Photographs are unique «contemporary witnesses» that document the status of a landscape or region at a specific point in time. Aerial and satellite images are ideal large-scale information sources and form a valuable basis for the implementation of a broad variety of projects. Image data are especially useful for documenting changes in the landscape, as well as for producing observation series or for use as a planning instrument. swisstopo provides customised aerial images upon request, and also supports the acquisition and further processing of satellite images.