Glossary

Test demo — not authoritative. Plain-English explanations of the automated data quality tests on this site. These are test results and proposals, not surveys, boundary determinations or legal advice. Thresholds below are read from the Duval config at publish time.

Issue types

Invalid geometry · Overlap · Contained parcel · Gap · Sliver polygon · Missing attribute (e.g. owner name) · Wrong attribute type · Required field absent · Duplicate parcel ID · Duplicate geometry · Missing geometry · Empty geometry · Out of bounds · Missing coordinate system · Unexpected coordinate system · ID field missing

Invalid geometry `geometry_invalid`

map colour #b388ff

What it means: The parcel's outline breaks the basic rules of a polygon — for example it crosses over itself (a 'bow-tie'), has a ring that touches itself, or repeats points.
Why it matters for parcels: Invalid shapes give wrong areas and break overlay, area and adjacency calculations, so every other test on that parcel is unreliable.
How GeoRescue detects it: Each shape is tested with the standard OGC validity rules (GEOS is_valid); the reason (e.g. 'Self-intersection') is shown in the message.
Automatic action: Automatically repaired in the output copy with make_valid — the only check that is auto-fixed by default. The source data is never changed.
Typical causes: Digitising errors, vertices snapped in the wrong order, format conversions.

Overlap `overlap`

map colour #ff9f1c

What it means: Two parcels claim the same piece of ground: their areas cross into each other.
Why it matters for parcels: Land normally belongs to one parcel. An overlap may point to a mapping error — or, rarely, to a real conflict between deeds that a professional should look at.
How GeoRescue detects it: Every pair of parcels whose interiors intersect by more than 10 sq ft (Florida East State Plane, US feet) (overlap_min_area) and that is not a near-total containment.
Automatic action: Proposal only. Not trimmed on the Duval run (trim_overlaps_below_area: 0); flagged as a candidate for deed checking.
Typical causes: Lines digitised from different sources, re-plats or splits not reconciled, old and new parcels both left in the map.

Contained parcel `contained_parcel`

map colour #ff4d6d

What it means: One parcel sits almost entirely inside another parcel — like a lot drawn on top of a larger tract instead of being cut out of it.
Why it matters for parcels: The larger parcel may be over-stating its acreage (the inner lot is counted twice), which can affect assessments and maps.
How GeoRescue detects it: An overlap that covers at least 98% of the smaller parcel (containment_min_fraction 0.98).
Automatic action: Proposal only: 'cut the smaller parcel out of the larger'. The smaller parcel is never deleted. Not applied unless cut_contained_from_container is turned on.
Typical causes: A parent tract not 'carved' after a split or new plat; stacked condo/common-area parcels.

Gap `gap`

map colour #4cc9f0

What it means: A small hole between parcels — ground that no parcel covers, enclosed by parcels all around.
Why it matters for parcels: Small holes are often slivers of mis-drawn boundaries rather than real unowned land.
How GeoRescue detects it: Interior holes in the union of all parcels up to 500 sq ft (Florida East State Plane, US feet) (gap_max_area). Larger holes (roads, water, unmapped land) are ignored.
Automatic action: Proposal only — reported, never filled automatically.
Typical causes: Neighbouring lines that don't quite meet; rounding; lines digitised from different sources.

Sliver polygon `sliver_polygon`

map colour #80ffdb

What it means: A parcel that is extremely small or extremely thin — a narrow strip rather than a normal lot.
Why it matters for parcels: Slivers are frequently leftovers of mismatched lines, though some are real (strips, easements, remnants).
How GeoRescue detects it: Area below 50 sq ft (Florida East State Plane, US feet) (sliver_max_area) or thinness score below 0.02 (sliver_max_compactness; 4π·area ÷ perimeter², where a circle is 1 and a long thin strip approaches 0).
Automatic action: Proposal only — reported for review.
Typical causes: Boundary mismatches between neighbours, remnant strips, right-of-way pieces.