Low-cost aerial nadir photography and fast georeferencing

The decrease in costs of UAV’s purchasing and operating is leading to a growing use by the broader society, of aerial nadir photography, sometimes mistakenly confused with digital airborne imaging. The small payload of low-cost UAVs involves installing compact and lightweight cameras, without INS-GNSS micro-platforms, which are the technological system able to sync shooting with the position and attitude of the aircraft. It follows that the flight path and the digital images are not georeferred and therefore the use of aerial photography from low-cost UAVs can not be used for technical purposes. This paper is the first output of a research focused on georeferencing of digital images through the flight paths, and conversely on the flight path drawing through the geolocation of nadir images. Both application phases are developed in open source GIS software. According to the conference topics, this paper discusses aspects of projective geometry related to photography, the flight path and mutual synchronisation. The data being processed are from airborne flights in order to solve geometric problems in the best possible configuration, to be subsequently applied to acquisitions by UAVs.