2021-2022).

The DTM 5m, digital terrain model at 5m-resolution, is a homogeneous and regular point grid indicating the height of the ground level in order to model its surface, without taking into account objects on the surface such as buildings and vegetation. The DTM 5m is the result of the assembly of different data coming from various sources and with different coordinate systems and resolutions. The DTM 1m is achieved by interpolating in Lambert 2008 source data in Lambert 72 and at a 1m-resolution from the Flemish (2013-2015) and Brussels (2021) regions, and by adding Lambert 2008 data at 1m-resolution from the Walloon Region (2021-2022). The DTM 5m is obtained by resampling of the DTM 1m. In addition, the DTM 5m is improved and updated internally using direct photogrammetric surveys based on the most recent aerial photographs.