Practical LAI Estimation with DHP Images in Complex Forest Structure with Rugged Terrain
Leaf area index is a key structural parameter for biological and physical processes. Korea is planning to launch CAS500-4 in 2025, so in situ data is needed to validate the leaf area index. Unlike other networks (e.g., NEON and TERN), establishing an elementary sampling unit is difficult in Korea du...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-10-01
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| Series: | Forests |
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| Online Access: | https://www.mdpi.com/1999-4907/14/10/2047 |
| _version_ | 1797573811604815872 |
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| author | Junghee Lee Sungeun Cha Joongbin Lim Junghwa Chun Keunchang Jang |
| author_facet | Junghee Lee Sungeun Cha Joongbin Lim Junghwa Chun Keunchang Jang |
| author_sort | Junghee Lee |
| collection | DOAJ |
| description | Leaf area index is a key structural parameter for biological and physical processes. Korea is planning to launch CAS500-4 in 2025, so in situ data is needed to validate the leaf area index. Unlike other networks (e.g., NEON and TERN), establishing an elementary sampling unit is difficult in Korea due to the complex forest structure and rugged terrain. Therefore, pixel-level correspondence between the satellite product and fisheye footprints is the best way to verify in complex terrain. In this study, we analyzed the spatial footprint of fisheye lenses in different forest types using terrestrial LiDAR data for the first time. The three-dimensional forest structure was analyzed at various viewing zenith angles, and the footprint radius was approximately 3 m at view zenith angle (VZA) 20° and approximately 10 m at VZA 90°. We also analyzed the Z-values from terrestrial laser data and the plant area index on leafless seasons to assess the impact of obstacles, such as tree trunks, under various viewing zenith angles. The analysis showed that the influence of woody components increases dramatically as the VZA exceeds 40°. Such factors influenced the increase in LAI and the decrease in the clumping index as the VZA increased. Overall, we concluded that narrowing VZA between 20° and 40° is appropriate for Korean forests with complex structures. |
| first_indexed | 2024-03-10T21:14:19Z |
| format | Article |
| id | doaj.art-072510fd5e32423cb6023dace83ad8ea |
| institution | Directory Open Access Journal |
| issn | 1999-4907 |
| language | English |
| last_indexed | 2024-03-10T21:14:19Z |
| publishDate | 2023-10-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Forests |
| spelling | doaj.art-072510fd5e32423cb6023dace83ad8ea2023-11-19T16:32:58ZengMDPI AGForests1999-49072023-10-011410204710.3390/f14102047Practical LAI Estimation with DHP Images in Complex Forest Structure with Rugged TerrainJunghee Lee0Sungeun Cha1Joongbin Lim2Junghwa Chun3Keunchang Jang4Forest ICT Research Center, National Institute of Forest Science, Seoul 02455, Republic of KoreaForest ICT Research Center, National Institute of Forest Science, Seoul 02455, Republic of KoreaForest ICT Research Center, National Institute of Forest Science, Seoul 02455, Republic of KoreaDepartment of Forest Environment and Conservation, National Institute of Forest Science, Seoul 02455, Republic of KoreaDepartment of Forest Environment and Conservation, National Institute of Forest Science, Seoul 02455, Republic of KoreaLeaf area index is a key structural parameter for biological and physical processes. Korea is planning to launch CAS500-4 in 2025, so in situ data is needed to validate the leaf area index. Unlike other networks (e.g., NEON and TERN), establishing an elementary sampling unit is difficult in Korea due to the complex forest structure and rugged terrain. Therefore, pixel-level correspondence between the satellite product and fisheye footprints is the best way to verify in complex terrain. In this study, we analyzed the spatial footprint of fisheye lenses in different forest types using terrestrial LiDAR data for the first time. The three-dimensional forest structure was analyzed at various viewing zenith angles, and the footprint radius was approximately 3 m at view zenith angle (VZA) 20° and approximately 10 m at VZA 90°. We also analyzed the Z-values from terrestrial laser data and the plant area index on leafless seasons to assess the impact of obstacles, such as tree trunks, under various viewing zenith angles. The analysis showed that the influence of woody components increases dramatically as the VZA exceeds 40°. Such factors influenced the increase in LAI and the decrease in the clumping index as the VZA increased. Overall, we concluded that narrowing VZA between 20° and 40° is appropriate for Korean forests with complex structures.https://www.mdpi.com/1999-4907/14/10/2047leaf area indexdigital hemispherical photography systemfootprint of fisheye lenscomplex forest structure |
| spellingShingle | Junghee Lee Sungeun Cha Joongbin Lim Junghwa Chun Keunchang Jang Practical LAI Estimation with DHP Images in Complex Forest Structure with Rugged Terrain Forests leaf area index digital hemispherical photography system footprint of fisheye lens complex forest structure |
| title | Practical LAI Estimation with DHP Images in Complex Forest Structure with Rugged Terrain |
| title_full | Practical LAI Estimation with DHP Images in Complex Forest Structure with Rugged Terrain |
| title_fullStr | Practical LAI Estimation with DHP Images in Complex Forest Structure with Rugged Terrain |
| title_full_unstemmed | Practical LAI Estimation with DHP Images in Complex Forest Structure with Rugged Terrain |
| title_short | Practical LAI Estimation with DHP Images in Complex Forest Structure with Rugged Terrain |
| title_sort | practical lai estimation with dhp images in complex forest structure with rugged terrain |
| topic | leaf area index digital hemispherical photography system footprint of fisheye lens complex forest structure |
| url | https://www.mdpi.com/1999-4907/14/10/2047 |
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