On accuracy of position estimation from aerial imagery captured by low-flying UAVs

• https://doi.org/10.1016/j.ijtst.2017.02.002

Accuracy analysis, Error propagation, Monte Carlo sampling, Planar scene, Image distortion

The application of low-flying Unmanned Aerial Vehicles (UAVs) for traffic monitoring andsurveillance requires an estimation of position measurement accuracy of monitoredobjects. In this work we aim to analyse and provide insight into the accuracy of positionestimation of objects based on aerial imagery captured by low flying UAV for the purposeof traffic monitoring. The analysis is focused on data gathered by a low-cost action cameramounted on a multicopter UAV flying above a planar scene. We assume a simple, straightforwardmethod of position estimation of object based on homography mapping betweentwo 2D planes derived from the position of images of landmarks - objects with known realworld position. We assume errors caused by inaccuracy of the following values: the landmarks' real world position, the landmarks' and target's real world elevation, and the capturedimage positions of both the landmarks and the target. Additionally, a geometricdeformation of captured frame caused by imperfect camera lenses is considered. The paperfurther analyses the effect of varying magnitude of errors, camera position, incidence angleand both the landmarks' and the target's positions in the scene or captured frame, andcompares the results with real world experiments. The results can be used to estimatethe feasibility and applicability of certain solutions to object position estimation. The toolfor the calculation of the accuracy of position estimation and locating the most suitablecamera pose for a given setup is provided.