UAV survey of a coastal cliff face - Selection of the best imaging angle
| Type | Article | ||||||||||||
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| Date | 2019-06 | ||||||||||||
| Language | English | ||||||||||||
| Author(s) | Jaud Marion 1, Letortu Pauline2, Thery Claire2, Grandjean Philippe3, Costa Stephane4, Maquaire Olivier4, Davidson Robert4, Le Dantec Nicolas5, 6 |
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| Affiliation(s) | 1 : Univ Bretagne Occidentale, IUEM, CNRS, UMS 3113,Technopole Brest Iroise, Rue Dumont dUrville, F-29280 Plouzane, France. 2 : Univ Bretagne Occidentale, IUEM, CNRS, UMR 6554,LETG,Technopole Brest Iroise, Rue Dumont dUrville, F-29280 Plouzane, France. 3 : Univ Lyon 1, CNRS, UMR 5276, Lab Geol Lyon, 2 Rue Raphael Dubois,Batiment GEODE, F-69622 Villeurbanne, France. 4 : Normandie Univ, UNICAEN, CNRS, UMR 6554,LETG, F-14000 Caen, France. 5 : Cerema, Direct Eau Mer & Fleuves, 134 Rue Beauvais, F-60280 Margny Les Compiegne, France. 6 : Univ Bretagne Occidentale, IUEM, CNRS, UMR 6538,Geosci Ocean,Technopole Brest Iroise, Rue Dumont dUrville, F-29280 Plouzane, France. |
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| Source | Measurement (0263-2241) (Elsevier Sci Ltd), 2019-06 , Vol. 139 , P. 10-20 | ||||||||||||
| DOI | 10.1016/j.measurement.2019.02.024 | ||||||||||||
| WOS© Times Cited | 19 | ||||||||||||
| Keyword(s) | UAV, SfM photogrammetry, Tilted camera, Cliff face erosion, Coastal monitoring, Normandy | ||||||||||||
| Abstract | UAVs are relevant for monitoring cliff faces. In this study, several flights are performed with various imaging angles (nadir, 20 degrees, 30 degrees and 40 degrees off-nadir) to assess the impact of the imaging angle on the 3D cliff face reconstruction. Occlusions issues arising with sub-vertical cliffs make nadir surveys nearly irrelevant. The results obtained with 20 degrees, 30 degrees and 40 degrees off-nadir imaging angles are satisfactory regarding texture restitution and accuracy with respectively 5.5 cm, 5.9 cm and 4.9 cm of error, higher tilting angles yielding better reconstructions on sub-vertical or overhanging parts of the cliff. This article also investigates other parameters affecting tiepoint detection on the cliff face, as the effective overlap, the UAV-cliff face distance and the cliff face illumination. Guidelines are provided for UAV survey parameterization, aiming at capturing the whole cliff face with a good trade-off between distance to the cliff, flight height and spatial resolution of the photographs. |
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