GeoStandardPath outside distance measures end caps (and one-point paths) to the end point instead of the cap edge, so values are too large by up to the path half-width and Geo3DDocValuesField.newOutsidePathSort misorders documents
Finding LFV-735Area: spatial3d / geom path outside distance (GeoStandardPath segment endpoints; Geo3DDocValuesField.newOutsidePathSort)Priority: lowImpact: silent wrong resultsNovelty: new
AI-assisted finding, confirmed by automated checks, not yet triaged by a human Lucene committer. This site files nothing upstream.
What it shows
You build a path with a width (GeoPathFactory.makeGeoPath, or the pathWidthMeters of Geo3DDocValuesField.newOutsidePathSort) and ask for the outside distance of a point beyond one of its ends, expecting 'the distance from a point to the closest outside edge' (GeoOutsideDistance), which is how the same path measures points beside its segments and how GeoCircle measures a circle. Instead you get the distance to the path's end point, i.e. the gap plus up to the half-width: on the unit sphere a point 0.001 rad beyond the end of a path of half-width 0.01 gets 0.011, a one-point path reports 0.011 where the same-size GeoCircle reports 0.001, the value jumps from 0 to about the half-width as a point crosses the end cap's edge, and on WGS84 the outside-path sort ranks a document 1 km beyond the end of a path of half-width 5 km (5992 m) after one 3 km beside it (3067 m). The cause is BaseSegmentEndpoint.outsideDistance, which every endpoint with a width inherits: it measures to the end point itself, which is the edge only for a zero-width path.
The test shows that a GeoStandardPath measures the outside distance beyond an end cap to the end point, not to the cap edge: SPHERE path (0,0)-(0,0.1) of half-width 0.01, point (0, 0.111).
Expected vs actual
Expected (GeoOutsideDistance: distance to the closest outside edge, which is at longitude 0.11): 0.001. Actual: 0.010999999999988425 (expected:<0.001> but was:<0.010999999999988425>).
Files
Run it
- Tested on Lucene main e1faeba08bde (2026-11-02): still reproduces.
- Tested on Lucene main 645d4fe14a20 (2026-10-28): reproduced.
- Recorded outcome of run 1 on Lucene main 645d4fe14a20: 1 test(s) run, 1 failed.
- How to read the outcome: a failing test is the finding reproducing (the failure message states expected against actual).
- Seeds: a rerun with the same seed replays the same random choices. Assertions off (-da -dsa -Dtests.asserts=false) is the production-like setting.
# Lucene checkout at the tested commit, built with: ./gradlew --no-daemon assemble (JDK 25)
LUCENE=/path/to/lucene; V=12.0.0-SNAPSHOT
CP=$LUCENE/lucene/core/build/libs/lucene-core-$V.jar
CP=$CP:$LUCENE/lucene/codecs/build/libs/lucene-codecs-$V.jar
CP=$CP:$LUCENE/lucene/test-framework/build/libs/lucene-test-framework-$V.jar
CP=$CP:$LUCENE/lucene/spatial3d/build/libs/lucene-spatial3d-$V.jar
CP=$CP:randomizedtesting-runner-2.9.2.jar:junit-4.13.2.jar:hamcrest-3.0.jar # test-framework dependencies (Maven Central)
CP=$CP:junit-platform-console-standalone-6.1.3.jar # JUnit Platform console launcher (Maven Central)
javac -d classes -cp "$CP" $(find src -name '*.java')
# run 1: assertions on, seed DEADBEEF
java -ea -esa --add-modules jdk.incubator.vector --enable-native-access=ALL-UNNAMED -Dtests.seed=DEADBEEF \
-cp "classes:$CP" org.junit.platform.console.ConsoleLauncher \
execute --select-class org.apache.lucene.spatial3d.geom.TestGeoPathOutsideDistanceEndCapGradle alternative: copy the test into the matching module's src/test/ tree of the checkout and run ./gradlew -p lucene/<module> test --tests <class> -Ptests.seed=<seed> (add -Ptests.asserts=false for a run without assertions).
Feedback
Open an issue in lucene-ai-bug-hunt. Please do not open issues or pull requests in apache/lucene about this finding unless a Lucene committer agrees it should be filed.
Snapshot of 2026-11-04. AI-assisted; not yet triaged by a human Lucene committer. Feedback: open an issue in lucene-ai-bug-hunt.