S2 cells overlay

[xiankai]

Problems observed with old approach:

• Style:
  • Rectangular shape is only relevant near the equator.
  • Nearer to the poles, the cells become increasingly trapezoidal, making the existing style of positioning the cell label/count at the top left become increasingly obsolete.
  • An alternative would be to put a translucent label in the middle of the parallelogram.
• Cell count naming:
  • In larger areas, the old naming convention of A-Z overflows and starts using characters after the ASCII code of Z.
  • Can start to use multiple character sequences (ie. AA1, AB1) or just number everything.
  • S2 unique cell Ids are also a possibility, but less human readable/compact.
  • Track in https://github.com/xiankai/s2-grid
• Cell count area:
  • In larger areas as well, the amount of cells that need to can be too much. This will cause any script to fail.
  • However not all cells are needed. It could be possible to only cover cells for areas with a gym in it.
  • In view of this, the "just number everything" approach to cells makes more sense.