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  2. Pyramid (image processing) - Wikipedia

    en.wikipedia.org/wiki/Pyramid_(image_processing)

    A Laplacian pyramid is very similar to a Gaussian pyramid but saves the difference image of the blurred versions between each levels. Only the smallest level is not a difference image to enable reconstruction of the high resolution image using the difference images on higher levels. This technique can be used in image compression. [13]

  3. Crystal system - Wikipedia

    en.wikipedia.org/wiki/Crystal_system

    The hexagonal and trigonal crystal systems differ from the hexagonal and rhombohedral lattice systems. These are combined into the hexagonal crystal family. The relation between three-dimensional crystal families, crystal systems and lattice systems is shown in the following table:

  4. Molecular geometry - Wikipedia

    en.wikipedia.org/wiki/Molecular_geometry

    Trigonal pyramidal: A trigonal pyramidal molecule has a pyramid-like shape with a triangular base. Unlike the linear and trigonal planar shapes but similar to the tetrahedral orientation, pyramidal shapes require three dimensions in order to fully separate the electrons.

  5. Trigonal pyramidal - Wikipedia

    en.wikipedia.org/?title=Trigonal_pyramidal&...

    Download as PDF; Printable version; ... move to sidebar hide. From Wikipedia, the free encyclopedia. Redirect page. ... Trigonal pyramidal molecular geometry ...

  6. Deltahedron - Wikipedia

    en.wikipedia.org/wiki/Deltahedron

    The simplest convex deltahedron is the regular tetrahedron, a pyramid with four equilateral triangles. There are eight convex deltahedra, which can be used in the applications of chemistry as in the polyhedral skeletal electron pair theory and chemical compounds. Omitting the convex property leaves the results in infinitely many deltahedrons ...

  7. Hexagonal crystal family - Wikipedia

    en.wikipedia.org/wiki/Hexagonal_crystal_family

    In particular, there are crystals that have trigonal symmetry but belong to the hexagonal lattice (such as α-quartz). The hexagonal crystal family consists of the 12 point groups such that at least one of their space groups has the hexagonal lattice as underlying lattice, and is the union of the hexagonal crystal system and the trigonal ...

  8. T-shaped molecular geometry - Wikipedia

    en.wikipedia.org/wiki/T-shaped_molecular_geometry

    Ordinarily, three-coordinated compounds adopt trigonal planar or pyramidal geometries. Examples of T-shaped molecules are the halogen trifluorides, such as ClF 3. [1] According to VSEPR theory, T-shaped geometry results when three ligands and two lone pairs of electrons are bonded to the central atom, written in AXE notation as AX 3 E 2.

  9. Crystal structure - Wikipedia

    en.wikipedia.org/wiki/Crystal_structure

    In monoclinic, trigonal, tetragonal, and hexagonal systems there is one unique axis (sometimes called the principal axis) which has higher rotational symmetry than the other two axes. The basal plane is the plane perpendicular to the principal axis in these crystal systems.