Contour lines to profile

Contour lines or isohypses are a widely used method of representing elevation in a topographic map. It can be used in combination with hillshading to get the realistic threedimensional look of the shaded terrain from the shading and absolut height readings from the contour lines.

There are different kinds of contour lines

Main/Major lines
Multiples of the equidistance from zero level (blue)

Counting lines
Thicker and labeled main contour lines at "round" height values (orange)

Supplementary lines
Between two adjacent main contour lines for a better representation of mostly shallow terrain (green)

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Interpretation of contour lines

Spacing of contour lines
The closer the contours the steeper the slope. The more distant the contours the shallower the slope.
It's very rare that contour lines touch or cross. Only when the terrain is a cliff or an overhang, contour lines can touch over cross each other.

Rule of V- and U-shapes
Rather sharp-pointed V- or U-shaped contours usually are in stream valleys. Water flows perpendicular to the contours. Usually the V or U is pointing upstream. At a stream junction where two V-shaped contours intersect, they form a M- or W-shape.

Rule of O-shapes
Closed loops are usually uphill on the inside with the innermost loop beeing the highest area.
If closed loops represent depressions, this is represented by hachures inside the loop.

The pictures below shows some typical elevation profiles in blue and the corresponding contour lines in orange.

constant slope concave slope convex slope alternating slope


Click on the map at least two times to draw a line. The height profile along this line is then plotted automatically. Click on a path point in the map to delete it or click the Clear button to clear the the entire profile line.
Map and Elevation profile