public void Test_S2LatLngRect_GetDirectHausdorffDistancePointToRect()
{
// The Hausdorff distance from a point to a rect should be the same as its
// distance to the rect.
S2LatLngRect a1 = PointRectFromDegrees(5, 8);
S2LatLngRect a2 = PointRectFromDegrees(90, 10); // north pole
S2LatLngRect b = RectFromDegrees(-85, -50, -80, 10);
Assert2.DoubleEqual(a1.GetDirectedHausdorffDistance(b).Radians,
a1.GetDistance(b).Radians);
Assert2.DoubleEqual(a2.GetDirectedHausdorffDistance(b).Radians,
a2.GetDistance(b).Radians);
b = RectFromDegrees(4, -10, 80, 10);
Assert2.DoubleEqual(a1.GetDirectedHausdorffDistance(b).Radians,
a1.GetDistance(b).Radians);
Assert2.DoubleEqual(a2.GetDirectedHausdorffDistance(b).Radians,
a2.GetDistance(b).Radians);
b = RectFromDegrees(70, 170, 80, -170);
Assert2.DoubleEqual(a1.GetDirectedHausdorffDistance(b).Radians,
a1.GetDistance(b).Radians);
Assert2.DoubleEqual(a2.GetDirectedHausdorffDistance(b).Radians,
a2.GetDistance(b).Radians);
}
public void Test_S2LatLngRect_GetDirectedHausdorffDistanceContained()
{
// Caller rect is contained in callee rect. Should return 0.
S2LatLngRect a = RectFromDegrees(-10, 20, -5, 90);
Assert.Equal(S1Angle.FromRadians(0),
a.GetDirectedHausdorffDistance(RectFromDegrees(-10, 20, -5, 90)));
Assert.Equal(S1Angle.FromRadians(0),
a.GetDirectedHausdorffDistance(RectFromDegrees(-10, 19, -5, 91)));
Assert.Equal(S1Angle.FromRadians(0),
a.GetDirectedHausdorffDistance(RectFromDegrees(-11, 20, -4, 90)));
Assert.Equal(S1Angle.FromRadians(0),
a.GetDirectedHausdorffDistance(RectFromDegrees(-11, 19, -4, 91)));
}
// This function assumes that GetDirectedHausdorffDistance() always returns
// a distance from some point in a to b. So the function mainly tests whether
// the returned distance is large enough, and only does a weak test on whether
// it is small enough.
private static void VerifyGetDirectedHausdorffDistance(S2LatLngRect a, S2LatLngRect b)
{
S1Angle hausdorff_distance = a.GetDirectedHausdorffDistance(b);
const double kResolution = 0.1;
S1Angle max_distance = S1Angle.Zero;
int sample_size_on_lat =
(int)(a.Lat.GetLength() / kResolution) + 1;
int sample_size_on_lng =
(int)(a.Lng.GetLength() / kResolution) + 1;
double delta_on_lat = a.Lat.GetLength() / sample_size_on_lat;
double delta_on_lng = a.Lng.GetLength() / sample_size_on_lng;
double lng = a.Lng.Lo;
for (int i = 0; i <= sample_size_on_lng; ++i, lng += delta_on_lng)
{
double lat = a.Lat.Lo;
for (int j = 0; j <= sample_size_on_lat; ++j, lat += delta_on_lat)
{
S2LatLng latlng = S2LatLng.FromRadians(lat, lng).Normalized();
S1Angle distance_to_b = b.GetDistance(latlng);
if (distance_to_b >= max_distance)
{
max_distance = distance_to_b;
}
}
}
Assert.True(max_distance.Radians <= hausdorff_distance.Radians + 1e-10);
Assert.True(max_distance.Radians >= hausdorff_distance.Radians - kResolution);
}
