The key tasks of the National Land Survey of Finland (NLS) include aerial photography and laser scanning flights, which produce up-to-date information for the needs of society. Although the flights mostly succeeded well, the photography was partly spoiled by satellite positioning interference in southeastern Finland this year. Interference with satellite positioning (GNSS) has increased this year and, consequently, disruptions in access to reliable geospatial data.
In the opinion of the NLS, Finland needs a service that improves the safety of positioning by detecting interference in the air and at sea. The NLS has the required expertise to develop such a service based on its research focusing on positioning.
‘For the NLS and society at large to better prepare for the harm caused by GNSS interference, real-time situational awareness based on data is needed on land, at sea and in the air. The current situational awareness is based on reports made by users. The solution proposed by the NLS would involve a “weather advisory” for GNSS interference, which would provide an up-to-date picture of the quality and availability of the positioning signal. Such information about the current situation would be very useful, as it would also benefit air traffic,’ says Professor Sanna Kaasalainen, head of department from the Finnish Geospatial Research Institute FGI.
One of the statutory duties of the NLS is to secure the reliability of positioning data in Finland. The Finnish Transport and Communications Agency Traficom is responsible for monitoring the use of frequencies and investigating disturbances in Finland.
GNSS interference is already causing harm to society, and the risks are increasing
Aerial photography and laser scanning materials produced by the NLS are critical to many functions of society. Among others, the information is used by the Finnish Defence Forces, the Finnish Food Authority, and various operators in the nature and forest sectors.
The financial benefits of the laser scanning and aerial photography data for the forest sector and in avoiding flood damage amount to tens of millions of euros annually. If the data collection fails, it will have consequences for numerous users of the data.
For example, the lack of laser scanning data from the Kouvola region means that the Finnish Forest Centre will be unable to carry out the collection of forest resource data in the area as planned, which will become costly to forestry. At the same time, deficiencies in aerial photography data will cause problems in the control of the EU’s agricultural subsidies. Particularly when prolonged, GNSS interference and problems with data collection will thus cause significant costs to society as a whole.
Despite the challenges, the photography season was completed – the aerial photographs will be available as open data
Between April and August, the NLS and its subcontractors photographed about a third of Finland’s surface area from the air, and laser scanned about a sixth. Aerial photography was carried out in various locations during the season, including Salla, Kokkola, Vaasa and Savonlinna. Laser scanning data was collected this season from Ivalo, Varkaus and Jämsä, among other areas.
‘The weather was favourable, and we were able to take aerial photos and laser scans of almost all the planned areas, including the areas left in the backlog from last year,’ says Juha Kareinen, head of cartography at the NLS.
The status map service shows the areas that were covered by aerial photography and laser scanning this year. In addition, the service shows the areas to be photographed and scanned in the national laser scanning and aerial photography programmes in the coming years.
Fresh aerial photographs from this summer can already be found in all the NLS services. The last aerial photographs will be published by the end of October. The aerial photographs are available as open data. The laser scanning materials will be finalised during the autumn, and the data for the last areas will be available by the end of November.
A lower-density version of the laser scanning materials is available as open data. The material in the original point density is public, but requires approval of the licence and user identification.
Learn more about obtaining laser scanning data.
Further information
About interference with satellite positioning:
Professor Sanna Kaasalainen, Head of the Department of Navigation and Positioning at the Finnish Geospatial Research Institute, +358 29 531 4760
About aerial photography and laser scanning:
Juha Kareinen, Head of Cartography, +358 40 569 7951
The email format is firstname.lastname@nls.fi