A Note on “Parallel” versus “Central” Projection According to Euclid, and, I suspect, to most people, absolute sizes do exist, and may be propagated by something called, “parallel projection”, but, So, in general, Projection of points by lines is Central, Parallel projection is Central Projection from Infinity. Geometries based on this speciality are called, “Affine”. It appears to work for angular measure too. |