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

Point light — where it appears

A source small enough to be a single centre, which casts a sharp shadow and is the second projection in a lit scene.

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

correct from 26 cm, at 160 mm wide34° across

A shadow is a second projection

The construction that puts a shadow on the ground is the construction that puts the scene on the picture plane, with the lamp where the eye was. Shadow drawing is taught as a separate set of recipes and it is one operation with the centre moved, which is why the same code draws both.

light · shadow 3 m · 18 px6 m · 13 px12 m · 8 pxnear ÷ far = 2.123 against a depth ratio of 2.123exposure 33.3 ms · 6 m/s across the frameeach streak is straight; the set of them is not one kernel

A frame is an interval

An exposure is not an instant, so a frame is an integral of projections and every moving point draws a streak. The streak is straight, because the image of a straight path is straight — and its length goes as one over the depth, so two objects at 3 m and 6 m blur by lengths in the ratio 2.000. No single kernel describes the frame.

sensor · exposure

Named alongside it

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

centre of projectionDemonstrationDepth cueDiminutionForeshorteningHorizoninstrument limitLight footMoving viewpointParallel lightPushbroomResidual

All concepts