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

Depth from disparity — where it appears

Depth recovered from how far a point shifts between two views, which is the baseline times the focal length over the distance. Because it is a reciprocal, a fixed error in the picture maps to an interval in the world that is not symmetric and eventually is not bounded.

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

020406012345the baseline between the two eyes (metres)angle between the cone axes (°)42.6°two cones, one ballcentre to 9e-7°

Two pictures of a ball

Two outlines give two tangent cones, and where their axes cross is the ball's centre — with the radius following from either half-angle. There is no correspondence problem, because a ball's outline in one picture and its outline in another are guaranteed to be the same ball; and there is a degeneracy, which is the two eyes and the ball in a line, and the solver refuses it rather than returning something plausible.

metrology · ballrecovery -500500.5001distance to the thing being stitched (log₁₀ metres)what the stitch leaves behind (px)2.86 m80 mm baselinezero at one depth each

A rig is right on one surface

Several cameras looking outward have several centres, and no warp registers all of a scene. The residual is a disparity, so the depth the stitch is computed for has an exact optimum — the harmonic midpoint of the depth range, not the middle of it — and the arithmetic middle costs a factor of 2 z_far over the sum, which tends to two.

curved · stitchdepth

Named alongside it

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

BaselineDemonstrationAngular sizeCalibrationcentre of projectionConditioningDisparityEpipolar geometryleast-squares intersectionMinimaxPanoramaParallax

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