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

Depth scaling — where it appears

The proportionality between a mark's distance from the centre of projection and the size that mark has to be drawn at. It is why a design cast onto a surface three metres further away has to be painted half again as large, and why parts of one picture on surfaces at different depths are at different scales.

Named by 3 essays across 3 fields — each of them below, with the objects they name alongside it.

0.6× the page48 mm×8.3 at 4000.8× the page64 mm×6.3 at 4001.0× the page80 mm×5.0 at 4001.4× the page112 mm×3.6 at 4002.0× the page160 mm×2.5 at 4003.0× the page240 mm×1.7 at 4004.5× the page360 mm×1.1 at 4007.0× the page560 mm×0.7 at 400distance the picture is correct from, shown 160 mm widea rule about the paperwhich is a rule about the reader

Both vanishing points on the paper

Putting the two vanishing points on the sheet is presented as a composition rule. It is a statement about the reader: with the two points one page-width apart the picture is a 90° view, correct from 80 mm, and a reader holding it at arm's length is shown a room five times as deep as the one drawn. The layout that is honest at arm's length puts both points four and a half pages off the sheet.

wrong · Station horizoncorrect from 21 cm, at 160 mm wide6/7 faces · 99% of the surface

A design that lands in two rooms

Cast a design down a corridor with a doorway in it and four per cent of the picture goes through the opening and lands on a wall three metres beyond, at 9.4 metres from the eye against the end wall's 6.4. The picture is continuous across the edge of the doorway and its scale jumps by half again, which is a corner anamorph's discontinuity with a gap in the middle of it instead of a fold.

viewing · Anamorphmap no single viewpoint — the rays miss by no distance at all — the rays are parallel3e-14 px of movement

Nothing moves along the direction

A part slid four metres toward the reader along the direction an isometric drawing projects along keeps its drawn place to a ten-thousandth of a pixel, and the same slide seen from a station point moves it forty-four. An exploded drawing is not an approximation that works because the parts do not move far — it is an identity, and it is why cutaways are drawn in parallel systems.

parallel · Noeye

Named alongside it

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

Affine mapAnamorphosiscentre of projectionCompositioncone of visionContinuityDrawing conventionExploded viewfield of viewFocal lengthForeshorteningKernel

All concepts