Varna Plan is an impressive Google Maps mash-up for the Varna area in Bulgaria. Thanks to the map's impressive area polygon selection search engine it is possible to view an incredible amount of data about Varna on the map.
It is possible to view commercial, rental and residential property for sale in Varna. It is also possible to view from a large selection of tourist related layers.
Varna Plan does some amazing processing to calculate whether points are within a defined area. It can actually carry out between 25 to 400 million record comparisons a second. Varna Plan can search within complex non-regular polygons on the map by reducing them to a series of regular polygons.
It does this by creating a virtual grid in memory using squares of the desired accuracy. It uses the graphics rendering tools available in java to create an image in memory, map it onto the squares and then check to see if the chosen point is within one of the squares. If the shapes are fixed then some of this can be done before the request and stored.