Add concave hull method to Geometry.

Author: jericks

src/main/groovy/geoscript/geom/Geometry.groovy

@@ -2,6 +2,7 @@ package geoscript.geom
 
 import org.locationtech.jts.algorithm.construct.LargestEmptyCircle
 import org.locationtech.jts.algorithm.construct.MaximumInscribedCircle
+import org.locationtech.jts.algorithm.hull.ConcaveHull
 import org.locationtech.jts.geom.Geometry as JtsGeometry
 import org.locationtech.jts.geom.GeometryFactory
 import org.locationtech.jts.geom.Coordinate
@@ -134,6 +135,15 @@ class Geometry {
         wrap(g.convexHull())
     }
 
+    /**
+     * Calculate the concave hull
+     * @param maxLength The max length
+     * @return A Geometry
+     */
+    Geometry concaveHull(double maxLength = 0.0) {
+        wrap(ConcaveHull.concaveHullByLength(g, maxLength))
+    }
+
     /**
      * Whether this Geometry is covered by the other Geometry
      * @param The other Geometry

src/test/groovy/geoscript/geom/GeometryTest.groovy

@@ -737,8 +737,30 @@ geometry:
                 new Point(-90.7031, 34.016)
         )
         Geometry convexHull = geometry.convexHull
-        assertEquals("POLYGON ((-90.7031 34.016, -111.796 42.553, -119.882 47.279, " +
-                "-100.195 46.316, -90.7031 34.016))", convexHull.wkt)
+        assertEquals("POLYGON ((-122.3876953125 47.58121554959838, -122.39078521728516 47.58167872046887, " +
+                "-122.3876953125 47.5828366297174, -122.38657951354979 47.58451555263637, " +
+                "-122.38494873046875 47.58301031389572, -122.38177299499512 47.5823155737249, " +
+                "-122.38486289978027 47.5812734461813, -122.38649368286131 47.5772205307505, " +
+                "-122.3876953125 47.58121554959838))", convexHull.wkt)
+    }
+
+    @Test void concaveHull() {
+        Geometry geometry = Geometry.fromWKT("MULTIPOINT (" +
+            "(-122.38657951354979 47.58451555263637), "+
+            "(-122.38649368286131 47.5772205307505), "+
+            "(-122.39078521728516 47.58167872046887), "+
+            "(-122.38177299499512 47.5823155737249), "+
+            "(-122.3876953125 47.5828366297174), "+
+            "(-122.38494873046875 47.58301031389572), "+
+            "(-122.3876953125 47.58121554959838), "+
+            "(-122.38486289978027 47.5812734461813)"+
+            ")")
+        Geometry concaveHull = geometry.concaveHull()
+        assertEquals("POLYGON ((-122.3876953125 47.58121554959838, -122.39078521728516 47.58167872046887, " +
+                "-122.3876953125 47.5828366297174, -122.38657951354979 47.58451555263637, " +
+                "-122.38494873046875 47.58301031389572, -122.38177299499512 47.5823155737249, " +
+                "-122.38486289978027 47.5812734461813, -122.38649368286131 47.5772205307505, " +
+                "-122.3876953125 47.58121554959838))", concaveHull.wkt)
     }
 
     @Test void covers() {