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

Coverage — where it appears

How much of an object a design actually lands on, reported as the share of the design that finds it, the faces that receive anything, and the area those faces are. The three differ: a face is reached when it receives one mark, so a count of faces and a share of area answer different questions.

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

no single viewpoint — the rays miss by no distance at all — the rays are parallel13 of 21 faces

A picture with no eye

The anamorph field measured which parts of an object one eye can paint, and every finding in it is about a point. A parallel projection has no such point, so the same questions have a different shape — and the two that change are the dimension of the answer and the map onto each face. The one that does not change is occlusion, which is routinely assumed away.

parallel · Noeye no single viewpoint — the rays miss by no distance at all — the rays are parallel4 pictures on 3 kinds of face

A flight that has ends

A real staircase has three families of faces and the rule proposed last round predicted three pictures. It supports four, because a picture is fixed by a direction and the flight's two sides point opposite ways — one kind of face that no single direction reaches both of. The rule counts words and the object counts orientations.

viewing · Anamorphreach column 62 mmcorrect from 19 cm, at 160 mm wide0.966% hidden, to 15.3° from the nadir

The hole a rig cannot fill

A two-lens spherical rig covers every direction between its two lenses and still cannot see 0.470 per cent of the sphere directly beneath it, reaching 12.8 degrees from straight down — its own tripod, standing exactly where neither lens can look. No arrangement of lenses removes it, because it is not a gap in coverage; it is the rig occluding itself.

curved · Nadir

Named alongside it

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

OcclusionAnamorphosiscentre of projectionDesign planeFaceted objectParallel projectionAffine mapCountingDisjoint setsEntrance pupilNodal pointPanorama

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