To use the
$centeroperator, specify an array that contains:
- The grid coordinates of the circle’s center point, and
- The circle’s radius, as measured in the units used by the coordinate system.
If you use longitude and latitude, specify longitude first.
The query calculates distances using flat (planar) geometry.
Applications can use
$center without having a geospatial index. However, geospatial indexes support much faster queries than the unindexed equivalents.