Aerial photographs of the Mer de Glace glacier by Eduard Spelternini during his 1909 trans-Alpine balloon flight (left) and a recreation of the image by Dr Kieran Baxter in 2017 (right).
The locations of Spelternini's balloon photographs pinpointed in 3D above a current day digital elevation model (below) and researchers returing to the same point in a helicopter in 2017.
The long view
Time-lapse photography allows us to visualise changes that are normally too slow to see. Over hours or days we can see significant changes in glacial landscapes. To witness the full extent of long-term changes however, a time-lapse can span years or even decades.
The pioneers of aviation and photography unwittingly began such a time-lapse project over 100 years ago, with Eduard Spelterini photographing Alpine glaciers from a balloon as far back as 1909. Now these photographs can be visualised in 3D and compared to the current-day glacier landscape.
In October 2017researchers used GPS points derived from this 3D data to return to the original position that the balloon photographs were taken from in a helicopter. The resulting images can be used for both repeat photography pairs (top right) and is being developed into a 3D animated video - a 100 year time-lapse.