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Geospatial

H3

Interesting

  • The U.S. Is Getting Shorter, as Mapmakers Race to Keep Up
  • 'Gravity matters to a geodesist. Height is distance measured along the direction that gravity points, and the strength and direction of gravity’s pull vary according to the density of what is beneath the terrain and near it. In other words, height is not merely distance or elevation above the ground; it is tied to gravity. Gravity, in turn, is related to the distribution of mass. Geodesists therefore use the term “height” rather than “elevation.”'
  • Bending Lines: Maps and Data From Distortion to Deception

Slippy Maps

  • Planet: Slippy Maps 101
  • A core component of Slippy Maps is that the images should be served as tiles on a grid. Tiling images is an efficient way to browse large amounts of raster and vector map data that would be much too large to render as a single map image.
  • At zoom level 0, an entire mercator projection of the earth is contained in one 256px by 256px tile
  • At each further zoom level the number of tiles increases by a factor of four and the spatial resolution (ground meters per pixel) of each tile roughly doubles.
  • At any given zoom level, a specific tile can be identified by cartesian coordinates with 0,0 starting in the top left of the map.
  • Why tiled maps?
  • A Web Map from Scratch

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