Base map

A base map (in Turkish practice, the halihazır harita, literally a map of the present state) records an area exactly as it is on the ground. It is produced by survey and shows existing buildings, roads, pavements, walls, trees, poles, spot levels and contour lines. In Turkey, zoning plans are largely drawn on top of these maps.

Its place in a project

Before designing anything on a plot, one of the first documents an architect asks for is the base map. It shows how the plot relates to its surroundings, where the neighbouring buildings stand, the road levels and the slope of the land. The site plan is usually drawn over it. If the map is out of date, the drawings and the site may not agree, so it is checked with a fresh survey when needed.

Base map versus topographic map

The two terms are often used loosely. A topographic map focuses on the form of the land, while a base map also records the built environment in detail: everything people have put there. In architectural work they usually come together on the same sheet.

For visualization, the base map is a reliable starting point for modelling surrounding buildings and streets, so the building in the render sits on the street it will actually stand on.