Rojective distortion correction algorithm at low altitude photographing

Abstract

An algorithm for projective geometric distortion correction of images at low altitude shooting with a virtual camera is considered. The algorithm is based on the orientation of the virtual camera so that its optical axis is collinear with the normal to the plane of shooting and evaluating a homography matrix linking the coordinates of corresponding pixels of the real and virtual cameras. The homography matrix evaluation is possible based on information from additional sensors – an angular orientation sensor and a rangefinder, or altimeter. Their signals allow one to estimate the camera angular orientation and the distance to the observed plane. The impact of the angular orientation error, estimated using a triaxial microelectromechanical accelerometer, on a criterion-based correction quality is investigated. The experimental results with pre-calibrated cameras Logitech C270 and uEye RE 5240 show that when the roll and pitch errors of the camera orientation are no more than 1° then the correction algorithm with the virtual camera provides a quality index value of at least 0.97.