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

Normalisation — where it appears

Fixing what a measurement is quoted against, so that the things being compared differ only in what is being asked. Holding a mark budget rather than a focal length is what makes a comparison of picture surfaces about distribution instead of about image size.

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

0.5120.1110100how finely each point is read off the picture (px, log scale)worst epipolar error against the exact geometry (px, log scale)raw pixelscentred and scaled1.1× apart at 0.25 px, 29.9× at 4 pxspread 102 against 2.5e+5

Eight points and the basis they are read in

The linear system that recovers a fundamental matrix is written in whatever coordinates the marks were read in, and pixel coordinates are a bad choice. Centring and scaling them first is worth nothing at a quarter-pixel reading and a factor of thirty at four.

twoviews · Eightpoint 87.7% of the skycorrect from 16 cm, at 160 mm wide5.512 sr of 6.283

What a point in shadow can see of the sky

A place directly under a slab is not sealed off from the sky at all — it sees 83.4 per cent of it, 5.242 of the 6.283 steradians a place in the open has, against 5.240 from the closed form for a rectangle's own solid angle. The same counted-directions call that measures a lamp's penumbra measures this fraction too, and the two agree to 2.50e-4 with the source simply swapped from a lamp to the whole sky.

light · Ambient

Named alongside it

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

BaselineConditioningCorrespondencedesign matrixeight-point algorithmFundamental matrixPenumbraPoint sourceRadianceShadow projectionsingular valuesSolid angle

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