Izvorni znanstveni članak
Testing the Applicability of the Official Croatian DTM for Normalization of UAV-based DSMs and Plot-level Tree Height Estimations in Lowland Forests
Ivan Balenović
; Division for Forest Management and Forestry Economics Croatian Forest Research Institute Trnjanska cesta 35 Zagreb CROATIA
Luka Jurjević
; Division for Forest Management and Forestry Economics Croatian Forest Research Institute Trnjanska cesta 35 Zagreb CROATIA
Anita Simic Milas
; School of Earth, Environment and Society Bowling Green State University 190 Overman Hall Bowling Green, OH USA
Mateo Gašparović
; Chair of Photogrammetry and Remote Sensing Faculty of Geodesy, University of Zagreb Kačićeva 26 Zagreb CROATIA
Danijela Ivanković
; Division for Forest Management and Forestry Economics Croatian Forest Research Institute Trnjanska cesta 35 Zagreb CROATIA
Ante Seletković
; Department of Forest Inventory and Management Faculty of Forestry University of Zagreb Svetošimunska 25 Zagreb CROATIA
Sažetak
The Airborne Laser Scanning (ALS) technology has been implemented in operational forest inventories in a number of countries. At the same time, as a cost-effective alternative to ALS, Digital Aerial Photogrammetry (PHM), based on aerial images, has been widely used for the past 10 years. Recently, PHM based on Unmanned Aerial Vehicle (UAV) has attracted great attention as well. Compared to ALS, PHM is unable to penetrate the forest canopy and, ultimately, to derive an accurate Digital Terrain Model (DTM), which is necessary to normalize point clouds or Digital Surface Models (DSMs). Many countries worldwide, including Croatia, still rely on PHM, as they do not have complete DTM coverage by ALS (DTMALS). The aim of this study is to investigate if the official Croatian DTM generated from PHM (DTMPHM) can be used for data normalization of UAV-based Digital Surface Model (DSMUAV) and estimating plot-level mean tree height (HL) in lowland pedunculate oak forests. For that purpose, HL estimated from DSMUAV normalized with DTMPHM and with DTMALS were generated and compared as well as validated against field measurements. Additionally, elevation errors in DTMPHM were detected and eliminated, and the improvement by using corrected DTMPHM (DTMPHMc) was evaluated. Small, almost negligible variations in the results of the leave-oneout cross-validation were observed between HL estimated using proposed methods. Compared to field data, the relative root mean square error (RMSE%) values of HL estimated from DSMUAV normalized with DTMALS, DTMPHM, and DTMPHMc were 5.10%, 5.14%, and 5.16%, respectively. The results revealed that in the absence of DTMALS, the existing official Croatian DTM could be readily used in remote sensing based forest inventory of lowland forest areas. It can be noted that DTMPHMc did not improve the accuracy of HL estimates because the gross errors mainly occurred outside of the study plots. However, since the existence of the gross errors in Croatian DTMPHM has been confirmed by several studies, it is recommended to detect and eliminate them prior to using the DTMPHM in forest inventory.
Ključne riječi
Unmanned Aerial Vehicle; Digital Aerial Photogrammetry; Airborne Laser Scanning; Digital Surface Model; Digital Terrain Model; forest inventory
Hrčak ID:
217406
URI
Datum izdavanja:
14.1.2019.
Posjeta: 997 *