Ground plane rectification — where it appears
Also named here as site plan — the same set of essays touches all of them, so they are one junction rather than several.
The plan hidden in the photograph
Rectifying the ground is the same operation as rectifying a wall, and it turns a photograph into a site plan. The horizon is not an input to it and comes out as a consequence — the plan's points at infinity land on it, at first order, which is the check that the plan is a plan and not a plausible warp.
A carpet and the people on it
A Persian miniature draws the ground as though from above and the figures standing on it as though from in front. The two views want optical axes exactly ninety degrees apart, and the plan view does not shorten a standing figure — it replaces its height with its distance from the point under the eye.
Named alongside it
The objects these essays reach for when they reach for this one.
Site planCamera tiltControl pointsDemonstrationDrawing systemForeshorteningHomographyHorizonline at infinityOcclusionOrthographicPicture plane