17 p.This study evaluated the opportunities and challenges of using drones to obtain
multispectral orthomosaics at ultra-high resolution that could be useful for monitoring large and
heterogeneous burned areas. We conducted a survey using an octocopter equipped with a Parrot
SEQUOIA multispectral camera in a 3000 ha framework located within the perimeter of a megafire in
Spain. We assessed the quality of both the camera raw imagery and the multispectral orthomosaic
obtained, as well as the required processing capability. Additionally, we compared the spatial
information provided by the drone orthomosaic at ultra-high spatial resolution with another image
provided by theWorldView-2 satellite at high spatial resolution. The drone raw imagery presented
some anomalies, such as horizontal banding noise and non-homogeneous radiometry. Camera
locations showed a lack of synchrony of the single frequency GPS receiver. The georeferencing process
based on ground control points achieved an error lower than 30 cm in X-Y and lower than 55 cm in Z.
The drone orthomosaic provided more information in terms of spatial variability in heterogeneous
burned areas in comparison with theWorldView-2 satellite imagery. The drone orthomosaic could
constitute a viable alternative for the evaluation of post-fire vegetation regeneration in large and
heterogeneous burned areasS
