jiayuasu commented on code in PR #2863:
URL: https://github.com/apache/sedona/pull/2863#discussion_r3144487263
##########
common/src/test/java/org/apache/sedona/common/FunctionsTest.java:
##########
@@ -1081,6 +1081,181 @@ public void testS2ToGeom() {
assertTrue(polygons[100].intersects(target));
}
+ @Test
+ public void testS2CoverageContainsInput() throws ParseException {
+ String wkt =
+ "POLYGON ((-102.060778 39.9999603, -102.0535384 40.0119065, -101.98532
40.0122906, "
+ + "-95.30829 40.009008, -95.2456364 39.9564784, -95.1982467
39.9455019, "
+ + "-95.1964657 39.9113444, -95.1460439 39.9142017, -95.1316877
39.8855881, "
+ + "-95.087643 39.8717975, -95.0389987 39.8749063, -95.0146232
39.9088422, "
+ + "-94.9403146 39.906409, -94.9183761 39.8846514, -94.9329504
39.8578468, "
+ + "-94.8824331 39.8409102, -94.8675709 39.8227528, -94.878404
39.787242, "
+ + "-94.9266292 39.7786779, -94.9070076 39.7679231, -94.8631596
39.779774, "
+ + "-94.8497103 39.7604914, -94.8545514 39.7397163, -94.8985678
39.7150641, "
+ + "-94.9584897 39.7331377, -94.9637588 39.6814526, -95.0187723
39.6615712, "
+ + "-95.0456083 39.6252182, -95.0430365 39.5826542, -95.0650104
39.5677387, "
+ + "-95.0985514 39.570063, -95.1012286 39.5462821, -95.0459187
39.5064755, "
+ + "-95.0320969 39.4709074, -94.976457 39.4475392, -94.9362514
39.3964717, "
+ + "-94.8781205 39.3949417, -94.8733156 39.3663291, -94.9014695
39.3495654, "
+ + "-94.8963639 39.3135051, -94.8237994 39.2609956, -94.8194328
39.2178517, "
+ + "-94.7789019 39.214907, -94.7398645 39.1789812, -94.6785238
39.1931279, "
+ + "-94.6533801 39.1816662, -94.6517728 39.1640754, -94.605515
39.1696807, "
+ + "-94.5791896 39.1504025, -94.5983384 39.1134256, -94.6095667
36.9948123, "
+ + "-102.045765 36.9847897, -102.060778 39.9999603))";
+ Geometry input = geomFromWKT(wkt, 0);
+ Long[] cellIds = Functions.s2CellIDs(input, 12);
+ Geometry[] polygons =
+
Functions.s2ToGeom(Arrays.stream(cellIds).mapToLong(Long::longValue).toArray());
+ Geometry coverage = Functions.union(polygons);
+ if (!coverage.covers(input)) {
+ // The union above is unavoidable for an exact containment check; we
additionally
+ // skip the (expensive, ~50k-cell) difference on the happy path and only
compute it
+ // on failure to surface a useful diagnostic.
+ Geometry uncovered = input.difference(coverage);
+ double uncoveredArea = uncovered.getArea();
+ fail(
+ String.format(
+ "Coverage does not contain input. Missing %.8f deg^2 (%.6f%%)",
+ uncoveredArea, (uncoveredArea / input.getArea()) * 100.0));
+ }
+ }
+
+ @Test
+ public void testS2CoverageContainsLineString() throws ParseException {
+ // Long east-west line at mid-latitude. The great-circle arc bulges
poleward of the JTS
+ // chord, so before the buffer fix the cells along the parallel were
missed in the middle.
+ Geometry line = geomFromWKT("LINESTRING (-102 37, -94 37)", 0);
+ Long[] cellIds = Functions.s2CellIDs(line, 12);
+ Geometry[] cells =
+
Functions.s2ToGeom(Arrays.stream(cellIds).mapToLong(Long::longValue).toArray());
+ Geometry coverage = Functions.union(cells);
+ assertTrue(
+ "S2 cell coverage of LineString does not contain the line itself.",
coverage.covers(line));
+ }
+
+ @Test
+ public void testS2CoverageContainsMultiPolygon() throws ParseException {
+ // Two disjoint polygons, both at mid-northern latitude with long
east-west edges.
