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If the point is latitude X, longtiude Y, we compute geohashes for the following points:
N: X, Y+1e-04
NE: X+7e-05, Y+7e-05
E: X+1e-04, Y
SE: X+7e-05, Y-7e-05
S: X, Y-1e-04
SW: X-7e-05, Y-7e-05
W: X-1e-04, Y
NW: NE: X-7e-05, Y+7e-05
This is approximately a circle of radius 10m, using an approximate that 1e-05 degrees is 1m. In fact it is 1.1m of longitude and 1.1m to 0.7m of latitude (from the equator to 50 degrees north). Given the overall crudeness of geohash accuracy, and inaccuracy inherent in our GPS position, we consider this “good enough” for MVP1.
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