As a rising navigation technology, vision navigation has many advantages, such as passive measurement, antiinterference,
no accumulation of error and comprehensive parameters, etc. It shows a promising application prospects in
autonomous navigation for UAV. Based on an efficient, reliable and accurate scene matching, a vision altimeter and 3-D
position estimation method are proposed. By matching multiple points between aerial image and reference image, it
estimates UAV's position and height according to photogrammetry. To measure UAV's velocity, a mapless speed
measurement method which tracks ground features between image sequences is introduced. Flight tests had shown the
effectiveness and accuracy of our methods.