Geospatial Queries with Google App Engine using GeoModel - Google Maps API Family - Google Code
►http://code.google.com/intl/fr/apis/maps/articles/geospatial.html#geospatial
super les #algorithmes de #geopositionnement
Geocells
In #GeoModel a #geocell is labeled by a hexadecimal string that defines a two dimensional rectangular region inside the [-90,90] x [-180,180] latitude/longitude space. Resolution of a geocell is measured by the length of its string label. We start out with 16 geocells labeled by hexdecimal number with a single digit and subsequently divide each geocell into 16 more geocells labeled by hexdecimal strings with more digits.