ANALYSIS OF EXTERIOR ORIENTATION PARAMETERS ON MONOPLOTTING PROCEDURE FOR AVOIDING OBSTACLES IN UAV REAL-TIME ROUTING

Abstract

Unmanned Aerial Vehicles (UAVs) are adopted in different applications, such as mapping, logistics, and surveillance. For some applications, it is important to identify people or objects to be tracked in the image and define their coordinates in the object space. It can be done by using a photogrammetric process called Monoplotting. Moreover, by applying the Propagation of Variance and Covariance, the standard deviation from planimetric coordinates can be defined as an Exterior Orientation Parameter (EOP) function. This work evaluates the planimetric accuracy achieved using points defined in UAV images and the impact of EOPs precision. Two UAV images, the Digitals Surface Model (DSM) from the corresponding areas, the EOPs (X0, Y0, Z0, ω, φ, κ), and the platform/sensors characteristics were used for the experiments. Results showed that planimetric precision is low when using UAVs with a low-cost positioning system, especially if the points of interest in the image are far from the nadir. For UAVs with a high-precision positioning system, Inertial Measurement Unit (IMU) system is the one with a higher influence on the accuracy of planimetric coordinates, especially for oblique photographs (essential for UAV routing when avoiding obstacles). The impact of the IMU system precision increases in oblique photographs, this alerts to attention for UAV flight real-time routing guided by obstacles mapping using images.