Panini projection — where it appears
Named by 2 essays across one field — each of them below, with the objects they name alongside it.
One parameter between two surfaces
Wide architectural views are usually made on a projection with a number attached to it — a family running from the flat plane at one end toward the cylinder at the other, with everybody using the value one. That value has never been given a geometric defence. Measured across the family on this site's own battery, the worst angular error over the field has a minimum, and the minimum is at 1.04.
The lines a surface leaves alone
Only the plane draws every straight line straight, which this site has measured and which gets read as though a curved surface bent everything. It does not. Every curved picture surface here keeps a one-parameter family of world lines exactly straight, and the family is a curve on the sphere of lines rather than a region of it — so a grid of samples finds none of it, which is what the first version of this measurement reported.
Named alongside it
The objects these essays reach for when they reach for this one.
AnisotropyConformalCylindrical projectionDemonstrationPicture surfaceStereographic projectionStraight familyArea scaleBeltramiCube mapDegeneracydegrees of freedom