2nd project cycle (2022 – 2026) and creation of DTM 6.0

Basic specification of the project

The whole territory of the Slovak Republic is divided into 73 lots:

 
The ALS takes place gradually by individual lots from the west of Slovakia to the east. The awarding of contracts for the ALS and the implementation of works at the individual lots is carried out by successive re-opening of tenders between the 4 participants of the framework agreement, which are:
- Eurosense spol. s r.o., 
- Photomap spol. s r.o.,
- PRIMIS spol. s r.o.,
- MGGP Aero Sp. z o.o.

The subject of the contract is:
- data collection by airborne laser scanning,
- processing of point clouds and delivery of classified point clouds*,
- quality control of point clouds. 

*Compulsory classification into 10 classes - 01 Unclassified, 02 Ground, 03 Low vegetation, 04 Medium vegetation, 05 High vegetation, 06 Building, 07 Low point (Noise), 09 Water, 17 Bridge deck and 18 Hight Noise.
Optional classification into 12 classes - 01 Unclassified, 02 Ground, 03 Low vegetation, 04 Medium vegetation, 05 High vegetation, 06 Building, 07 Low point (Noise), 09 Water, 17 Bridge deck, 18 Hight Noise, 14 Power lines (Wire) and 15 Tower.

Note: As the successful tenderers' bids are evaluated on the basis of the most economically advantageous tender criterion, the suppliers have the possibility to offer qualitatively higher parameters than the mandatory criteria. For this reason, the subject of the contract may vary from lot to lot.

Compulsory quality criteria:
- scanning density: min. 15 points per m²,
- overlap between swaths min. 40% on 95% of their mutual coincidence,
- horizontal and vertical system:ETRS89-TM34+h_ETRS89,
- abs. vertical accuracy of point clouds at ellipsoidal heights ETRS89 - m_h ≤ 0,10 m,
- abs. positional accuracy of point clouds in ETRS89-TM34 – m_XY ≤ 0,20 m,

The ALS is carried out at individual lots mainly in winter vegetation-free period from October (November) to April. The result of laser scanning is so-called 'point clouds', which correspond to the Earth's surface from which the laser pulse is reflected.

Quality control:
The quality control is carried out independently by the contractor and ÚGKK SR. The contractor demonstrates by the results of its own control that all the specified conditions and quality parameters are met. ÚGKK SR, in cooperation with GKÚ Bratislava and VÚGK, carry out the control to independently verify the fulfilment of the contractual requirements. Only on the basis of the successful results of both controls does ÚGKK SR accept the work.

The subject of the controls is mainly:
- scanning density (last reflection points),
- overlaps of adjacent swaths,
- relative vertical and horizontal accuracy,
- correctness of point classification into defined classes**,
- absolute horizontal and vertical accuracy of point clouds,
- absolute vertical accuracy of DTM.

**In the Ground class, a maximum of 0,5% occurrence of misclassified points per 1 km² of territory is allowed. In other classes (except Unclassified) a maximum of 5% of misclassified points per 1 km² of territory is allowed.

An absolute horizontal and vertical accuracy control of point clouds is carried out at geodetically surveyed vertical and horizontal control points (using SKPOS), located on open paved areas at several randomly selected locations within each lot.

Further specifications and actual quality parameter values achieved by the contractors for individual lots are given in the metadata of the respective dataset and in the table HERE.

Information about the provision of ALS products from the 2^nd cycle is here.