Multifunctional Ground Control Points based on Wireless System Network for UAS Application
2018 American Society of Agricultural and Biological Engineers. All rights reserved. Unmanned Aerial Vehicles (UAVs) are gaining widespread agricultural usage, including in applications like biomass monitoring, crop yield estimation, disease detection, and irrigation-timing estimation. Image data acquired during flights require some integration with ground control points (GCPs) to improve data accuracy. Typical GCPs require precise geographic coordinates based on expensive surveying equipment for image location of the visible ground marker. However, GPS surveys for typical GCPs are time-consuming, labor-intensive, and costly, especially when data collection is repeated at the same location multiple times in a season, in which case multiple GPS surveys are necessary. An autonomous GCP system based in part on a wireless network was developed for information collection and integration with fixed-wing UAV image data. The GCP system improves the speed of GCP setup and provides data collection advantages that have broad application in agricultural and environmental monitoring. The current GCPs are portable and equipped with an integrated controller, two low-cost GPS modules, a solar panel, a wireless module, and a storage battery, thus simplifying the capture of accurate image data in real-time with a fixed-wing UAV. Results indicate that the current GCPs can be used to improve accuracy in geo-referencing, radiometric calibration, and calibration of crop height estimates from surface models based on structure from motion.