Airborne Laser Scanning and DTM 5.0

A project for creating a new Digital Terrain Model (DTM 5.0) for the whole territory of Slovakia was launched in 2017 by the Geodesy, Cartography and Cadastre Authority of the Slovak Republic (ÚGKK SR). It is a 6 year-long activity where the new DTM 5.0 will be created from the data of airborne laser scanning (ALS). The laser scanning and following post-processing of data is carried out by private segment. The whole territory of the Slovak Republic is divided into 42 localities (lots). Individual lots are scanned separately and the process of laser scanning goes from the west of the country to the east.

Project outcomes:
   -   collection of data by airborne laser scanning,
   -   processing of point cloud and delivering Classified Point Cloud,
   -   Digital Terrain Model DTM 5.0 in raster form,
   -   Digital Surface Model DSM 1.0 in raster form,
   -   quality control of point cloud and DTM.

Mandatory quality criteria:
    -   scanning density is at least 5 points per m²,
    -   lots with 250 m swath on 95% of their overlap,
    -   horizontal and vertical system: S-JTSK(JTSK03)+H_Bpv; ETRS89-TM34+h_ETRS89,
    -   absolute vertical accuracy of point cloud at ellipsoidal heights ETRS89 - m_h ≤ 0.15 m,
    -   absolute positional accuracy of point cloud in ETRS89-TM34 - m_XY ≤ 0.30 m,
    -   absolute vertical accuracy of DTM 5.0 in h_ETRS89 - m_H ≤ 0.20 m,
    -   absolute vertical accuracy of DTM 5.0 in Bpv – m_H ≤ 0,25 m,

Quality control:
The control of absolute horizontal and vertical accuracy is performed at geodetically surveyed checkpoints located on open paved areas at several randomly selected locations within each lot. The quality control is independently performed by the supplier and the Geodesy, Cartography and Cadastre Authority of the Slovak Republic.

Finished lots available for use are highlighted in green in the picture below. Due to the large volume of data (several TB) the data is provided only in offline mode by individual lots in their entirety. Users must bring or send an external HDD (USB 3.1 is recommended) to download the data. Please note that because of the large amount of data and time involved, the copying of data is not done while you wait. Data collection points are offices in Bratislava (Chlumeckého 4) and Prešov (Suvorovova 2). Smaller volume data (sections) can be downloaded via the Map Client ZBGIS application, more information here. User is obliged to state the source of the ALS Products while creating his/her own work and when publishing it as follows: „ÚGKK SR“.

• Overview of lots in Shapefile format
• Overview of parameters of available lots 
• Overview of LAS file footprints
• How to work with DTM in QGIS application (Slovak only)
• How to work with point cloud in QGIS application (Slovak only)
• How to unpack LAZ format to LAS format using LASzip (Slovak only)

If you are interested in obtaining Classified Point Cloud, Digital Terrain Model 5.0 (DTM 5.0) or Digital Surface Model (DSM 1.0), please complete the order form and deliver it to the contact address here:

• Order form for Classified Point Cloud
• Order form for DTM 5.0
• Order form for DSM 1.0

The provided Products are subject to the Terms and Conditions of the Provision and Use of Airborne Laser Scanning Products.

Table of approximate ALS product file sizes is available for download  here.