Geotude

A small enough area will become a point. But theoretically, you cannot convert arbitrarily size area into a point. But for convenience and practical purposes; we want a way of referencing a point (lat/lng) to a Geotude, and a Geotude to a point (lat/lng). And to do this, we established that for any Geotude; it is referenced by the point on the North-West (top-left).

Hence, each Geotude (no matter what size/level) can be uniquely identify. Also, all possible lat/lng points that represents Geotude must between 90 ≤ lat < -90 and -180 ≤ lng < 180.

Level-0 Geotude are numbered from left (West) to right (East), and top (North) to bottom (South). This is illustrated from the figure below:

The smallest numbered Geotude is 10000 at lat=-90°, lng=-180°. Geotude number are incremented by 1, when we move from left (West) to right (East). Geotude number are incremented by 500, when we move from top (North) to bottom (South). Hence, the largest numbered Geotude is 99859 at lat=+89°, lng=+179°.