zenithal

[zee-nuh-thuh l or, esp. British, zen-uh-]

adjective

of or relating to the zenith; situated at or near the zenith.
(of a map) drawn to indicate the actual direction of any point from the center point.

Origin of zenithal

First recorded in 1855–60; zenith + -al¹

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

It is obvious that all perspective projections are zenithal.
Encyclopaedia Britannica, 11th Edition, Volume 17, Slice 6
Various
All round the horizon is built a black cloud-wall, but the zenithal heaven is clear.
Hours of Exercise in the Alps
John Tyndall
It is clear that perspective and zenithal projections are particular groups of conical projections.
Encyclopaedia Britannica, 11th Edition, Volume 17, Slice 6
Various
Of the above 25 projections, 23 are conical or quasi-conical, if zenithal and perspective projections be included.
Encyclopaedia Britannica, 11th Edition, Volume 17, Slice 6
Various