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[GH-2396] Making splitting polygon by line robust by removing the computation of line-polygon intersection #2598

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Merged
jiayuasu merged 2 commits into from
Jan 22, 2026
Merged

[GH-2396] Making splitting polygon by line robust by removing the computation of line-polygon intersection #2598

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c93152a
Fix polygon split by line by replicating the logic from PostGIS
Kontinuation Jan 22, 2026
9d1c866
Remove unnecessary function
Kontinuation Jan 22, 2026
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19 changes: 13 additions & 6 deletions common/src/main/java/org/apache/sedona/common/utils/GeometrySplitter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -262,13 +262,9 @@ private void splitOnCoord(LinearGeometryBuilder lineBuilder, Coordinate coord) {
}

private Geometry generateCandidatePolygons(Geometry polygons, Geometry blade) {
// restrict the blade to only be within the original polygon to
// avoid candidate polygons that are impossible
Geometry bladeWithinPolygons = blade.intersection(polygons);

// a union will node all the lines at intersections
// these nodes are required for Polygonizer to work correctly
Geometry totalLineWork = polygons.getBoundary().union(bladeWithinPolygons);
Geometry totalLineWork = polygons.getBoundary().union(blade);

Polygonizer polygonizer = new Polygonizer();
polygonizer.add(totalLineWork);
Expand All @@ -281,7 +277,18 @@ private void addValidPolygonsToList(Geometry polygons, Geometry original, List<P
// original geometry to ensure holes in the original geometry are excluded
for (int i = 0; i < polygons.getNumGeometries(); i++) {
Geometry candidateResult = polygons.getGeometryN(i);
if (candidateResult instanceof Polygon && original.contains(candidateResult)) {
if (!(candidateResult instanceof Polygon)) {
continue;
}

Point pointOnSurface = candidateResult.getInteriorPoint();
// getInteriorPoint() may return null for degenerate or empty polygonal geometries,
// so guard against null before using the point.
if (pointOnSurface == null) {
continue;
}

if (original.covers(pointOnSurface)) {
list.add((Polygon) candidateResult);
}
}
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30 changes: 30 additions & 0 deletions common/src/test/java/org/apache/sedona/common/FunctionsTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -531,6 +531,36 @@ public void splitHeterogeneousGeometryCollection() {
assertNull(actualResult);
}

@Test
public void splitCircleInto2SemiCircles() throws ParseException {
String polygonWkt =
"POLYGON ((-117.76405581088967 34.111876749328026, -117.76407506132291 34.11170068822483, "
+ "-117.76413523652074 34.111531133837936, -117.76423402376724 34.11137460199335, -117.76436762657538 34.11123710803779, "
+ "-117.76453091060647 34.11112393568514, -117.76471760098879 34.11103943398174, -117.76492052345083 34.11098685019075, "
+ "-117.76513188000408 34.1109682050154, -117.76534354858369 34.11098421495394, -117.76554739513688 34.11103426476887, "
+ "-117.76573558617179 34.11111643112786, -117.76590088976099 34.111227556508084, -117.76603695343799 34.11136337052523, "
+ "-117.76613854831002 34.11151865402651, -117.76620177000793 34.11168743964393, -117.76622418874936 34.111863241103265, "
+ "-117.76620494274577 34.11203930247842, -117.76614477135817 34.11220885781403, -117.7660459867224 34.11236539113964, "
+ "-117.76591238492807 34.11250288688306, -117.7657491001595 34.11261606105824, -117.7655624074007 34.11270056434135, "
+ "-117.76535948128496 34.112753149228745, -117.76514812035703 34.11277179485027, -117.76493644734776 34.112755784639766, "
+ "-117.76473259698435 34.112705733876126, -117.76454440333869 34.11262356603611, -117.76437909873567 34.11251243886801, "
+ "-117.76424303579616 34.11237662302835, -117.76414144330062 34.112221337947354, -117.76407822525644 34.11205255123353, "
+ "-117.76405581088967 34.111876749328026))";
String knifeWkt =
"LINESTRING (-117.7640751398563 34.111535124121441, -117.76628486838135 34.112204866513046)";

Geometry polygon = Constructors.geomFromWKT(polygonWkt, 4326);
Geometry knife = Constructors.geomFromWKT(knifeWkt, 4326);
Geometry resultPolygon = Functions.split(polygon, knife);
assertEquals(2, resultPolygon.getNumGeometries());

double circleArea = polygon.getArea();
for (int i = 0; i < resultPolygon.getNumGeometries(); i++) {
double actualArea = resultPolygon.getGeometryN(i).getArea();
assertEquals(2.0, circleArea / actualArea, 0.1);
}
}

@Test
public void dimensionGeometry2D() {
Point point = GEOMETRY_FACTORY.createPoint(new Coordinate(1, 2));
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