Four days, 28 000ha aerial survey by UAS

Post COVID-19 hard-lockdown season has started up with 3DroneMapping’s Uganda office undertaking a 28 000ha aerial survey of a sugar cane estate. The estate required the services of 3DroneMapping to produce highly accurate Digital Terrain Modelling (DTM) and orthophotos. These products were, in turn, to be used by agricultural engineers for the planning and development of irrigation systems as well as for internal use by the estate to maintain and understand the drainage patterns of fields.

Aerial survey over such a large area is no easy feat. Careful flight planning had to be completed in order to maintain efficiency for the flight as well as to retain accuracy for post-processing of data.

Aerial surveys are very hard to produce and unpredictable over homogenous surfaces (terrain that appears similar from above) as the aerial triangulation(AT) process done after the data capture require common points between images to align strips.

3DroneMapping has been testing and implementing a INS/GNSS system into our payload and workflow that negates the need for Aerial Triangulation completely.

This means that strips can now be flown with side overlap as low as 30% (as opposed to the industry standard of 70-75% for UAV captured data). Not only does this double the area that can be covered in a flight, but it dramatically decreases the processing time of the model while allowing the rectification and pointcloud generation of very challenging terrain.

Despite all the delays and challenges that COVID-19 has created, having such a highly efficient data capture method and aircraft meant that the entire 28 000ha contiguous site was captured in 4 days only. Processing of the data to produce raw (unedited or classified pointclouds and orthomosaics) took a further 4 days to achieve.

End to end delivery took only 3 weeks (inclusive of ground control establishment, travel and data transfer)