How to determine which Geocoordinates are inside a defined Area?

my Application is given a list of Geocorrdinates and now I have to determine which of those Coordinates are inside a defined Area. For example the Search would definiton would be: Show me all Areas where 100 Coordinates are in an Area of 1km^2. So I have to find out which of thes开发者_如何学JAVAe coordinates are together in Areas of 1km^2 and more than 100. But that seems to be a hard Job for my understanding of geocoordinates and I hope someone can help me with that.

The Latitude coordinates are consistent and Distance between two degrees is 111km. For example the Distance between N50,985° and N50,995° is 1,11km. The Distance between 2 Longtitude Coordinates is not so easy and depends on the Latitude coordinate. But to be honest, I really don't know how to start.

Does someone have an Idea and can help me?

Thank you

twickl

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what you need is a geospatial database, I'd recommend PostgreSQL with PostGIS. It provides the function you need to calculate this kind of stuff. Also search for good tutorials about it. An example is a radius search like "give me all McDonalds in a radius of 10km where I live"

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If the problem with having a database is simply that you don't want to host it (or pay for someone to host it) then I recommend Fusion Tables.

I don't know if it supports exactly the functionality you are looking for, however I suppose you could select a random point and do a count of everything within range of that point.

I think that what you are talking could be quite a cpu intensive task (depending on how accurate you want it to be). Not something I would personally try and unload onto a portable device.