The ultimate goal of the SOAR program is to develop robust hardware and algorithms for low light, passive terrain sensing. The SOAR system will provide NASA with a solution for real-time obstacle avoidance for large and small unmanned air platforms. During Phase-I, we will collect images with all of the leading low-light camera technologies. The image data will be used to derive, test, and enhance a passive terrain sensing algorithm based-on state-of-the-art, visual odometry and dense stereo algorithms. At the end of Phase-I, we will recommend the optimal hardware, algorithm, and computing platform for full prototype development during Phase-II. The factors used to make the recommendation include cost, range accuracy, size, power consumption, algorithm execution time, etc.