Frame OCS GE (Operation of Large Scale)

The “Ossature” of the OCS GE is a layer of structuring and intermediate vector data that describes the road and rail transport networks on which the OCS GE relies. It is calculated from the internal IGN database from which the TOPO® BD is derived. It produces objects of land cover relatively stable over time which, in future updates, may, for some, serve as a landmark when moving from one vintage to another. It has four main functions: * ensure geographical continuity between territories; * ensure reference geometry; * partition the territories in a homogeneous manner; * ensure spatial cohesion between scales of the territory. The Ossature relies on the main road network and the rail network in service. Each polygon of the frame bears a particular codification according to its production method, it can be extracted from the internal database of the IGN (for road or rail sections, tolls, etc.) or derived from a method of processing in order to comply with the requirements of specifications linked to the OCS GE (cases of fillings at crossroads, spaces between several networks, etc.). The Ossature structure and cuts the territory into areas of seizure of land cover. It is a layer of support for other objects of land use. Each polygon of the frame is coded in soil cover and use.