LiDAR guide · an IPR project
Where the data is
Mainland Portugal's LiDAR is distributed by the Direção-Geral do Território (DGT, the national mapping agency) through its Data Centre, with free registration. This page says what exists and where. The way to the files is learnt once, and quickly.
What exists
| Collection | What it is | Format |
|---|---|---|
| MDT-50cm | Digital terrain model, bare ground only, 50 cm pixel | GeoTIFF |
| MDT-2m | The same at 2 m (lighter) | GeoTIFF |
| MDS-50cm | Digital surface model, with trees and buildings, 50 cm | GeoTIFF |
| MDS-2m | The same at 2 m | GeoTIFF |
| LAZ | Classified point cloud | LAZ (LAS 1.4) |
(MDT and MDS are the Portuguese abbreviations for DTM and DSM.) For almost any land planning, the starting point is the DTM. The DSM shows canopies, hedges and buildings; the difference between the two gives vegetation height.
Where
In the DGT Data Centre. Data comes in 1 km tiles, with the collection, the tile code and the month and year of the flight in the file name. Each request has an area limit. When a tile is corrected, a new version appears (_v01, _v02): the latest one counts.
For large areas there is a community QGIS plugin, DGT CDD Downloader (qgispt, not a DGT product), which handles the requests and joins the tiles.
Before you ask
- What is the question? Water, tracks and planting need the DTM; canopies and buildings, the DSM; point classification, the LAZ.
- What resolution? At 50 cm, one square kilometre is 4 million pixels. A 500 ha farm fits on a laptop; a large catchment calls for the 2 m DTM, 16 times lighter.
- What margin? Water comes from beyond the property line. Ask for a margin of a few hundred metres.
To learn
DGT presented the survey in a public webinar (July 2025), with its specifications and coverage. There are also independent tutorials, such as GMT.jl's, listed in this page's sources. The rest is learnt by doing.