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

Rabatment — where it appears

Folding a plane about the line it shares with another until the two lie flat together, which is how a perspective construction gets both planes into one drawing.

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

floorpicture planeeye level — no mark above thiseye · 1.62 m up, 2.40 m backthe ground line, seen from abovethe mark runs to 3.00 ma point 1.62 m up casts no mark at all

A floor anamorph is three numbers

An anamorph is described everywhere as a picture stretched until only one viewpoint can read it, which says what it looks like and nothing about what it is. Cast one onto a floor and fit a map to the marks, and the map turns out to be a planar homology — a line of fixed points, one point off it, and a single ratio. Those three numbers are not a description of the eye. They are the eye.

viewing · anamorphmap axis — the ground line, fixed pointwisecentreaxisthe ground linefixed pointwisecentre(0.150, 4.020)height + distanceratio-1.481481−distance / heightheight × aspect = 2.592, and neither aloneeye recovered to 4.8e-12 mmeye 1.62 m up, 2.40 m backthree numbers back to the eye: 2.2e-16 m

The marks name the place, not the height

Run the site's own round trip on an anamorph — hand the machinery the floor marks and ask for the eye back — and it returns the spot on the floor to eleven decimal places with nothing assumed at all. It does not return the height. What the marks fix is the product of the eye's height with the design's aspect ratio, and no amount of looking at the floor separates the two.

viewing · anamorphrecovery

Named alongside it

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

AnamorphosisCharacteristic ratioDemonstrationFixed pointPlanar homologyStation pointCentral collineationCollineationConditioningdegrees of freedomDistance pointFree parameter

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