Processes and media developed over the centuries, so that by the 16th century Giambattista Della Porta and Jacopo Chimenti had created representations of relief using successive drawings of the same subject, seen from slightly different angles.

In 1832, the advent of photography marked another breakthrough. The first stereoscopic images resulted from pairing 2 cameras. Then, in 1856, the first camera with two lenses was created, enabling photographers to easily take several photos of the same object from slightly different angles. This method has been developed, and is now applied to satellite imagery.

Stereoscopic images produced with HRS are analysed, after processing on the ground, to become 3D digital elevation models (DEMs).

The data are then used in geographic information systems (GIS) to build up a global database called Reference3D. Within 4 years, HRS already has ben able to cover over 100 million square kilometres.

HRS is financed by CNES and its subsidiary, Spot Image, as well as by Astrium, in a cooperative operation that is a fine illustration of CNES's partnership policy.