Three-dimensional analytic tools and methods for inspections using unmanned aerial vehicles

A method of inspecting a terrestrial structure using an unmanned aerial vehicle (UAV), wherein the terrestrial structure comprises one or more features, the method comprising:

• operating the UAV along a flight path that at least partially orbits the terrestrial structure one or more times;
• acquiring a plurality of images of the terrestrial structure from the UAV along the flight path, each of the plurality of images being acquired at a different relative position between the UAV and the terrestrial structure, wherein at least some of the plurality of images each include a view of a horizon;
• receiving global positioning system (GPS) coordinates of the UAV at each of the different relative positions;
• computationally generating a three-dimensional (3D) model of the terrestrial structure from the plurality of images;
• computationally aligning the 3D model on three mutually perpendicular axes based at least in part on the views of the horizon included in the at least some of the plurality of images;
• computationally calibrating a scale of the 3D model based at least in part on distances between at least some of the different relative positions;
• and
• calculating at least one of a height or an orientation relative to the horizon of at least one of the features using the 3D model.