+ String wkt =
+ "MULTIPOLYGON ("
+ + "((-102 37, -94 37, -94 40, -102 40, -102 37)),"
+ + "((-90 50, -80 50, -80 53, -90 53, -90 50)))";
+ Geometry input = geomFromWKT(wkt, 0);
+ Long[] cellIds = Functions.s2CellIDs(input, 10);
+ Geometry[] cells =
+
Functions.s2ToGeom(Arrays.stream(cellIds).mapToLong(Long::longValue).toArray());
+ Geometry coverage = Functions.union(cells);
+ assertTrue(
+ "S2 cell coverage does not contain every member of the MultiPolygon.",
+ coverage.covers(input));
+ }
+
+ @Test
+ public void testS2CoverageContainsMultiLineString() throws ParseException {
+ // Three disjoint multi-segment lines: northern hemisphere, southern
hemisphere, and a
+ // diagonal climb. Each is decomposed and buffered independently before S2
covering.
+ String wkt =
+ "MULTILINESTRING ("
+ + "(-102 37, -98 37, -94 37),"
+ + "(-90 -42, -85 -42, -80 -42),"
+ + "(-100 50, -95 55, -90 60))";
+ Geometry input = geomFromWKT(wkt, 0);
+ Long[] cellIds = Functions.s2CellIDs(input, 10);
+ Geometry[] cells =
+
Functions.s2ToGeom(Arrays.stream(cellIds).mapToLong(Long::longValue).toArray());
+ Geometry coverage = Functions.union(cells);
+ assertTrue(
+ "S2 cell coverage does not contain every member of the
MultiLineString.",
+ coverage.covers(input));
+ }
+
+ @Test
+ public void testS2CoverageContainsGeometryCollection() throws ParseException
{
+ String wkt =
+ "GEOMETRYCOLLECTION ("
+ + "POLYGON ((-102 37, -94 37, -94 40, -102 40, -102 37)),"
+ + "LINESTRING (10 60, 20 60, 30 60))";
+ Geometry input = geomFromWKT(wkt, 0);
+ Long[] cellIds = Functions.s2CellIDs(input, 10);
+ Geometry[] cells =
+
Functions.s2ToGeom(Arrays.stream(cellIds).mapToLong(Long::longValue).toArray());
+ Geometry coverage = Functions.union(cells);
+ assertTrue(
+ "S2 cell coverage does not contain every member of the
GeometryCollection.",
+ coverage.covers(input));
+ }
+
+ @Test
+ public void testS2CoverageContainsPolygonWithHole() throws ParseException {
+ // Outer ring at mid-latitude with long east-west edges; an inner hole.
Both rings need
+ // their great-circle bulge accounted for so the buffer applies to
interior rings too.
+ String wkt =
+ "POLYGON ("
+ + "(-102 37, -94 37, -94 40, -102 40, -102 37),"
+ + "(-100 38, -96 38, -96 39, -100 39, -100 38))";
+ Geometry input = geomFromWKT(wkt, 0);
+ Long[] cellIds = Functions.s2CellIDs(input, 12);
+ Geometry[] cells =
+
Functions.s2ToGeom(Arrays.stream(cellIds).mapToLong(Long::longValue).toArray());
+ Geometry coverage = Functions.union(cells);
+ assertTrue("S2 cell coverage does not contain a polygon with a hole.",
coverage.covers(input));
+ }
+
+ @Test
+ public void testS2CoverageContainsAntimeridianLine() throws ParseException {
+ // Edge crossing the antimeridian. The naive chord midpoint (a.x+b.x)/2
would land at
+ // 0° longitude — the opposite side of the planet — and produce a ~180°
bogus deviation.
+ // Verify that the buffer stays small (so we don't blow up the cell count)
and that the
+ // returned cells still cover the line.
+ Geometry line = geomFromWKT("LINESTRING (179 5, -179 5)", 0);
+ Long[] cellIds = Functions.s2CellIDs(line, 12);
+ Geometry[] cells =
+
Functions.s2ToGeom(Arrays.stream(cellIds).mapToLong(Long::longValue).toArray());
+ Geometry coverage = Functions.union(cells);
+ // Sanity check: a 2°-long edge near the equator at level 12 should not
produce
+ // millions of cells. If antimeridian chord-midpoint handling is wrong the
buffer
+ // explodes by ~180° and the cell count would be enormous.
