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  2. No-three-in-line problem - Wikipedia

    en.wikipedia.org/wiki/No-three-in-line_problem

    The no-three-in-line problem in discrete geometry asks how many points can be placed in the grid so that no three points lie on the same line. The problem concerns lines of all slopes, not only those aligned with the grid. It was introduced by Henry Dudeney in 1900. Brass, Moser, and Pach call it "one of the oldest and most extensively studied ...

  3. United States National Grid - Wikipedia

    en.wikipedia.org/wiki/United_States_National_Grid

    It consists of three parts (each of which follows a "read-right-then-up" paradigm familiar with other "X,Y" coordinates): USNG Grid Zone Designations (CONUS) USNG 100 km Square IDs USNG Grid Coordinates: "Read right, then up" as actual distances (locally, within a 100 km square) Grid Zone Designation (GZD); for a world-wide unique address.

  4. Projected coordinate system - Wikipedia

    en.wikipedia.org/wiki/Projected_coordinate_system

    A projected coordinate system – also called a projected coordinate reference system, planar coordinate system, or grid reference system – is a type of spatial reference system that represents locations on Earth using Cartesian coordinates (x, y) on a planar surface created by a particular map projection. [1]

  5. Alphanumeric grid - Wikipedia

    en.wikipedia.org/wiki/Alphanumeric_grid

    An alphanumeric grid (also known as atlas grid [1]) is a simple coordinate system on a grid in which each cell is identified by a combination of a letter and a number. [ 2 ] An advantage over numeric coordinates such as easting and northing , which use two numbers instead of a number and a letter to refer to a grid cell, is that there can be no ...

  6. Orthogonal coordinates - Wikipedia

    en.wikipedia.org/wiki/Orthogonal_coordinates

    A conformal map acting on a rectangular grid. Note that the orthogonality of the curved grid is retained. While vector operations and physical laws are normally easiest to derive in Cartesian coordinates, non-Cartesian orthogonal coordinates are often used instead for the solution of various problems, especially boundary value problems, such as those arising in field theories of quantum ...

  7. Earth-centered, Earth-fixed coordinate system - Wikipedia

    en.wikipedia.org/wiki/Earth-centered,_Earth...

    The Earth-centered, Earth-fixed coordinate system (acronym ECEF), also known as the geocentric coordinate system, is a cartesian spatial reference system that represents locations in the vicinity of the Earth (including its surface, interior, atmosphere, and surrounding outer space) as X, Y, and Z measurements from its center of mass.

  8. Lambert conformal conic projection - Wikipedia

    en.wikipedia.org/wiki/Lambert_conformal_conic...

    The U.S. National Geodetic Survey's "State Plane Coordinate System of 1983" uses the Lambert conformal conic projection to define the grid-coordinate systems used in several states, primarily those that are elongated west to east such as Tennessee.

  9. Grid (spatial index) - Wikipedia

    en.wikipedia.org/wiki/Grid_(spatial_index)

    Quadtrees are a specialised form of grid in which the resolution of the grid is varied according to the nature and complexity of the data to be fitted, across the 2-d space. Polar grids utilize the polar coordinate system, using circles of a prescribed radius that are divided into sectors of a certain angle. Coordinates are given as the radius ...