 Integrating UAVs into Photogrammetry Applications for Agricultural 3D Mapping

Micro-UAVs (Unmanned-Aerial-Vehicles) with a total weight below 5 kg have recently gained considerable attention as alternative image capture platforms in agriculture and other horticulturally-based applications.  Recent technological improvements in image acquisition, camera stabilization, miniaturized optical systems, enhanced payload capacity, complete autonomous navigation and improved the flying performance has resulted in using UAVs as a low cost alternative to the classical manned aerial systems.  And when compared to large aerial survey platforms, UAVs are considered to have greater maneuverability, terrain independent and have the ability to be rapidly set up and deployed.  While photogrammetry is a relatively old practice of determining the geometric properties of an object directly from a digital image, integrating photogrammetry with the use of UAVs is a relative new approach to agricultural, and in particular, vegetable crop production.  Essentially, accurate depth and geometric 3D representation of an object or landscape can be generated from two or more images with overlapping perspectives.  Unique crop measurements, contour lines and terrain elevations, hillshade maps, aspect and slope more data can then be extracted through analysis of information contained within the digital elevation model (DEM), digital surface model (DSM), orthomosaic and point cloud creations when generated through photogrammetry.  Practical tests with two different systems at several locations revealed that both systems were capable of acquiring images in a systematic manner and were useful in 3D image rendering.  The great advantage of utilizing UAV systems is the ability to quickly deliver high temporal and spatial resolution information and to allow a rapid response in a number of critical situations where immediate access to 3D geo-information is crucial.  This presentation reports the state of the art of UAV for photogrammetric applications, giving an overview of different UAV platforms, applications and showing the latest developments of UAV post-image processing.