Representation of the points whose coordinates were identified in the aerial photogrammetric restitution phase. In order to complete the VTR network, and to make the distribution of the known points uniform, especially in high mountain areas (average altitude above 1500 m. ) or heavily wooded, a certain number of photogrammetric refinement points (PRF) have been set up, determined by aerial triangulation or in any case by numerical restitution. They are made up of photographic details that are certainly identifiable on the ground and of adequate fineness (crossroads and crossroads, poles and pylons, etc...). The PRFs are marked on the paper by a circle with flaps. The monographs of the points in PDF format are associated with the representation. Not all monographs contain numerical coordinates, but they are reported in the database anyway.
