A Review of Using Visual Odometery Methods in Autonomous UAV Navigation in GPS-Denied Environment

This review paper centers on strategies employed for location determination in regions lacking GPS signals. It primarily explores a range of vision-based methods tailored for this purpose, categorizing them accordingly. The article delves into the utilization of optical flow for feature extraction-based Visual Odometry (VO) and delves into advanced optical flow estimation methods that hinge on deep learning techniques. It compares the efficacy and practical applications of frequently utilized visual localization methods while also checking the efficiency of previous researches by reapplying the algorithms to new data and comparing the results.