A method of iterative image normalization for tasks of visual navigation of UAVs

Abstract

The work deals with a method of eliminating the perspective distortion of an image acquired from an unmanned aerial vehicle (UAV) camera in order to transform it to match the parameters of the satellite image. The normalization is performed in one of the two ways. The first variant consists in the calculation of an image transformation matrix based on the camera position and orientation. The second variant is based on matching the current frame with the previous one. The matching results in the shift, rotation, and scale parameters that are used to obtain an initial set of pairs of corresponding keypoints. From this set four pairs are selected to calculate the perspective transformation matrix. This matrix is in turn used to obtain a new set of pairs of corresponding keypoints. The process is repeated while the number of the pairs in the new set exceeds the number in the current one. The accumulated transformation matrix is then multiplied by the transformation matrix obtained during the normalization of the previous frame. The final part presents the results of the method that show that the proposed method can improve the accuracy of the visual navigation system at low computational costs.