Device, method and system for determining flight height of unmanned aerial vehicle

A system for determining the flight height of an unmanned aerial vehicle, comprising:

• a data acquiring module configured to acquire a plurality of ground orthographic images in an agricultural operation area and position data and attitude data of an unmanned aerial vehicle at time of acquiring the plurality of ground orthographic images;
• a Gaussian difference pyramid constructing module configured to construct a Gaussian difference pyramid according to pixel points in any two adjacent ground orthographic images;
• a feature point determining module configured to determine the feature points in any two adjacent ground orthographic images according to the Gaussian difference pyramid;
• a matching feature point pair determining module configured to match the feature points in two adjacent ground orthographic images to determine a matching feature point pair, wherein the matching feature point pair determining module specifically comprises:
• a feature description vector constructing unit configured to construct a feature description vector corresponding to each feature point according to the feature points in the ground orthographic image;
• an Euclidean distance determining unit configured to determine the Euclidean distance between the feature points in one ground orthographic image and the feature points in another ground orthographic image according to the feature description vector corresponding to each feature point;
• a matching feature point pair determining unit configured to take the feature point pair whose Euclidean distance is less than the distance threshold as the matching feature point pair, wherein the matching feature point pair comprises two feature points and is located in different ground orthographic images;
• a position determining module of a matching feature point pair in space configured to determine the position of the matching feature point pair in space according to the matching feature point pair;
• a position determining module of an unmanned aerial vehicle in space configured to determine the position of the unmanned aerial vehicle in space according to the position data and attitude data of the unmanned aerial vehicle;
• a relative height determining module configured to determine the relative height of the unmanned aerial vehicle from a canopy of farmland surface crops according to the position of the unmanned aerial vehicle in space and the position of the matching feature point pair in space;
• a flight height determining module configured to determine the flight height of the unmanned aerial vehicle according to the relative height.