singhbaljit commented on a change in pull request #97:
URL: https://github.com/apache/commons-geometry/pull/97#discussion_r454081205
##########
File path:
commons-geometry-spherical/src/test/java/org/apache/commons/geometry/spherical/twod/RegionBSPTree2STest.java
##########
@@ -838,6 +843,48 @@ public void testCircleToPolygonBoundarySize() {
Assert.assertEquals("Clockwise boundary size", boundary,
cw.getBoundarySize(), 1.0e-7);
}
+ @Test
+ public void testSmallCircleToPolygon() {
+ // arrange
+ final double radius = 5.0e-8;
+ final Point2S center = Point2S.of(0.5, 1.5);
+ final int numPts = 100;
+
+ // act
+ final RegionBSPTree2S circle = circleToPolygon(center, radius, numPts,
false);
+
+ // assert
+ // https://en.wikipedia.org/wiki/Spherical_cap
+ final double area = 4.0 * PlaneAngleRadians.PI *
Math.pow(Math.sin(radius / 2.0), 2.0);
+ final double boundary = PlaneAngleRadians.TWO_PI * Math.sin(radius);
+
+ SphericalTestUtils.assertPointsEq(center, circle.getCentroid(),
TEST_EPS);
+ Assert.assertEquals(area, circle.getSize(), TEST_EPS);
+ Assert.assertEquals(boundary, circle.getBoundarySize(), TEST_EPS);
+ }
+
+ @Test
+ public void testSmallGeographicalRectangle() {
+ // arrange
+ final double[][] vertices = {
+ {42.656216727628696, -70.61919768884546},
+ {42.65612858998112, -70.61938607250165},
+ {42.65579098923594, -70.61909615581666},
+ {42.655879126692355, -70.61890777301083}
+ };
+
+ // act
+ final RegionBSPTree2S rectangle = latLongToTree(TEST_PRECISION,
vertices);
+
+ // assert
+ // approximate the centroid as average of vertices
+ final double avgLat = Stream.of(vertices).mapToDouble(v ->
v[0]).average().getAsDouble();
+ final double avgLon = Stream.of(vertices).mapToDouble(v ->
v[1]).average().getAsDouble();
+ final Point2S centroid = latLongToPoint(avgLat, avgLon);
+
+ SphericalTestUtils.assertPointsEq(centroid, rectangle.getCentroid(),
TEST_EPS);
Review comment:
Thoughts on using [GeographicLib](https://geographiclib.sourceforge.io)
as reference? Using flattening of `0` means perfect sphere.
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