+ assertTrue(
+ "Antimeridian-spanning line produced too many cells (chord midpoint
likely wrong): "
+ + cellIds.length,
+ cellIds.length < 5000);
+ assertTrue(
+ "S2 cell coverage of antimeridian-spanning LineString does not contain
the line.",
+ coverage.covers(line));
+ }
+
+ @Test
+ public void testS2CoverageContainsWideNonAntimeridianPolygon() throws
ParseException {
+ // Polygon spanning >180° in longitude but NOT crossing the antimeridian
(every edge has
+ // |Δlng| < 180°). An envelope-width-based antimeridian heuristic would
incorrectly skip
+ // the buffer here and reintroduce GH-2857 miscoverage along the long
east-west edges;
+ // the per-edge heuristic correctly leaves the buffer on.
+ String wkt = "POLYGON ((-100 30, 100 30, 100 50, -100 50, -100 30))";
Review Comment:
Good catch — fixed in 659a9eee12. The original WKT had four edges with
`|Δlng| = 200`, so my per-edge heuristic correctly flagged it as
antimeridian-crossing and the test was passing only because the buffer was
skipped (not for the reason the test name and comment claimed). New WKT `((-100
30, -10 30, 100 30, 100 50, 10 50, -100 50, -100 30))` keeps the envelope 200°
wide but every individual edge is under 180°, so the per-edge check returns
false and the buffer is actually applied — which is the path the test is meant
to exercise.
##########
common/src/main/java/org/apache/sedona/common/utils/S2Utils.java:
##########
@@ -107,13 +107,252 @@ public static Polygon toJTSPolygon(S2CellId cellId) {
return new GeometryFactory().createPolygon(coords);
}
+ /**
+ * Convert a JTS planar geometry into an S2Region whose lat/lng projection
is guaranteed to
+ * contain the input geometry.
+ *
+ * <p>Why a buffer is needed: Sedona geometries are planar — an edge between
two vertices is a
+ * straight line in (lng, lat) space — but S2 connects the same vertices
with a great-circle arc
+ * on the sphere. The two interpretations agree at the vertices but diverge
along the edges (e.g.
+ * the great-circle arc between two points at the same northern latitude
bulges northward, leaving
+ * the parallel that would form the planar chord). If we hand the JTS
vertices to S2 directly, the
+ * spherical polygon's interior is *smaller* than the planar polygon's
interior along
+ * non-meridional edges, so the S2 covering misses thin slivers of the
original planar polygon
+ * (see GH-2857).
+ *
+ * <p>To compensate, we JTS-buffer the input by an upper bound on the
worst-case great-circle
+ * deviation before converting to S2. A side effect for {@link LineString}
inputs is that the
+ * buffer turns the line into a polygon corridor; downstream callers
therefore see cells in a thin
+ * strip around the line rather than only cells the line geometrically
traverses.
+ */
public static S2Region toS2Region(Geometry geom) throws
IllegalArgumentException {
+ if (!(geom instanceof Polygon) && !(geom instanceof LineString)) {
+ throw new IllegalArgumentException(
+ "only Polygon or LineString (including LinearRing) types can be
converted to S2Region");
+ }
+ // JTS planar buffer doesn't understand antimeridian crossing — for inputs
that
+ // straddle the antimeridian, buffering produces a polygon that goes the
wrong way
+ // around the globe and explodes the S2 covering. Detect antimeridian
crossing
+ // per-edge (any edge with |Δlng| > 180° must wrap) rather than via the
envelope:
+ // the envelope-width heuristic also fires for wide non-straddling
polygons (e.g.
+ // a polygon spanning -100° to +100°), which would incorrectly skip the
buffer and
+ // reintroduce the GH-2857 miscoverage along their long non-meridional
edges.
Review Comment:
Fixed in 659a9eee12. You're right that a coarse `-100°→+100°` edge has
`|Δlng|=200` and gets classified as crossing under both heuristics, so it's not
the case where per-edge differs from envelope-width. Reworded the comment to
describe the actual differentiating case (a *tessellated* wide polygon with
intermediate vertices, where envelope width > 180° but every edge is < 180°),
and noted that for a coarse single-edge spanning > 180° both heuristics agree
and skipping the buffer is the safe choice anyway since JTS planar buffer can't
process such an edge usefully.
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