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Find if a geographical point lies within a set of points making a polygon

Given a set of geographical coordinates making up a polygon, how would I determine if another geographical point (x-latitude, y-longitude) lies either within the polygon, or outside the polygon. The set of coordinates is stored in a table in an SQL server database.

Paul 1

The first process is to create a virtual box around the polygon. This gives you a top, bottom, left and right value to see if the target point is close ( T > bottom, T < Top, T > Left and T < Right)

If the value is confirmed then you work out the 3 nearest point to form a triangle and then calculate - check this to see the theory - http://www.blackpawn.com/texts/pointinpoly/

also this explains - http://stackoverflow.com/questions/2049582/how-to-determine-a-point-in-a-triangle

gurutc

Are you using LatLon, UTM, UPS, MGRS, MGRS Polar, USNG (identical to MGRS), Georef, or State Plane coordinate systems? Depending on the coordinate format, it'll be an algebraic equation.

- gurutc

gurutc

Also, what type of polygon? How many points?

SOLUTION