Fuente: Wipo "precision agriculture" Systems and methods for providing an accurate determination of above ground level (AGL) altitude for use in precision agriculture. A 3D computer model of an agricultural field is generated by analyzing frames of a video of the agricultural field that have been obtained by a camera on an unmanned aerial vehicle flown over the agricultural field and generating 3D points that are used to create the 3D computer model. The 3D computer model is then scaled by fusing each 3D point with navigation sensor data associated with each frame. An AGL altitude for each 3D point of the scaled 3D computer model can then be determined. In another embodiment, a trajectory of the unmanned aerial vehicle can be determined and used to generate a georeferenced map using images captured by the camera.