This book contains some of the projects developed over the course of 4 years at the multimedia and interactivity laboratory (LMI), situated at Itajubá, Brazil, inside the Federal University of Itajubá (UNIFEI). The development of these works contributed to the formation of many students from graduate and undergraduate courses. One of our research interests at LMI is the navigation and collision avoidance of Unmanned Aerial Vehicles (UAVs), popularly known as drones. The works contained in this book show our efforts in trying to achieve these objectives through different strategies. The first three works investigate the use of Self Organizing Maps and Artificial Neural Networks to process the data obtained by a camera mounted in the UAV. This information can be useful to detect different types of terrain and help the UAV to navigate safely. Two of our works focused on the use of image processing techniques to detect obstacles in front of the UAV. In this case the UAV is able to avoid the obstacles and safely navigate in an indoor environment.