Unmanned aerial photogrammetric survey of approx. 700 ha. in Miri, Sarawak for flood mitigation planning

Digital Surface Model of target area

Contour of target area

The goal of this project was to generate a DTM, DSM, contour, and orthomosaic of a largely undeveloped area near the Miri aerodrome for flood mitigation planning. Image acquisition of the 728 ha area was carried out in 5 days using the senseFly eBee Classic, with an average ground sampling distance (GSD) of 3.41 cm. A total of 39 ground control points (GCPs) in Timbalai 1948/Borneo RSO coordinate system, established using Trimble R5’s, was employed to align and georeferenced the photogrammetric data. Pix4Dmapper and Global Mapper were used to process the images and generate the final outputs.

1 of 39 Ground control points (GCPs)

SenseFly eBee drone

Palm Oil Plantations within the target area

The close proximity of the target area to an aerodrome proved to be the most challenging aspect of the project. Through side-by-side flight planning with the local civil aviation authority (DCA), eBee flights were restricted to below 120 m and only when no other aircraft occupied the same airspace. The relatively low flight height imposed by DCA meant that photogrammetric reconstruction of homogenous vegetated areas was an expected issue in data processing. Our team at UAS overcame this limitation by utilising a criss-cross flight pattern to obtain greater image overlap of the potentially problematic artefacts. No uncalibrated images were obtained in Pix4D and all outputs were generated with satisfactory performance.