Comparison of FOSS4G Supported Equal-Area Projections Using Discrete Distortion Indicatrices

Luïs Duque Moreira de Sousa*, Laura Poggio, B. Kempen

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

7 Citations (Scopus)


This study compares the performance of five popular equal-area projections supported by Free and Open Source Software for Geo-spatial (FOSS4G)—Sinusoidal, Mollweide, Hammer, Eckert IV and Homolosine. A set of 21,872 discrete distortion vindicatrices were positioned on the ellipsoid surface, centred on the cells of a Snyder icosahedral equal-area grid. These indicatrices were projected on the plane and the resulting angular and distance distortions computed, all using FOSS4G. The Homolosine is the only projection that manages to minimise angular and distance distortions simultaneously. It yields the lowest distortions among this set of projections and clearly outclasses when only land masses are considered. These results also indicate the Sinusoidal and Hammer projections to be largely outdated, imposing too large distortions to be useful. In contrast, the Mollweide and Eckert IV projections present trade-offs between visual expression and accuracy that are worth considering. However, for the purposes of storing and analysing big spatial data with FOSS4G the superior performance of the Homolosine projection makes its choice difficult to avoid.
Original languageEnglish
Article number351
JournalISPRS International Journal of Geo-Information
Issue number8
Publication statusPublished - 9 Aug 2019


  • Discrete Global Grid
  • EckertIV
  • Equal-area projection
  • FOSS4G
  • Hammer
  • Homolosine
  • Mollweide
  • Sinusoidal


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