Bitou bush surveillance UAV trial

Abstract

Bitou bush (Chrysanthemoides monilifera sub-species rotundata), a native of South Africa, has the ability to outcompete and smother native coastal dune vegetation. Infestations in Queensland have been dramatically reduced since the 1980s, with only isolated plants being found in the field today. Ground surveillance is currently carried out twice yearly involving teams of field staff surveying densely vegetated areas in an emu parade to maximise detection of both mature plants and seedlings. Some of the coastal vegetation has become too dense making it nearly impenetrable for ground surveillance. The risk of not detecting plants in this area has become high due to lack of visibility. Another technique of monitoring and detection is required to ensure eradication. This project aimed to develop a surveillance protocol and strategy using unmanned aerial vehicles (UAVs) also commonly known as drones to become a permanent component of the Bitou bush eradication project. An innovative company, Aspect UAV Imaging, worked with Biosecurity Queensland to develop suitable UAV technology. Test flights were carried out to determine the required camera resolution, the flight height which provided proper resolution and the amount of overlap using a systematic pattern over the test area. Images were processed and enhanced post-flight to aid in the detection of Bitou bush. Ortho-images were georeferenced with colour enhancement and trialled with a series of programs to determine the best application and usability. Images processed by researchers from the Queensland University of Technology using automated classification algorithms gave promising results. With improvements in technology, the regular use of UAVs for surveillance will soon complement many aspects of weed monitoring.