Geometric transformation
In mathematics, a geometric transformation is any bijection of a set to itself (or to another such set) with some salient geometrical underpinning. More specifically, it is a function whose domain and range are sets of points — most often both or both — such that the function is
Classifications
Geometric transformations can be classified by the dimension of their operand sets (thus distinguishing between, say, planar transformations and spatial transformations). They can also be classified according to the properties they preserve:
- Similarities preserve angles and ratios between distances (e.g., resizing);[6]
- collinearity;[8]
Each of these classes contains the previous one.[8]
- circle inversion) preserve the set of all lines and circles, but may interchange lines and circles.
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Original image (based on the map of France)
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Projective transformation
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Inversion
- Conformal transformationspreserve angles, and are, in the first order, similarities.
- Equiareal transformations, preserve areas in the planar case or volumes in the three dimensional case.[9] and are, in the first order, affine transformations of determinant 1.
- Homeomorphisms (bicontinuous transformations) preserve the neighborhoods of points.
- Diffeomorphisms (bidifferentiable transformations) are the transformations that are affine in the first order; they contain the preceding ones as special cases, and can be further refined.
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Conformal transformation
Transformations of the same type form groups that may be sub-groups of other transformation groups.
Opposite group actions
Many geometric transformations are expressed with linear algebra. The bijective linear transformations are elements of a
The transpose of a row vector v is a column vector vT, and the transpose of the above equality is Here AT provides a left action on column vectors.
In transformation geometry there are compositions AB. Starting with a row vector v, the right action of the composed transformation is w = vAB. After transposition,
Thus for AB the associated left group action is In the study of
See also
- Coordinate transformation
- Erlangen program
- Symmetry (geometry)
- Motion
- Reflection
- Rigid transformation
- Rotation
- Topology
- Transformation matrix
References
- OCLC 50004269.
- ISBN 9780131437005
- ^ "Geometry Translation". www.mathsisfun.com. Retrieved 2020-05-02.
- ^ "Geometric Transformations — Euclidean Transformations". pages.mtu.edu. Retrieved 2020-05-02.
- ^ a b Geometric transformation, p. 131, at Google Books
- ^ "Transformations". www.mathsisfun.com. Retrieved 2020-05-02.
- ^ "Geometric Transformations — Affine Transformations". pages.mtu.edu. Retrieved 2020-05-02.
- ^ a b Leland Wilkinson, D. Wills, D. Rope, A. Norton, R. Dubbs – 'Geometric transformation, p. 182, at Google Books
- ^ Geometric transformation, p. 191, at Google Books Bruce E. Meserve – Fundamental Concepts of Geometry, page 191.]
Further reading
- ISBN 978-0-486-49851-5
- Dienes, Z. P.; Golding, E. W. (1967) . Geometry Through Transformations (3 vols.): Geometry of Distortion, Geometry of Congruence, and Groups and Coordinates. New York: Herder and Herder.
- David Gans – Transformations and geometries.
- ISBN 0-8284-1087-9.
- John McCleary (2013) Geometry from a Differentiable Viewpoint, ISBN 978-0-521-11607-7
- Modenov, P. S.; Parkhomenko, A. S. (1965) . Geometric Transformations (2 vols.): Euclidean and Affine Transformations, and Projective Transformations. New York: Academic Press.
- A. N. Pressley – Elementary Differential Geometry.
- Yaglom, I. M. (1962, 1968, 1973, 2009) . Geometric Transformations (4 vols.). Random House (I, II & III), MAA (I, II, III & IV).