Embodiments described herein provide various examples of an automatic obstacle avoidance system for unmanned vehicles using embedded stereo vision techniques. In one aspect, an UAV capable of performing autonomous obstacle detection and avoidance is disclosed. This UAV includes: a stereo vision camera set coupled to the one or more processors and the memory to capture a sequence of stereo images; and a stereo vision module configured to: receive a pair of stereo images captured by a pair of stereo vision cameras; perform a border cropping operation on the pair of stereo images to obtain a pair of cropped stereo images; perform a subsampling operation on the pair of cropped stereo images to obtain a pair of subsampled stereo images; and perform a dense stereo matching operation on the pair of subsampled stereo images to generate a dense three-dimensional (3D) point map of a space corresponding to the pair of stereo images.