Influence of Drone Altitude, Image Overlap, and Optical Sensor Resolution on Multi-View Reconstruction of Forest Images
Recent technical advances in drones make them increasingly relevant and important tools for forest measurements. However, information on how to optimally set flight parameters and choose sensor resolution is lagging behind the technical developments. Our study aims to address this gap, exploring the...
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| Format: | Article |
| Language: | English |
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MDPI AG
2019-05-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/11/10/1252 |
| _version_ | 1819278283280220160 |
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| author | Erich Seifert Stefan Seifert Holger Vogt David Drew Jan van Aardt Anton Kunneke Thomas Seifert |
| author_facet | Erich Seifert Stefan Seifert Holger Vogt David Drew Jan van Aardt Anton Kunneke Thomas Seifert |
| author_sort | Erich Seifert |
| collection | DOAJ |
| description | Recent technical advances in drones make them increasingly relevant and important tools for forest measurements. However, information on how to optimally set flight parameters and choose sensor resolution is lagging behind the technical developments. Our study aims to address this gap, exploring the effects of drone flight parameters (altitude, image overlap, and sensor resolution) on image reconstruction and successful 3D point extraction. This study was conducted using video footage obtained from flights at several altitudes, sampled for images at varying frequencies to obtain forward overlap ratios ranging between 91 and 99%. Artificial reduction of image resolution was used to simulate sensor resolutions between 0.3 and 8.3 Megapixels (Mpx). The resulting data matrix was analysed using commercial multi-view reconstruction (MVG) software to understand the effects of drone variables on (1) reconstruction detail and precision, (2) flight times of the drone, and (3) reconstruction times during data processing. The correlations between variables were statistically analysed with a multivariate generalised additive model (GAM), based on a tensor spline smoother to construct response surfaces. Flight time was linearly related to altitude, while processing time was mainly influenced by altitude and forward overlap, which in turn changed the number of images processed. Low flight altitudes yielded the highest reconstruction details and best precision, particularly in combination with high image overlaps. Interestingly, this effect was nonlinear and not directly related to increased sensor resolution at higher altitudes. We suggest that image geometry and high image frequency enable the MVG algorithm to identify more points on the silhouettes of tree crowns. Our results are some of the first estimates of reasonable value ranges for flight parameter selection for forestry applications. |
| first_indexed | 2024-12-24T00:09:33Z |
| format | Article |
| id | doaj.art-b83f085666ac4645ad217ca385190e97 |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-12-24T00:09:33Z |
| publishDate | 2019-05-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-b83f085666ac4645ad217ca385190e972022-12-21T17:24:56ZengMDPI AGRemote Sensing2072-42922019-05-011110125210.3390/rs11101252rs11101252Influence of Drone Altitude, Image Overlap, and Optical Sensor Resolution on Multi-View Reconstruction of Forest ImagesErich Seifert0Stefan Seifert1Holger Vogt2David Drew3Jan van Aardt4Anton Kunneke5Thomas Seifert6Department of Forest and Wood Science, Stellenbosch University, Stellenbosch 7599, South AfricaScientes Mondium UG, 85250 Altomünster, GermanyCartography, GIS and Remote Sensing Department, Institute of Geography, Universität Göttingen, 37077 Göttingen, GermanyDepartment of Forest and Wood Science, Stellenbosch University, Stellenbosch 7599, South AfricaChester F. Carlson Center for Imaging Science, Rochester Institute of Technology, Rochester, NY 14623, USADepartment of Forest and Wood Science, Stellenbosch University, Stellenbosch 7599, South AfricaDepartment of Forest and Wood Science, Stellenbosch University, Stellenbosch 7599, South AfricaRecent technical advances in drones make them increasingly relevant and important tools for forest measurements. However, information on how to optimally set flight parameters and choose sensor resolution is lagging behind the technical developments. Our study aims to address this gap, exploring the effects of drone flight parameters (altitude, image overlap, and sensor resolution) on image reconstruction and successful 3D point extraction. This study was conducted using video footage obtained from flights at several altitudes, sampled for images at varying frequencies to obtain forward overlap ratios ranging between 91 and 99%. Artificial reduction of image resolution was used to simulate sensor resolutions between 0.3 and 8.3 Megapixels (Mpx). The resulting data matrix was analysed using commercial multi-view reconstruction (MVG) software to understand the effects of drone variables on (1) reconstruction detail and precision, (2) flight times of the drone, and (3) reconstruction times during data processing. The correlations between variables were statistically analysed with a multivariate generalised additive model (GAM), based on a tensor spline smoother to construct response surfaces. Flight time was linearly related to altitude, while processing time was mainly influenced by altitude and forward overlap, which in turn changed the number of images processed. Low flight altitudes yielded the highest reconstruction details and best precision, particularly in combination with high image overlaps. Interestingly, this effect was nonlinear and not directly related to increased sensor resolution at higher altitudes. We suggest that image geometry and high image frequency enable the MVG algorithm to identify more points on the silhouettes of tree crowns. Our results are some of the first estimates of reasonable value ranges for flight parameter selection for forestry applications.https://www.mdpi.com/2072-4292/11/10/1252UAVdrone-based remote sensinggeometric image resolutionmulti-view reconstructionreconstruction efficiencyreconstruction qualitystructure from motionprecision forestry |
| spellingShingle | Erich Seifert Stefan Seifert Holger Vogt David Drew Jan van Aardt Anton Kunneke Thomas Seifert Influence of Drone Altitude, Image Overlap, and Optical Sensor Resolution on Multi-View Reconstruction of Forest Images Remote Sensing UAV drone-based remote sensing geometric image resolution multi-view reconstruction reconstruction efficiency reconstruction quality structure from motion precision forestry |
| title | Influence of Drone Altitude, Image Overlap, and Optical Sensor Resolution on Multi-View Reconstruction of Forest Images |
| title_full | Influence of Drone Altitude, Image Overlap, and Optical Sensor Resolution on Multi-View Reconstruction of Forest Images |
| title_fullStr | Influence of Drone Altitude, Image Overlap, and Optical Sensor Resolution on Multi-View Reconstruction of Forest Images |
| title_full_unstemmed | Influence of Drone Altitude, Image Overlap, and Optical Sensor Resolution on Multi-View Reconstruction of Forest Images |
| title_short | Influence of Drone Altitude, Image Overlap, and Optical Sensor Resolution on Multi-View Reconstruction of Forest Images |
| title_sort | influence of drone altitude image overlap and optical sensor resolution on multi view reconstruction of forest images |
| topic | UAV drone-based remote sensing geometric image resolution multi-view reconstruction reconstruction efficiency reconstruction quality structure from motion precision forestry |
| url | https://www.mdpi.com/2072-4292/11/10/1252 |
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