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Evaluating the performance of multi-rotor UAV-Sfm imagery in assessing simple and complex forest structures: comparison to advanced remote sensing sensors
The implementation of Unmanned Aerial Vehicles (UAVs) and Structure‐from‐Motion (SfM) photogrammetry in assessing forest structures for forest inventory and biomass estimations has shown great promise in reducing costs and labour intensity while providing relative accuracy. Tree Heigh...
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| Format: | Thesis |
| Language: | English |
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School of Architecture, Planning and Geomatics
2022
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| _version_ | 1867613249787133952 |
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| access_status_str | Open Access |
| author | Onwudinjo, Kenechukwu Chukwudubem |
| author2 | Smit, Julian |
| author_browse | Onwudinjo, Kenechukwu Chukwudubem Smit, Julian |
| author_facet | Smit, Julian Onwudinjo, Kenechukwu Chukwudubem |
| author_sort | Onwudinjo, Kenechukwu Chukwudubem |
| collection | Thesis |
| description | The implementation of Unmanned Aerial Vehicles (UAVs) and Structure‐from‐Motion (SfM) photogrammetry in assessing forest structures for forest inventory and biomass estimations has shown great promise in reducing costs and labour intensity while providing relative accuracy. Tree Height (TH) and Diameter at Breast Height (DBH) are two major variables in biomass assessment. UAV-based TH estimations depend on reliable Digital Terrain Models (DTMs), while UAV-based DBH estimations depend on reliable dense photogrammetric point cloud. The main aim of this study was to evaluate the performance of multirotor UAV photogrammetric point cloud in estimating homogeneous and heterogeneous forest structures, and their comparison to more accurate LiDAR data obtained from Aerial Laser Scanners (ALS), Terrestrial Laser Scanners (TLS), and more conventional means like manual field measurements. TH was assessed using UAVSfM and LiDAR point cloud derived DTMs, while DBH was assessed by comparing UAVSfM photogrammetric point cloud to LiDAR point cloud, as well as to manual measurements. The results obtained in the study indicated that there was a high correlation between UAVSfM TH and ALSLiDAR TH (R2 = 0.9258) for homogeneous forest structures, while a lower correlation between UAVSfM TH and TLSLiDAR TH (R2 = 0.8614) and UAVSfM TH and ALSLiDAR TH (R2 = 0.8850) was achieved for heterogeneous forest structures. A moderate correlation was obtained between UAVSfM DBH and field measurements (R2 = 0.5955) for homogenous forest structures, as well as between UAVSfM DBH and TLSLiDAR DBH (R2 = 0.5237), but a low correlation between UAVSfM DBH and UAVLiDAR DBH (R2 = 0.1114). This research has demonstrated that UAVSfM can be adequately used as a cheaper alternative in forestry management compared to more highcost and accurate LiDAR, as well as traditional technologies, depending on accuracy requirements. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/35996 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:33:08.525Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2022 |
| publishDateRange | 2022 |
| publishDateSort | 2022 |
| publisher | School of Architecture, Planning and Geomatics |
| publisherStr | School of Architecture, Planning and Geomatics |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/35996 Evaluating the performance of multi-rotor UAV-Sfm imagery in assessing simple and complex forest structures: comparison to advanced remote sensing sensors Onwudinjo, Kenechukwu Chukwudubem Smit, Julian Unmanned Aerial Vehicles Structure‐from-Motion Aerial Laser Scanning Terrestrial Laser Scanning Tree Height Diameter at Breast Height Biomass The implementation of Unmanned Aerial Vehicles (UAVs) and Structure‐from‐Motion (SfM) photogrammetry in assessing forest structures for forest inventory and biomass estimations has shown great promise in reducing costs and labour intensity while providing relative accuracy. Tree Height (TH) and Diameter at Breast Height (DBH) are two major variables in biomass assessment. UAV-based TH estimations depend on reliable Digital Terrain Models (DTMs), while UAV-based DBH estimations depend on reliable dense photogrammetric point cloud. The main aim of this study was to evaluate the performance of multirotor UAV photogrammetric point cloud in estimating homogeneous and heterogeneous forest structures, and their comparison to more accurate LiDAR data obtained from Aerial Laser Scanners (ALS), Terrestrial Laser Scanners (TLS), and more conventional means like manual field measurements. TH was assessed using UAVSfM and LiDAR point cloud derived DTMs, while DBH was assessed by comparing UAVSfM photogrammetric point cloud to LiDAR point cloud, as well as to manual measurements. The results obtained in the study indicated that there was a high correlation between UAVSfM TH and ALSLiDAR TH (R2 = 0.9258) for homogeneous forest structures, while a lower correlation between UAVSfM TH and TLSLiDAR TH (R2 = 0.8614) and UAVSfM TH and ALSLiDAR TH (R2 = 0.8850) was achieved for heterogeneous forest structures. A moderate correlation was obtained between UAVSfM DBH and field measurements (R2 = 0.5955) for homogenous forest structures, as well as between UAVSfM DBH and TLSLiDAR DBH (R2 = 0.5237), but a low correlation between UAVSfM DBH and UAVLiDAR DBH (R2 = 0.1114). This research has demonstrated that UAVSfM can be adequately used as a cheaper alternative in forestry management compared to more highcost and accurate LiDAR, as well as traditional technologies, depending on accuracy requirements. 2022-03-08T10:19:17Z 2022-03-08T10:19:17Z 2021 2022-03-08T10:15:55Z Master Thesis Masters MSc http://hdl.handle.net/11427/35996 eng application/pdf School of Architecture, Planning and Geomatics Faculty of Engineering and the Built Environment |
| spellingShingle | Unmanned Aerial Vehicles Structure‐from-Motion Aerial Laser Scanning Terrestrial Laser Scanning Tree Height Diameter at Breast Height Biomass Onwudinjo, Kenechukwu Chukwudubem Evaluating the performance of multi-rotor UAV-Sfm imagery in assessing simple and complex forest structures: comparison to advanced remote sensing sensors |
| thesis_degree_str | Master's |
| title | Evaluating the performance of multi-rotor UAV-Sfm imagery in assessing simple and complex forest structures: comparison to advanced remote sensing sensors |
| title_full | Evaluating the performance of multi-rotor UAV-Sfm imagery in assessing simple and complex forest structures: comparison to advanced remote sensing sensors |
| title_fullStr | Evaluating the performance of multi-rotor UAV-Sfm imagery in assessing simple and complex forest structures: comparison to advanced remote sensing sensors |
| title_full_unstemmed | Evaluating the performance of multi-rotor UAV-Sfm imagery in assessing simple and complex forest structures: comparison to advanced remote sensing sensors |
| title_short | Evaluating the performance of multi-rotor UAV-Sfm imagery in assessing simple and complex forest structures: comparison to advanced remote sensing sensors |
| title_sort | evaluating the performance of multi rotor uav sfm imagery in assessing simple and complex forest structures comparison to advanced remote sensing sensors |
| topic | Unmanned Aerial Vehicles Structure‐from-Motion Aerial Laser Scanning Terrestrial Laser Scanning Tree Height Diameter at Breast Height Biomass |
| url | http://hdl.handle.net/11427/35996 |
| work_keys_str_mv | AT onwudinjokenechukwuchukwudubem evaluatingtheperformanceofmultirotoruavsfmimageryinassessingsimpleandcomplexforeststructurescomparisontoadvancedremotesensingsensors |