GeoExactCircle.computeOutsideDistance never measures the slice end points where two of its approximation slices meet, so a point outside whose nearest edge point is such a joint gets +Infinity or the distance to the far side of the circle: on WGS84 every point due north or due south of the centre, at any radius; on the sphere a point 0.001 rad due west of a 1e-4 rad exact circle gets 0.0012

Finding LFV-737Area: spatial3d / geom exact-circle outside distance (GeoExactCircle.outsideDistance, reached through GeoCircleFactory.makeExactGeoCircle and GeoOutsideDistance.computeOutsideDistance)Priority: lowImpact: silent wrong resultsNovelty: new

Finding page for LFV-737

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 an exact circle on the default WGS84 planet model (GeoCircleFactory.makeExactGeoCircle, centre latitude 0.3 and longitude 0.2, radius 0.1 rad, about 637 km, accuracy 1e-6) and ask computeOutsideDistance for a point 0.11 rad due north of the centre, expecting 'the distance from a point to the closest outside edge' (GeoOutsideDistance), about 0.0096. Instead you get +Infinity, and the same for every point due north or due south at any distance; on the unit sphere a point 0.001 rad due west of a 1e-4 rad exact circle gets 0.0012, the distance to the far side of the circle. The cause: GeoExactCircle.outsideDistance takes the minimum of each slice's plane distance bounded to that slice's sector and never measures the slice end points, so when the nearest edge point is a joint between two slices, the point's foot on each neighbouring plane falls just outside its sector, both return +Infinity, and the minimum is +Infinity or a foot on the far side.

The test shows that GeoExactCircle.computeOutsideDistance returns +Infinity for a point due north of a WGS84 exact circle, because it never measures the slice end point (the joint where two slices meet) that is the closest edge point.

Expected vs actual

Expected: about 0.009558, the ARC distance from (0.41, 0.2) to the circle's north edge point. Actual (-ea and -da): +Infinity.

Files

• src/org/apache/lucene/spatial3d/geom/TestGeoExactCircleOutsideDistance.java (JUnit test)

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.TestGeoExactCircleOutsideDistance

Gradle 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 2026-11-03. AI-assisted; not yet triaged by a human Lucene committer. Feedback: open an issue in lucene-ai-bug-hunt.