Assessment of the feasibility of detecting concrete cracks in images acquired by unmanned aerial vehicles

An 8-rotor unmanned aerial vehicle is used as a working platform. Its motion characteristics in a hovering state are obtained using a non-contact measurement instrument, which, along with the modulation transfer function of its airborne images, indicates the reliability of the airborne images of unmanned aerial vehicles in a hovering state. By installing a laser range finder on the cradle synchronized with the camera shutter to measure the object distance, the pixel resolution of the object distance is obtained. The airborne images are then processed using the MATLAB image processing toolbox, from which the pixels of concrete cracks are extracted. Compared to a static image and direct manual measurements, the airborne image of the unmanned aerial vehicle has higher precision, indicating its wide potential applications as an alternative of the conventional inspection methods of bridge-inspection vehicle and working platforms. •Images of building surface cracks captured by unmanned aerial vehicle.•Using the object distance method to obtain the pixel resolution.•Using a non-contact measurement instrument to test the motion characteristics of system.•The introduction of a modulation transfer function to evaluate image quality.•The consistency between airborne image and the crack measurement instrument results.