Visual Plane
every picture states the point it is correct from
Concept

Inaccessible vanishing point — where it appears

A vanishing point falling off the drawing board, and the construction that divides a line toward it without drawing it. Two transversals divided in proportion give the same pencil exactly, because the construction is a perspectivity fixed by three pairs rather than by the point.

Named by 2 essays across one field — each of them below, with the objects they name alongside it.

to the vertex, 450 px furthercorrect from 22 cm, at 160 mm wide5 courses · 1e-13 px

Dividing to a point off the board

A wall turned forty degrees to the view has its vanishing point 0.65 canvas widths past the edge of the paper, and the construction that aims every course at it without ever reaching it is exact to 1e-13 px. Putting the vertex where the sheet ends instead costs 20.9 px, which on this wall is 300 mm of masonry, and nothing in the drawing says so.

construction · Offboard the picture plane, in planto the observer, 208 px further downcorrect from 12 cm, at 160 mm widestation 520 px

Two rules for one pavement

Vignola set out two rules for laying a tiled floor and asserted that they agree. Executed from the same ground line and the same free parameter they agree to 2e-13 px; executed from the numbers their own wordings invite they part by 24 px. The quantity that separates them is the distance the reader has to stand at, and neither rule names it.

construction · Tworules

Named alongside it

The objects these essays reach for when they reach for this one.

HorizonTransversalViewing distanceCentric pointConditioningcostruzione legittimaCross-ratiodegrees of freedomDistance pointFree parameterPavementPencil

All concepts