maths · projective geometry

Two poles of one sphere

The Śrī Yantra turned inside out by circle inversion, then wrapped onto a ball by stereographic projection. On the sphere the inversion is just a flip, and the bindu and infinity are the two poles.

Explore it

Spin the yantra and its inversion on the Riemann sphere, with the plane underneath. Slide the lift, compare stereographic with great circles, and switch the sphere off to see just the plane.

open explorer →

four upward triangles · five downward · the bindu

Triangle coordinates follow a numerical solution of the yantra's concurrency conditions (after Kulaichev and Huet), drawn as 27 lines with 29 triple points.