The BD OCS GE is a vector database for the description of the land cover of the entire metropolitan territory and the overseas departments. It is a national repository, constituting a base, usable at national and local level. It contributes to the calculations of indicators required by urban planning documents (PLU, SCoT). It is also compatible (as far as possible) with existing land use layers. It is based on an open model separating land cover and land use (called a 2-dimensional model) with precision based on the large-scale repository (RGE®) and temporal consistency (concept of vintage) allowing updates to follow changes in space consumption. The BD OCS GE is made up of administrative areas (group of municipalities, department or region) while ensuring geographical and thematic continuity at the national level. Ultimately, it will represent a continuous partition of the territory. Its production is based on existing data extracted from internal IGN databases as well as any other data that can be used from national or local repositories (graphic parcel register, regional OCS, etc.). The BD OCS GE is based on the national nomenclature recommended by the National Council for Geographic Information (CNIG), developed by the Center for Studies and Expertise on Risks, the Environment, Mobility and Development (CEREMA), under the supervision of the ministry in charge of ecology, sustainable development and energy (MEDDE.DGALN). The BD OCS GE complies with the national production recommendations that accompany the national nomenclature. It is based on an intermediate data layer, the national repository of the main networks constituting the "National Framework". It has four main functions: - ensuring geographical continuity between territories; - ensure a reference geometry; - partition the territories in a homogeneous way; - ensure spatial cohesion between scales of the territory.
