Shape

A shape is a graphical representation of an object's form or its external boundary, outline, or external surface; it is distinct from other object properties, such as color, texture, or material type. In geometry, shape excludes information about the object's location, scale, orientation and reflection.^[1] A figure is a representation including both shape and size (as in, e.g., figure of the Earth).

For other uses, see Shape (disambiguation).

A plane shape or plane figure is constrained to lie on a plane, in contrast to solid 3D shapes. A two-dimensional shape or two-dimensional figure (also: 2D shape or 2D figure) may lie on a more general curved surface (a non-Euclidean two-dimensional space).

: Two objects are congruent if one can be transformed into the other by a sequence of rotations, translations, and/or reflections.

Congruence

: Two objects are similar if one can be transformed into the other by a uniform scaling, together with a sequence of rotations, translations, and/or reflections.

Similarity

: Two objects are isotopic if one can be transformed into the other by a sequence of deformations that do not tear the object or put holes in it.

Isotopy

Human perception of shapes[edit]

Human vision relies on a wide range of shape representations.^[7]^[8] Some psychologists have theorized that humans mentally break down images into simple geometric shapes (e.g., cones and spheres) called geons.^[9] Others have suggested shapes are decomposed into features or dimensions that describe the way shapes tend to vary, like their segmentability, compactness and spikiness.^[10] When comparing shape similarity, however, at least 22 independent dimensions are needed to account for the way natural shapes vary. ^[7]

There is also clear evidence that shapes guide human attention.^[11]

Shape

Congruence

Similarity

Isotopy

Human perception of shapes[edit]

Area

Glossary of shapes with metaphorical names

Lists of shapes

Shape factor

Size

Solid geometry

Region (mathematics)

Square