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  2. Alhazen's problem - Wikipedia

    en.wikipedia.org/wiki/Alhazen's_problem

    They showed that the mirror reflection point can be computed by solving an eighth degree equation in the most general case. If the camera (eye) is placed on the axis of the mirror, the degree of the equation reduces to six. [15] Alhazen's problem can also be extended to multiple refractions from a spherical ball.

  3. Reflection (mathematics) - Wikipedia

    en.wikipedia.org/wiki/Reflection_(mathematics)

    Point Q is the reflection of point P through the line AB. In a plane (or, respectively, 3-dimensional) geometry, to find the reflection of a point drop a perpendicular from the point to the line (plane) used for reflection, and extend it the same distance on the other side. To find the reflection of a figure, reflect each point in the figure.

  4. Dihedral symmetry in three dimensions - Wikipedia

    en.wikipedia.org/wiki/Dihedral_symmetry_in_three...

    D 1h and C 2v: group of order 4 with a reflection in a plane and a 180° rotation about a line in that plane. D 1d and C 2h: group of order 4 with a reflection in a plane and a 180° rotation about a line perpendicular to that plane. For n = 2 there is not one main axis and two additional axes, but there are three equivalent ones.

  5. Symmetry - Wikipedia

    en.wikipedia.org/wiki/Symmetry

    An object has reflectional symmetry (line or mirror symmetry) if there is a line (or in 3D a plane) going through it which divides it into two pieces that are mirror images of each other. [6] An object has rotational symmetry if the object can be rotated about a fixed point (or in 3D about a line) without changing the overall shape. [7]

  6. Rotations and reflections in two dimensions - Wikipedia

    en.wikipedia.org/wiki/Rotations_and_reflections...

    The set of all reflections in lines through the origin and rotations about the origin, together with the operation of composition of reflections and rotations, forms a group. The group has an identity: Rot(0). Every rotation Rot(φ) has an inverse Rot(−φ). Every reflection Ref(θ) is its own inverse. Composition has closure and is ...

  7. Mirror image - Wikipedia

    en.wikipedia.org/wiki/Mirror_image

    In geometry, the mirror image of an object or two-dimensional figure is the virtual image formed by reflection in a plane mirror; it is of the same size as the original object, yet different, unless the object or figure has reflection symmetry (also known as a P-symmetry).

  8. Icosahedral symmetry - Wikipedia

    en.wikipedia.org/wiki/Icosahedral_symmetry

    The edges of a spherical compound of five octahedra represent the 15 mirror planes as colored great circles. Each octahedron can represent 3 orthogonal mirror planes by its edges. The pyritohedral symmetry is an index 5 subgroup of icosahedral symmetry, with 3 orthogonal green reflection lines and 8 red order-3 gyration points. There are 5 ...

  9. Geometrical optics - Wikipedia

    en.wikipedia.org/wiki/Geometrical_optics

    In particular, spherical mirrors exhibit spherical aberration. Curved mirrors can form images with magnification greater than or less than one, and the image can be upright or inverted. An upright image formed by reflection in a mirror is always virtual, while an inverted image is real and can be projected onto a screen. [3]