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

rectified pair — where it appears

Two pictures brought to coplanar image planes, so a point's match lies on the same row and the search is one-dimensional.

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

025507510010203040true depth (m)depth reported from the disparity, with a 1 px reading error5.86–7.33 m13.96–26.69 m23.76–126.49 mat 40 m: +86.5 m against −16.2 munbounded past 58.5 m

Depth is a reciprocal

Two eyes measure a shift in the picture, and depth is that shift divided into a constant. So a fixed error in what is read maps to an interval in what is reported that is not centred on the answer, and at forty metres runs sixteen metres nearer and eighty-six further.

depth · disparity 123-2-10baseline (m, log scale)range past which 1 px of disparity error is unbounded (m, log scale)65 mm → 58.5 mrange = fB/δ — 58.5 m at a 65 mm baseline900 px focal length, 1 px reading

The range a pair cannot see past

A stereo rig has a distance beyond which it cannot say "no further than", and the distance is fixed before anything is built. It is the focal length times the baseline divided by the reading precision, and for a human pair of eyes it is fifty-eight and a half metres.

depth · disparity

Named alongside it

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

BaselineDepth uncertaintyDisparityFocal lengtherror propagationinstrument limitReference lengthTriangulation

All concepts