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Ptolemy's map of the Mediterranean superimposed on a modern map, with Greenwich as the reference longitude. Ptolemy, in the 2nd century AD, based his mapping system on estimated distances and directions reported by travellers. Until then, all maps had used a rectangular grid with latitude and longitude as straight lines intersecting at right ...
Geodetic latitude and geocentric latitude have different definitions. Geodetic latitude is defined as the angle between the equatorial plane and the surface normal at a point on the ellipsoid, whereas geocentric latitude is defined as the angle between the equatorial plane and a radial line connecting the centre of the ellipsoid to a point on the surface (see figure).
Figure 1. This BLM map depicts the principal meridians and baselines used for surveying states (colored) in the PLSS. The following are the principal and guide meridians and base lines of the United States, with the year established and a brief summary of what areas' land surveys are based on each.
This is an accepted version of this page This is the latest accepted revision, reviewed on 1 March 2025. System to specify locations on Earth For broader coverage of this topic, see Spatial reference system. Longitude lines are perpendicular to and latitude lines are parallel to the Equator. Geodesy Fundamentals Geodesy Geodynamics Geomatics History Concepts Geographical distance Geoid Figure ...
Some old maps in the Mercator projection have grids composed of lines of latitude and longitude but also show rhumb lines which are oriented directly towards north, at a right angle from the north, or at some angle from the north which is some simple rational fraction of a right angle. These rhumb lines would be drawn so that they would ...
Lines of longitude appear vertical with varying curvature in this projection, but are actually halves of great ellipses, with identical radii at a given latitude. Latitude (φ) Lines of latitude appear horizontal with varying curvature in this projection; but are actually circular with different radii. All locations with a given latitude are ...
Equirectangular projection of the world; the standard parallel is the equator (plate carrée projection). Equirectangular projection with Tissot's indicatrix of deformation and with the standard parallels lying on the equator True-colour satellite image of Earth in equirectangular projection Height map of planet Earth at 2km per pixel, including oceanic bathymetry information, normalized as 8 ...
The figure below shows a point P at latitude φ and longitude λ on the globe and a nearby point Q at latitude φ + δφ and longitude λ + δλ. The vertical lines PK and MQ are arcs of meridians of length Rδφ. [d] The horizontal lines PM and KQ are arcs of parallels of length R(cos φ)δλ.