Orthogonal involution, also called absolute involution, is the involution on the line at infinity that maps orthogonal directions to each other.
Orthogonal Involution
See also
Involution, Line at InfinityThis entry contributed by Floor van Lamoen
Explore with Wolfram|Alpha
Cite this as:
van Lamoen, Floor. "Orthogonal Involution." From MathWorld--A Wolfram Web Resource, created by Eric W. Weisstein. https://mathworld.wolfram.com/OrthogonalInvolution.html