Forest in situ observations using unmanned aerial vehicle as an alternative of terrestrial measurements

Xinlian Liang, Yunsheng Wang*, Jiri Pyörälä, Matti Lehtomäki, Xiaowei Yu, Harri Kaartinen, Antero Kukko, Eija Honkavaara, Aimad E. I. Issaoui, Olli Nevalainen, Matti Vaaja, Juho-Pekka Virtanen, Masato Katoh, Songqiu Deng

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

82 Citations (Scopus)
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Background: Lately, terrestrial point clouds have drawn attention as a new data source for in situ forest investigations. So far, terrestrial laser scanning (TLS) has the highest data quality among all terrestrial point cloud data in terms of geometric accuracy and level of detail (IEEE Transact Geosci Remote Sens 53: 5117-5132, 2015). The TLS point clouds processed by automated algorithms can provide certain individual tree parameters at close to required accuracy in practical applications. However, all terrestrial point clouds face a general challenge, which is the occlusions of upper tree crowns. An emerging technology called unmanned-aerial-vehicle (UAV) - borne laser scanning (ULS) potentially combines the strengths of above and under canopy surveys.

Results: The performance of ULS are evaluated in 22 sample plots of various forest stand conditions in a boreal forest. The forest parameter estimates are benchmarked through a comparison with state-of-the-art terrestrial mechanisms from both static terrestrial and mobile laser scanning. The results show that in easy forest stand conditions, the performance of ULS point cloud is comparable with the terrestrial solutions.

Conclusions: This study gives the first strict evaluation of ULS in situ observations in varied forest conditions. The study also acts as a benchmarking of available active remote sensing techniques for forest in situ mensuration. The results indicate that the current off-the-shelf ULS has an excellent tree height/tops measurement performance. Although the geometrical accuracy of the ULS data, especially at the stem parts, does not yet reach the level of other terrestrial point clouds, the unbeatable high mobility and fast data acquisition make the ULS a very attractive option in forest investigations.

Original languageEnglish
Article number20
Number of pages16
JournalForest ecosystems
Issue number1
Publication statusPublished - 1 Dec 2019
MoE publication typeA1 Journal article-refereed


  • In situ
  • Point cloud
  • Terrestrial
  • Mobile
  • Above canopy
  • Unmanned aerial vehicle
  • Forest inventory


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