Topology Tools

Boundary cleaning

1. 1

   Step 1: Schema

   Map source columns to admin code and name columns, then apply the crosswalk.

   

   Schema Map

   Infer a polygon layer's admin hierarchy crosswalk, review and edit it in place, and apply it to download the renamed layer, the crosswalk CSV, or both.

   Show 2 individual tools

   

   Schema Join

   Copy a join layer's admin hierarchy columns onto each input feature by largest overlap, keeping conflicting values as numbered siblings.

   

   Schema Fill

   Cascade each admin-hierarchy column family down from its deepest non-empty level, and stamp every row with its real depth.

2. 2

   Step 2: Topology

   Find gaps and overlaps between units, then clean them.

   

   Topology Cleaner

   Detect overlaps and gaps in a polygon coverage and clean them automatically, with an adjustable gap-width threshold.

   Show 1 individual tool

   

   Detect

   Scan a polygon layer for gaps and overlaps and report them without fixing anything (read-only).

3. 3

   Step 3: Edge matching

   Fit units to a reference boundary so the outer edge follows the agreed outline.

   

   Edge Matcher

   Match fine polygons to their best-overlapping coarse boundary (admin 4 into 3, admin 4 into 0, or any other pair), then extend each group to fit its boundary exactly.

   Show 2 individual tools

   

   Edge Extender

   Fill gaps between adjacent polygons by extending boundaries outward with Voronoi diagrams.

   

   Mosaic

   Fit an already-extended input layer into a new overlay boundary. Assign, clip, and close seams in one pass, no re-extension.

   

   Clip

   Assign an input layer to its one best-overlapping overlay feature by majority vote, then clip every input feature to that boundary.

   

   Stitch

   Close seams in an already-tiled polygon layer with a single whole-table coverage-clean pass.

4. 4

   Step 4: Codes

   Keep the previous release's codes for units that carry over, or cold-start codes when there is no previous release.

   

   Code Update

   Reconcile an already-coded layer against an uncoded candidate: retain codes for unchanged units, assign fresh ones for the rest.

   Show 2 individual tools

   

   Code Refactor

   Cold-start a hierarchical admin code on a flat polygon layer, ranked per parent and zero-padded to a configurable width.

   

   Changelog

   Compare two versions of a polygon layer and classify each unit as unchanged, modified, merged, split, created, or removed.

5. 5

   Step 5: Names

   

   Review names by hand: duplicates under the same parent, near-duplicate typos, blanks and placeholders, and encoding artifacts.

6. 6

   Step 6: Packaging

   Build per-level polygons, label points, and the boundary line network for release.

   

   Package

   Run Package Polygons, Package Points, and Package Lines against the same layer in one pass.

   Show 3 individual tools

   

   Package Polygons

   Dissolve a polygon layer up to every coarser admin level it contains, one output file per level.

   

   Package Points

   Produce one representative point per admin unit, at every level a polygon layer's hierarchy contains.

   

   Package Lines

   Extract every shared and exterior boundary edge in a polygon layer, classified by the coarsest level at which two neighbours diverge.