A method for operating an unmanned aerial vehicle for acquiring scale information for a structure undergoing non-destructive inspection, comprising: (a) controlling an unmanned aerial vehicle to fly toward a structure (18, 72), wherein the unmanned aerial vehicle is provided with on-board sensors and processing techniques to provide a scale factor usable for displaying a scale indicator on images captured by a video camera; (b) using first and second laser pointers (132a, b) on-board the unmanned aerial vehicle to repeatedly measure a distance (d, nPx) separating first and second spots (106, 108), which are produced by the first and second laser pointers on the surface of the structure, from an image of the first and second spots acquired by the video camera while the unmanned aerial vehicle is flying, wherein a field-of-view of the camera and aim directions of the laser pointers overlap; (c) calculating a separation distance separating the unmanned aerial vehicle from the structure based at least on the distance (d, nPx) separating the first and second spots (106, 108); (d) determining whether the separation distance equals a goal offset; (e) controlling the unmanned aerial vehicle to hover at a first location separated from the structure by the separation distance in response to a determination in step (d) that the separation distance is equal to the goal offset; (f) using the camera on-board the unmanned aerial vehicle to capture a first image of the structure while the unmanned aerial vehicle is hovering at the first location for (g) displaying the first image on a display screen (116, 152); and, when the separation distance is equal to the goal offset, the method further comprises: calculating the scale factor for the first image when displayed on the display screen based at least in part on the separation distance and the field of view of the camera; wherein the scale indicator is overlaid on the first image displayed on the display screen, a value or a length of the scale indicator representing the scale factor. (a) controlling an unmanned aerial vehicle to fly toward a structure (18, 72), wherein the unmanned aerial vehicle is provided with on-board sensors and processing techniques to provide a scale factor usable for displaying a scale indicator on images captured by a video camera; (b) using first and second laser pointers (132a, b) on-board the unmanned aerial vehicle to repeatedly measure a distance (d, nPx) separating first and second spots (106, 108), which are produced by the first and second laser pointers on the surface of the structure, from an image of the first and second spots acquired by the video camera while the unmanned aerial vehicle is flying, wherein a field-of-view of the camera and aim directions of the laser pointers overlap; (c) calculating a separation distance separating the unmanned aerial vehicle from the structure based at least on the distance (d, nPx) separating the first and second spots (106, 108); (d) determining whether the separation distance equals a goal offset; (e) controlling the unmanned aerial vehicle to hover at a first location separated from the structure by the separation distance in response to a determination in step (d) that the separation distance is equal to the goal offset; (f) using the camera on-board the unmanned aerial vehicle to capture a first image of the structure while the unmanned aerial vehicle is hovering at the first location for (g) displaying the first image on a display screen (116, 152); and,