I've been given permission to share the following output files from a recent flight over White Island, off the coast of the Bay of Plenty. I flew directly overhead the steaming crater at 6000 feet, whilst the camera operator in the rear of the aircraft shot a line of overlapping images through a special hatch in the floor. After landing, the film roll then got sent away, processed and returned to our head office a few days later ready to be scanned in at an extraordinary high resolution digital format for further analysis. Once on the in house computer system, this allows for the generation of simple .JPEG previews of individual frames if required, scaled down from several gigabytes to just 1 megabyte in this 1000 pixels wide example:
Next is where the real magic happens. I don't understand the process completely, but my novice attempt at an explanation goes as follows: The scale of the aerial photographs get geometrically corrected to remove angular distortions and the vertical variations from the topography underneath. The resulting flattened orthograph can then be used to accurately measure distances, depths and volumes relative to known GPS points on a countrywide database. The clever software it gets fed into reads thousands of X,Y and Z coordinates from the photography data, and is then able to create three dimensional 'point cloud' reconstructions of the terrain that was below the flight path. This quick video that I put together on one of the work computers this morning, showcases the interesting volcanic landscape from the above picture set, comprising of over 12 million separate data points. The accuracy achieved to display each individual contour like this is fascinating to me!