The Application and Limitations of a Low-Cost UAV Platform and Open-Source Software Combination for Ecological Mapping and Monitoring

Low-cost uncrewed aerial vehicles (UAVs) have become ubiquitous, and advanced UAV systems are affordable for many field ecologists and wildlife managers. Many hobbyist UAVs have been applied to ecological studies, but proprietary software limits their widespread application with little quantification with regards to their accuracy and efficiency in the creation of maps through photogrammetry. Our study addressed these concerns by evaluating a combination of an entry-level UAV and open-source photogrammetry drone mapping software as a low-budget mapping solution for ecologists. Geometrically accurate orthophotograph maps were created from flights at altitudes below 70 m with and without differential global positioning system (d-GPS) ground control points. Object measurement errors were constrained below 30 mm for altitudes up to 70 m, and errors fell below 10 mm at 30 m altitudes with d-GPS points and below 20 mm without the use of d-GPS ground control points. Our analyses provide guidelines that parameterize the requirements for the mapping of smaller areas. Ecological surveys that do not require <50 mm accuracy can benefit from the methods described here, and many ecological studies that are presently using costly software and UAV platforms could save when adopting this approach.