Single-Scan TLS Methods for Forest Parameter Retrieval

Using a terrestrial laser scanner (TLS) in single-scan mode for achieving plot level reference data in forests is proposed in this paper. In single-scan operation the amount of data is small compared to multi-scan and the registration of different scans is not needed, thus both the measurement and the processing are faster and fully automatic. The scan geometry was utilized in the development of the processing method. The forest scene complexity and that some trees are totally shadowed by the others are the main limiting factors to the use of single-scan TLS. We expect our methods to operate well at least on single layer, pine dominated economically exploited boreal forests. The main result of the TLS based forest parameter method is the location and stem curve for each tree that was detected. In traditional forest ground truth reference measurements, each tree is manually measured in the reference plot and the tree location is not recorded. The possibility to record the location of major trees by TLS makes the plot information usage more practical: corrections can be done, they can be used as permanent plots, they serve as a basis of future individual tree based forest inventory. In our test area, 85% of the 52 trees that were manually found from the TLS data slice inside 60m range could b