Year: 2026
Type: article
Abstract: Hourglass is an equal-area pseudocylindrical map projection developed by John P. Snyder in mid 1940s. It was never published in a detailed way by its author, and only a couple of references exist in the literature since 1991, both of them including a picture but without any mathematical description. In this work, the equations of the projection for the sphere are derived, for both direct and inverse problems, together with a generalization that allow meridians not restricted to straight lines as in the original Snyder version. We prove also that the cylindrical equal-area projection can be derived as a limit case of the generalized Hourglass version. The Hourglass projection was designed only to demonstrate that area preservation in a map projection is a parameter that must never be evaluated in isolation; it is a projection not useful in real applications in surveying nor in cartography, but its formulation, as any other thought of John P. Snyder on map projections, deserves to be known.
Source: Journal of Surveying Engineering
Authors: J. Jimenez Shaw, J. L. G. Pallero
Institution: Universidad Politécnica de Madrid
Language: English
Subfield: Geography, Planning and Development
Field: Social Sciences
Domain: Social Sciences
Open Access status: green
Funder: Comunidad de Madrid
Awards: G3197693816, G638709848
OpenAlex ID: W7171399445