Another European Country Opens LiDAR: Welcome to the Party, Slovakia!

We got a little note from Vítězslav Moudrý from CULS pointing out that the Geodesy, Cartography and Cadastre Authority of the Slovak Republic has started releasing LiDAR as open data on their interactive Web portal. Congratulations, Slovakia!!! Welcome to the Open Data Party!!! We managed to download some data starting from this Web portal link and describe the process of obtaining LiDAR data from the Low Tatras mountain range in central Slovakia with pictures below.

open_data_portal_slovakia_01 — (1) click the new „data export“ link

open_data_portal_slovakia_02 — (2) change the export selection to „Shape“

open_data_portal_slovakia_03 — (3) change the file format to „LAZ“

open_data_portal_slovakia_04 — (4) zoom to a colored area-of-interest

open_data_portal_slovakia_05 — (5) zoom further and draw a nice polygon

open_data_portal_slovakia_06 — (6) edit polygon into nice shape and realize heart is red because area is too big

open_data_portal_slovakia_07 — (7) zoom further and draw polygon smaller than 2 square kilometer

open_data_portal_slovakia_08 — (8) when polygon turns green, accept license, enter email address and export

open_data_portal_slovakia_09 — (9) short wait and you get download link to such an archive

open_data_portal_slovakia_10 — (10) license conditions: PDF auto-translated from Slovak to English

open_data_portal_slovakia_11 — (11) LiDAR are spatially indexed flight lines clipped to area-of-interest

open_data_portal_slovakia_12_density_all_returns_20_50 — (12) **all** return density: blue = 20 and red = 50 returns per square meter

lasgrid -i LowTatras\*.laz -merged ^
        -step 2 -point_density_16bit ^
        -false -set_min_max 20 50 ^
        -o LowTatras\density_all_returns_20_50.png

open_data_portal_slovakia_13_density_last_returns_4_40 — (13) **last** return density: blue = 4 and red = 40 last returns per square meter

lasgrid -i LowTatras\*.laz -merged ^
        -keep_last ^
        -step 2 -point_density_16bit ^
        -false -set_min_max 4 40 ^
        -o LowTatras\density_last_returns_4_40.png

open_data_portal_slovakia_14_density_ground_returns_4_40 — (14) **ground** return density: blue = 4 and red = 40 ground returns per square meter

lasgrid -i LowTatras\*.laz -merged ^
        -keep_classification 2 ^
        -step 2 -point_density_16bit ^
        -false -set_min_max 4 40 ^
        -o LowTatras\density_ground_returns_4_40.png

open_data_portal_slovakia_14_overlap_10cm_20cm_diff — (15) flight line difference image: white <= +/- 10 cm and red/blue >= +/- 20 cm

lasoverlap -i LowTatras\*.laz -faf ^
           -drop_classification 7 18 ^
           -min_diff 0.1 -max_diff 0.2 ^
           -o LowTatras\overlap_10cm_20cm.png

Finally we compute a DSM and a corresponding DTM using the already existing ground classification with BLAST using the command sequence shown below.

lasthin -i LowTatras\*.laz -merged ^
        -drop_classification 7 18 ^
        -step 0.5 -highest ^
        -o LowTatras\highest_50cm.laz

blast2dem -i LowTatras\highest_50cm.laz ^
          -hillshade ^
          -o LowTatras -o dsm_1m_hillshaded.png

blast2dem -i LowTatras\*.laz -merged ^
          -keep_classification 2 ^
          -thin_with_grid 0.5 ^
          -hillshade ^
          -o LowTatras\dtm_1m_hillshaded.png

We thank the Geodesy, Cartography and Cadastre Authority of the Slovak Republic for providing their LiDAR as open data for both commercial and non-commercial purposes and name the source of the data used above (as the license requires) as the Office of Geodesy, Cartography and Cadastre of the Slovak Republic (GCCA SR) or – in Slovak – the Úrad geodézie, kartografie a katastra Slovenskej republiky (ÚGKK SR).

Which European country goes next? Czech Republic? Poland? Hungary? Switzerland?

Another European Country Opens LiDAR: Welcome to the Party, Slovakia!

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