The drone will take numerous high-resolution overlapping photos (80 to 90% overlap) along the length of the feature or structure. From these images, the software can then create a map, drawing or 3D model of the structure using photogrammetry, which is the science of making measurement from photographs. To overlap photographs of a structure or feature by 80 to 90% would be impossible to be done accurately just trough good pilot navigation, and this is where the software comes into its own.
The resultant map or model is highly detailed and accurate representation of the structure or feature with all measurements in place and the beauty of the software is that it will remember the waypoints, so it can revisit the feature at any time as part of a regular maintenance or inspection programme at any time in the future.