To survey areas that cannot be easily reached, a UAV operated by a CAA approved pilot can be used.
High-resolution photographs or video can highlight defects not otherwise seen by conventional methods.
UAVs are quick to set up and can be used to gather quality data in a fraction of the time it takes to erect ladders, scaffolding or even cherry pickers.
It is possible, by using photogrammetric methods employed in forensics to actually measure from images. Not only can defects be identified, they can be quantified as well.