Dataset Compare
Compare two vector datasets by a unique key field — classify added, removed, attribute-changed, and geometry-changed features.
How to use
- Pick a "before" and an "after" dataset from your workspace, or paste a fresh GeoJSON for either side.
- Choose a field that uniquely identifies each feature (a parcel id, a station code, ...) — this must be unique on both sides, or that key is excluded and reported as ambiguous rather than guessed at.
- Set a numeric tolerance and/or a coordinate tolerance (in degrees) if you want small, expected differences to count as unchanged, then click a summary count to show/hide that change type on the map and table.
- This compares two vector snapshots' attributes and geometry — it's not satellite-imagery change detection.
- The coordinate tolerance is in degrees (WGS84), never meters — applying a meter-scale tolerance directly to lon/lat values would be off by roughly 5 orders of magnitude.
Compares two vector datasets by a key field you choose — this is a vector attribute/geometry diff, not satellite-imagery change detection. A key that isn't unique in either dataset is excluded from the comparison and reported separately, never matched by row position.
Pick or paste both a "before" and an "after" dataset, and a key field, to run the comparison.
Dataset Compare Coverage
Compares two vector datasets by a key field you choose, classifying each key as added, removed, attributes-changed, geometry-changed, both-changed, or unchanged. A key that isn't unique in either dataset is excluded from the comparison and reported separately, never matched by row position.
Numeric tolerance and coordinate tolerance (in degrees, WGS84) are both explicit, so a small expected difference doesn't get flagged as a real change. This compares two vector snapshots' attributes and geometry — it is not satellite-imagery change detection.
Frequently asked questions
Can I compare data without a unique identifier?
You must still choose a key field — if its value repeats on either side, that key is excluded from the comparison and reported as ambiguous rather than guessed at via row order.
Is the coordinate tolerance in meters?
No — always in degrees (WGS84). Applying a meter-scale tolerance directly to lon/lat values would be off by roughly 5 orders of magnitude, so this tool keeps the unit fixed to degrees.