contouren

Contouren, in cartography often referred to as contour lines or elevation contours, are lines on a map that connect points of equal elevation above a given reference level, usually mean sea level. Their primary purpose is to convey the three-dimensional shape of the terrain in a two-dimensional representation. By following a contour line, one stays at the same height; the space between lines indicates slope.

Contour intervals are chosen to balance readability and detail. The interval is the vertical distance between adjacent contour lines. Larger intervals simplify the map but reduce detail; smaller intervals reveal more terrain features. On many maps every nth line is an index contour, drawn thicker and labeled with its elevation to help reading. Contour patterns reveal landscape forms: concentric closed loops denote hills or depressions; contour loops that cross a ridge produce V-shaped symbols pointing uphill; streams often cut into contours, bending upstream.

In practice, contour lines are generated from field surveys, photogrammetry, or digital elevation models (DEMs). Modern maps and geographic information systems (GIS) store contours as vector lines or as raster-derived products; contouring is a common step in terrain analysis, hydrology, and land-use planning. In addition to topography, contour concepts exist in mathematics and image analysis as level curves of a function or boundaries of shapes.

Because of the Dutch word contouren, the plural form is used in Dutch-language geospatial contexts, while English materials typically use contour lines or elevation contours.