Comparison of Digital Elevation Model from Consumer Grade Drone for Shallow-Water Bathymetry at Redang Island Marine Park, Terengganu.

Abstract

The most common and best method of obtaining shallow-water bathymetry is using a single-beam echosounder (SBES). There were numerous studies on drone DEM for shallow river basins and coastal areas, but not on shallow-water coral reef areas. Thus, this study was carried out to compare the DEM produced by a consumer-grade drone with the bathymetry obtained from SBES for a shallow-water reef area in Redang Island Marine Park. The DJI Phantom 4 with 1/2.3” CMOS camera sensor was used to capture images using automated DroneDeploy application. Besides, the bathymetry survey was conducted using SBES Hummingbird 581iHD Down ImagingTM. The data were processed using DroneDeploy Proprietary Map Engine (Drone) and Hypack Max 2014 (SBES), which then were extracted and compared. The results indicated the shallowest level at the sandy beach
(0m to -1m) had the lowest RMS error (RMSE: 0.230m, R2 : 0.499), in comparison with other depth classes at both sandy beach and rocky shore. Therefore, the bathymetry derived from a consumergrade drone DEM, based on an RGB sensor is not suitable to be used for safety navigation mapping, but it can be applied for other coastal management purposes, such as shoreline mapping and monitoring.
Keywords: Drone, Bathymetry, Shallow Water Reef, Digital Elevation Model (DEM), Single Beam
Echosounder (SBES)