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

Multiview — where it appears

The drawing convention of several orthographic views on one sheet, read together by transferring positions between them. The transfer is exact for a vertex of a flat-faced solid and joins two different places on a curved surface, because an outline is not a feature of the object alone.

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

one platethe otherthe hingedrawn at 94.3° · reads as 100.0° or 86.6°an orthographic drawing of a foldtwo readings, 13.4° apart

A drawn fold has a phantom

A Necker cube has two readings and so does a drawn fold, and the fold's second reading is not the supplement of the first. The drawing fixes each plate edge's component in the picture and leaves its component along the ray free up to a sign; a reflection identifies two of the four sign pairs, so there are exactly two plates — and a hundred-degree fold reads as eighty-seven as well.

parallel · foldreversal frontierthe transfer joins points 1.414 R apartone ball, two outlinesmeeting in exactly two points

Two outlines are two curves

The whole method of multiview drawing is the transfer line — a feature at a position in the front view is at the same position along that axis in the top view. On a flat-faced solid the feature is a vertex and the rule is exact. On a ball the two views draw two different great circles, meeting in exactly two points, and the transfer line joins places that are √2 radii apart.

parallel · parallelquadric

Named alongside it

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

DemonstrationDrawing systemOrthographicreconstruction ambiguityContour generatorDepth ambiguityDihedral angleForeshorteningFree parameterFrontier pointOutlineQuadric

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