Unmanned Aerial Vehicles (UAVs) are versatile machines that can be used in a variety of applications, such as automatic monitoring of crops, large public area control, maritime supervision aid, etc. Autonomous flying is a desirable feature for UAVs, especially for those that are frequently used in monitoring and inspection of large areas. In some situations, global positioning system is not guaranteed or its error might be too large, hence other methods of local position feedback are required. As an approximation of the above mentioned applications, this project presents a path following controller design based in a visual-based line detection algorithm using the image frames captured by the UAV downwards facing camera. A study of the environmental impacts of the use of the UAV is presented as well as ethics and citizenship aspects. Finally, the experimental results are discussed and final conclusions are presented.