Methods for tree cover extraction from high resolution orthophotos and airborne LiDAR scanning in Spanish dehesas
Dehesas are high value agroecosystems that benefit from the effect tree cover has on pastures. Such effect occurs when tree cover is incomplete and homogeneous. Tree cover may be characterized from field data or through visual interpretation of remote sensing data, both time-consuming tasks. An alte...
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Universitat Politècnica de València
2019-06-01
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| Series: | Revista de Teledetección |
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| Online Access: | https://polipapers.upv.es/index.php/raet/article/view/11320 |
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| author | I. Borlaf-Mena M. A. Tanase A. Gómez-Sal |
| author_facet | I. Borlaf-Mena M. A. Tanase A. Gómez-Sal |
| author_sort | I. Borlaf-Mena |
| collection | DOAJ |
| description | Dehesas are high value agroecosystems that benefit from the effect tree cover has on pastures. Such effect occurs when tree cover is incomplete and homogeneous. Tree cover may be characterized from field data or through visual interpretation of remote sensing data, both time-consuming tasks. An alternative is the extraction of tree cover from aerial imagery using automated methods, on spectral derivate products (i.e. NDVI) or LiDAR point clouds. This study focuses on assessing and comparing methods for tree cover estimation from high resolution orthophotos and airborne laser scanning (ALS). RGB image processing based on thresholding of the ‘Excess Green minus Excess Red’ index with the Otsu method produced acceptable results (80%), lower than that obtained by thresholding the digital canopy model obtained from the ALS data (87%) or when combining RGB and LiDAR data (87.5%). The RGB information was found to be useful for tree delineation, although very vulnerable to confusion with the grass or shrubs. The ALS based extraction suffered for less confusion as it differentiated between trees and the remaining vegetation using the height. These results show that analysis of historical orthophotographs may be successfully used to evaluate the effects of management changes while LiDAR data may provide a substantial increase in the accuracy for the latter period. Combining RGB and Lidar data did not result in significant improvements over using LIDAR data alone. |
| format | Article |
| id | doaj-art-40f3ff1534174b4bb9a6c8432d6f7dd7 |
| institution | DOAJ |
| issn | 1133-0953 1988-8740 |
| language | English |
| publishDate | 2019-06-01 |
| publisher | Universitat Politècnica de València |
| record_format | Article |
| series | Revista de Teledetección |
| spelling | doaj-art-40f3ff1534174b4bb9a6c8432d6f7dd72025-08-20T02:42:58ZengUniversitat Politècnica de ValènciaRevista de Teledetección1133-09531988-87402019-06-0153173210.4995/raet.2019.113207527Methods for tree cover extraction from high resolution orthophotos and airborne LiDAR scanning in Spanish dehesasI. Borlaf-Mena0M. A. Tanase1A. Gómez-Sal2University of AlcaláUniversidad de AlcaláUniversidad de AlcaláDehesas are high value agroecosystems that benefit from the effect tree cover has on pastures. Such effect occurs when tree cover is incomplete and homogeneous. Tree cover may be characterized from field data or through visual interpretation of remote sensing data, both time-consuming tasks. An alternative is the extraction of tree cover from aerial imagery using automated methods, on spectral derivate products (i.e. NDVI) or LiDAR point clouds. This study focuses on assessing and comparing methods for tree cover estimation from high resolution orthophotos and airborne laser scanning (ALS). RGB image processing based on thresholding of the ‘Excess Green minus Excess Red’ index with the Otsu method produced acceptable results (80%), lower than that obtained by thresholding the digital canopy model obtained from the ALS data (87%) or when combining RGB and LiDAR data (87.5%). The RGB information was found to be useful for tree delineation, although very vulnerable to confusion with the grass or shrubs. The ALS based extraction suffered for less confusion as it differentiated between trees and the remaining vegetation using the height. These results show that analysis of historical orthophotographs may be successfully used to evaluate the effects of management changes while LiDAR data may provide a substantial increase in the accuracy for the latter period. Combining RGB and Lidar data did not result in significant improvements over using LIDAR data alone.https://polipapers.upv.es/index.php/raet/article/view/11320Low-density airborne LidarPNOATree coverQuercus ilex |
| spellingShingle | I. Borlaf-Mena M. A. Tanase A. Gómez-Sal Methods for tree cover extraction from high resolution orthophotos and airborne LiDAR scanning in Spanish dehesas Revista de Teledetección Low-density airborne Lidar PNOA Tree cover Quercus ilex |
| title | Methods for tree cover extraction from high resolution orthophotos and airborne LiDAR scanning in Spanish dehesas |
| title_full | Methods for tree cover extraction from high resolution orthophotos and airborne LiDAR scanning in Spanish dehesas |
| title_fullStr | Methods for tree cover extraction from high resolution orthophotos and airborne LiDAR scanning in Spanish dehesas |
| title_full_unstemmed | Methods for tree cover extraction from high resolution orthophotos and airborne LiDAR scanning in Spanish dehesas |
| title_short | Methods for tree cover extraction from high resolution orthophotos and airborne LiDAR scanning in Spanish dehesas |
| title_sort | methods for tree cover extraction from high resolution orthophotos and airborne lidar scanning in spanish dehesas |
| topic | Low-density airborne Lidar PNOA Tree cover Quercus ilex |
| url | https://polipapers.upv.es/index.php/raet/article/view/11320 |
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