The potential of Pléiades images with high angle of incidence for reconstructing the coastal cliff face in Normandy (France)

https://doi.org/10.1016/j.jag.2019.101976Get rights and content
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Highlights

  • The potential of coastal cliff face 3D reconstruction using pairs of Pléiades images with high angle of incidence is tested.

  • The cliff face 3D reconstruction is challenging in Normandy because of the subverticality of the cliffs and of the north-oriented cliff face.

  • 3D reconstructions of the cliff face are compared using ASP® and ERDAS IMAGINE®.

  • ERDAS IMAGINE® provides more reliable point clouds than ASP®.

  • The amount of noise from raw images and the shadow intensity on the cliff face mostly explain the quality of 3D point cloud reconstructions.

Abstract

To monitor chalk cliff face along the Normandy coast (NW France) which is prone to erosion, we tested the potential of cliff face 3D reconstruction using pairs of images with high angle of incidence at different dates from the agile Pléiades satellites. The verticality aspect of the cliff face brings difficulties in the 3D reconstruction process. Furthermore, the studied area is challenging mainly because the cliff face is north-oriented (shadow). Pléiades images were acquired over several days (multi-date stereoscopic method) with requested incidence angles until 40°. 3D reconstructions of the cliff face were compared using two software: ASP® and ERDAS IMAGINE®. Our results are twofold. Firstly, despite ASP® provides denser point clouds than ERDAS IMAGINE® (an average of 1.60 points/m² from 40° incidence angle stereoscopic pairs on the whole cliff face of Varengeville-sur-Mer against 0.77 points/m² respectively), ERDAS IMAGINE® provides more reliable point clouds than ASP® (precision assessment on the Varengeville-sur-Mer cliff face of 0.31 m ± 2.53 and 0.39 m ± 4.24 respectively), with a better spatial distribution over the cliff face and a better representation of the cliff face shape. Secondly, the quality of 3D reconstructions depends mostly on the amount of noise from raw images and on the shadow intensity on the cliff face (radiometric quality of images).

Keywords

Pléiades imagery
High incidence angle images
Cliff face erosion
3D reconstruction
Normandy (France)

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