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Page history last edited by Tantek 3 years, 3 months ago

Octal Geo Coordinate System


A simple geo location system based on octal coordinates to enable geo short URLs with increasing precision character by character, by compressing each octal latitude and longitude digit into a single base 64 character.


(stub article)




  • convert traditional lat long decimal degrees to octal values
    • latitude -90 to 90 to decimal [-128.0,128.0], octal [-0200.0,0200.0]
    • longitude -180 to 180 to decimal [-256.0,256.0), octal [-0400.0,0400.0)
  • encode in NewBase64
  • result: increasing precision based on an 8x8 64 square grid for each digit 


non-negative variant 2019-02-12

  • find a way to drop use of negative values, in order to increase data fidelity in practice (avoid negative value "corrections" as experienced with meta icbn / geourl tags as historically noted). inspired by this today: https://github.com/indieweb/2019.indieweb.org/pull/12.
  • attempt to preserve 0,0:
    • longitude 0 to 180 to decimal [0,256.0), octal [0,0400.0)
    • longitude -180 to 0 to decimal [256.0,512.0), octal [0400.0,1000.0)
    • latitude is harder translate contiguously while maintaining 0 at equator due to need for both -90 and +90, as well as no "wraparound"
  • or reset 0,0 to southpole antimeridian (just as https://en.wikipedia.org/wiki/Open_Location_Code did)
    • latitude -90 to 90 to decimal [0,256.0], octal [0,0400.0]
    • longitude -180 to 180 to decimal [0,512.0), octal [0,1000.0) (or inclusive [0,777.7̅])




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