Part of the 1990s research looked at the paper used by Raphael. To do this it was useful to have a record of the size of each individual sheet of paper and how these sheets were stuck together to form the cartoons. To measure each sheet and each overlap by hand would have been very time consuming and somewhat risky for the cartoons. Instead we employed a technique known as photogrammetry, which is commonly used for taking accurate measurements of buildings. It involves taking stereoscopic photographs at known reference points. This information is then fed into a computer to give a detailed print out. As well as giving accurate measurements of the sheets of paper the process also makes it easier to document the size of any creases, tears and other distortions. In theory these measurements could be repeated in the future to monitor any changes.