MongoDB 3.0 introduces the Big Polygon feature, which allows searching polygons larger than half the Earth's surface. This new feature addresses the issue of geospatial queries yielding incorrect results when dealing with large polygons that span more than half of the Earth's surface. To overcome this limitation, MongoDB now supports a custom coordinate reference system (CRS) that forces geospatial queries to consider the direction of coordinates in deciding upon an inclusive or exclusive area. The CRS can be specified on any geometry object via a `crs` property, and currently only supports strict winding behavior. This feature is particularly useful for searching areas that are larger than half of the Earth's surface, such as the example of a circle centred around 25°N, 90°E with a diameter of 115°. By specifying a custom CRS, users can ensure that their geospatial queries yield accurate results in these cases.