The Bonne projection (a pseudoconical equal-area map projection) was frequently adopted for 18th and 19th century mapping, but being equal area rather than conformal its use for topographic mapping was replaced during the 20th century by conformal map projection methods.
The Bonne projection is a map projection that resembles the shape of a heart (see picture). The Bonne projection is used in Portugal.
Bonne Projection
To convert Bonne coordinates, the following parameters have to be set:
