Projection lab

Gnomonic projection: interactive map

Atlas of error · liveGnomonicClick or tap a country to add its outline

Click a country on the map to add its outline.Tap a country on the map to add its outline.

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Gnomonic projection at a glance

Distortion class
Neither equal-area nor conformal
Graticule type
Perspective azimuthal
Creator
Unknown; traditionally, though speculatively, attributed to Thales of Miletus
Year
6th century BC
Area
Distorted: grows rapidly toward the edge of the view; moderate only within about 30° of the center
Shape
Reasonable only near the center; heavily stretched near the edge
Distances
Distorted; true only at the very center of the map
Angles and directions
Distorted; accurate only at the center. In return, every great circle is a straight line

Add countries from the tools panel and drag them to other latitudes. The outline keeps its true shape and area on the globe, so any change in its size on the map shows this projection's distortion. Tissot's indicatrices and the area distortion map show the same effect across the whole world.