Map of Quinta do Lorde  Bay - Madeira Island

Novel approach to enhance coastal habitat and biotope mapping with drone aerial imagery analysis

“…Mapping coastal habitat physiography from the sky. Three aerial survey flights collected 213 images and allowed the construction of an ortho-photomosaic and a DSM 33 covering over 10 ha of a sheltered bay, in the southeastern section of Madeira Island (Fig. 1, Supplementary Fig.…”

“…Based on the Digital Surface Model (DSM), on the reflectance index maps ( Fig. 2a, b) and on the photomosaic generated with Pix4D Mapper (average Ground Sampling Distance, GSD = 5.65 cm/pixel) 33 , we produced a baseline bathymetry map ( Fig. 2c) and an optically derived bathymetry over rocky substrate, with 11 discrete depth classes (each ranging between 1 and 3 m) from the surface to 14 m depth (Figs.…”

“…In the ground, GPS coordinates of easily identifiable features were collected with a handheld GPS (Garmin eTrex 10) to serve as Ground Control Points (GCPs). Compiled imagery was processed and analyzed with the photogrammetry software Pix4Dmapper Pro v4.3, employing advanced multiview imagery and Structure-from-Motion (SfM) algorithms, to construct an ortho-photo mosaic and compute a DSM (Digital Surface Model), a DTM (Digital Terrain Model) and RGB reflectance index 33 . Generated DSM and DTM rasters were used to produce contour layers with 2 m vertical and 1 m horizontal resolutions and a minimum of 200 vertices.…”

“…The procedure was repeated for each of the considered depth categories and resulting shapefiles were compiled and merged into a single file in ArcGIS v10.3.1 54 , with a classification of rocky substrate over the entire extent of the study area. Generated substrate classes were also visually compared with aerial imagery 33 and with dominant substrate data (from georeferenced survey-transects) to assess consistency and perform contextual editing.…”