The Key register Large-scale Topography (in Dutch: Basisregistratie Grootschalige Topografie, BGT) is a digital map of the Netherlands, which records buildings, roads, waterways, land, and railway lines in a uniform way. The map is accurate up to 20 centimeters and contains many details, just as you would see in reality. In short, it documents the spatial organization of our physical surroundings: trees, roads, buildings.