The Littrow projection is the only conformal retroazimuthal map projection. A retroazimuthal projection is one in which the direction to a fixed location B (the bearing at the starting location A of the shortest route) corresponds to the direction on the map from A to B.
The Littrow projection allows direct measurement of the azimuth from any point on the map.
The Littrow projection was created in 1833 by Joseph Johann Littrow (1781 – 1840). It is sometimes referred to as a Weir Azimuth diagram.