Official Publication No. 70 (2019)
More and more countries have digitised or are currently digitising their archives of aerial images. They are a unique and relatively unexplored means to chronicle land-cover information over the past 100 years with very high spatial resolution. Such data provide a relatively dense temporal sampling of the territories. 3D information can even be retrieved since many surveys were performed under photogrammetric conditions. Therefore, many long-term environmental monitoring studies can be based on the analysis of these very rich time series of images.
We have noticed in the last years an increasing number of scientific papers processing archival airborne images. In a timely manner, it appears necessary to evaluate the current status of the archive digitisation process in Europe, up to the distribution policy. This document reports the outputs of a poll carried out by the French National Institute for Geographic and Forest Information (IGN-France) with the help of Swisstopo.