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

Catoptric — where it appears

Formed by reflection — a picture whose rays reached the eye off a mirror rather than directly. The mirror is a second camera when it is flat and a projection from nowhere when it is curved, so the two cases need entirely different machinery.

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

eye, 74° offgrey: the word before the projectionblack: the same word, projected

Anamorphosis is only a viewpoint

A smear on a wall that resolves into a skull when the viewer stands in one particular place off to the side. It is not a trick added to perspective — it is perspective, with the centre of projection put somewhere nobody would naturally stand, and it is the clearest demonstration there is that every picture has such a point.

viewing · Anamorph the sheet, seen from abovemirrorthe eye, 2.4 radii upwhat stands up in the mirrorthe light path reverses to the eye to 1e-15scale varies 7.2× across the design

The cylindrical mirror unbends it

Put a mirrored cylinder in the middle of the sheet and the light path from the eye to the paper bends once. The map that results is not a homography and not a projection in the plane sense at all — it varies its scale by a factor of seven across the design, which is why the smear is unreadable and why the mirror can put it back.

viewing · Anamorph

Named alongside it

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

AnamorphosisArea scaleAzimuthCatoptric anamorphosisCylindrical mirrorHomographyLight pathOblique projectionRectificationReflection

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