I use Agisoft Photoscan Pro and it does everything I need it to and I think is more intuitive to use than other software. For Remotely Piloted Aircraft (RPA/uav) survey work you may find that using ground control points (positions recorded with GPS) will be important, depending on what you want to do with the outputs. This all works very well with Photoscan and costs less than Pix4D..... Have a look at www.aerial-cam.co.uk
Hello Sebastian, yes we have to have a Remote Pilot Qualification (Ground School and Flight Test) and be approved by the CAA. This enables the correct insurance and for each operation land owner permissions and risk assessments are required. If in controlled airspace we also need to contact air traffic control.