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I'm using GeoTools JTS libraries in Java and I want to find the nearest point inside polygon shape to some single target location. This is exactly what in PostGis ST_ClosestPoint does.

I found this article discussing "Snap a Point to a Line".

So trivial solution will be:

-Dump polygon to lines
-Snap a Point for each above Line
-Calculate the distance between the point and "the snapped" point
-Take the one with minimum distance

How can I achieve my requirement in GeoTools in more "elegant" way?

EDIT:

Actually I'm not sure if the link to snap a point doing exactly what ST_Closest because I don't understand how it's actually extracting the closest point...

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    Convert polygon into MultiLineString and it will be enough to take just one closest point.
    – user30184
    Sep 27, 2015 at 11:09
  • @user30184 You mean with the method in above documentation link? I think this could be an 'answer'...
    – michael
    Sep 27, 2015 at 12:49

1 Answer 1

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JTS's DistanceOP#nearestPoints might be an easy way. I have not tested it.

http://tsusiatsoftware.net/jts/javadoc/com/vividsolutions/jts/operation/distance/DistanceOp.html#nearestPoints%28com.vividsolutions.jts.geom.Geometry,%20com.vividsolutions.jts.geom.Geometry%29

Compute the the nearest points of two geometries. The points are presented in the same order as the input Geometries.

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  • Hi, is there any better performance alternative for DistanceOp? I have fixed set of polygons (let's say 100) and random points (let's say 100.000). I need to find min distance between every point and polygons.
    – Capacytron
    Mar 21, 2018 at 12:57
  • Use a spatial database like PostGIS Mar 26, 2018 at 9:15
  • thanks for your advice, but I have some environment limitations unfortunately, I won't be able to do it.
    – Capacytron
    Mar 27, 2018 at 9:49
  • Then use some spatial index like rtree or something (I am not developing Java anymore, so I do not know). Mar 27, 2018 at 11:33

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