Zenithal projection
Also called: Planar projection, Azimuthal projection, True-bearing projection · Topic: Map Projections · NCERT: Class 11, Ch 4 "Map Projections"
Meaning
A zenithal projection is made directly on a flat plane that touches the globe at one point, usually a pole. It is also called a planar, azimuthal or true-bearing projection. Directions from that central point to every other point are shown correctly. It is used mainly for polar areas. With a plane touching at another point, it can also centre a map on any chosen place.
Example
A polar zenithal map of the Arctic, centred on the North Pole, shows the Arctic Ocean ringed by Russia, Canada and Greenland. Such maps help in planning Arctic shipping routes, because the true direction from the pole to every coast can be read off directly.
Don't confuse with
- Mercator's projection: it is often wrongly called azimuthal. It is actually cylindrical and conformal, which means it keeps true shape, not true direction from a centre point.
Related concepts
- Developable surface
- Non-developable surface
- Cylindrical projection
- Conical projection
- Normal projection
- Oblique projection
- Polar projection