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Cartographic deformations in a parabolic visual field map
Author(s) -
Lindblom Bertil
Publication year - 1988
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.1988.tb04068.x
Subject(s) - field (mathematics) , visual field , cartography , geology , optometry , geography , geodesy , computer vision , computer graphics (images) , computer science , mathematics , optics , physics , medicine , pure mathematics
. Visual fields are traditionally represented in the polar azimuthal equidistant projection. In this map, field areas are increasingly exaggerated with increasing visual angle. To facilitate description of central field defects, enlargement of the central visual field by a parabolic, non‐linear projection has been proposed. The cartographic deformations associated with this projection were studied by using mathematical isopter models. A change from equidistant to parabolic projection not only altered relative isopter sizes but also their shapes. Also, the normal nasal‐temporal asymmetry was obscured. Thus, the parabolic projection may conceal some types of visual field defects, e.g. loss of the temporal cresent. Neither projection represented surface areas correctly. It is argued that the area‐true Lambert's projection would be ideal for visual field representation.