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Reference index

Glossary

Requested geography
The geography a buyer asked for, in their own terms (a DMA, a radius, a named market).
Source geography
The geometry actually supplied — often not what was requested (a shapefile, a point list).
Normalized geometry
Source geometry repaired and reprojected to canonical EPSG:4326 GeoJSON.
Canonical H3
The interchange representation: a set of H3 cells at a stated resolution and containment rule.
Executed geography
What a platform actually ran — circles, polygons, or IDs approximating the H3 set.
Reported geography
The geography used in delivery/measurement reporting, frequently coarser than execution.
Attributed geography
The geography to which outcomes (conversions, lift) are credited.
Containment rule
The rule deciding which cells represent a polygon: center, full, intersect, or threshold.
Exactness
Approximation class of a conversion: exact, conservative, expansive, weighted, or approximate.
Inscribed circle
Largest disk centered at a cell center that fits inside the cell (⊆). No cross-cell overlap.
Circumscribed circle
Smallest disk containing the cell (⊇). Complete coverage; overlaps neighbours.
Compaction
Replacing a full set of children with their parent to shrink a mixed-resolution set losslessly.
Duplicate eligibility
Ground covered by more than one target — a frequency and measurement hazard.
Overreach
Executed area outside the requested source. underreach is the reverse.

Cell systems

Every system is named by its identity: a registered short token (the mono ids below) or an owner-controlled absolute https:// URI for an unregistered system — never a custom token. Its resolution span is machine-readable { min, max, name }. This is the convention from AdCP #6093 (identifier-based named places); the same identity is used for capability-map keys and the conversion tools’ by_geo wire block.

SystemIdResolutionsCellsEqual areaParent/childCompaction
H3h30–15 resolutionhexagon, pentagonapproximatelogicalyes
S2s20–30 levelquadrilateralnoexactyes
Geohashgeohash1–12 charactersrectanglenologicalno

Conversion methods

Execution formats

FormatProducesApproximationError introduced
Exact polygon / MultiPolygonpolygonexactNone beyond the cell discretisation itself, unless simplified to meet a vertex cap.
Inscribed circle (point + radius)point_radiusconservativeUnderreach — uncovered cell corners (~9% of a regular hexagon's area).
Circumscribed circle (point + radius)point_radiusexpansiveOverreach and overlap between neighbours → duplicate eligibility.
Equal-area circle (point + radius)point_radiusapproximateSimultaneous gaps and overlaps.
Optimized circle coverpoint_radiusapproximateBounded overreach; coverage defined on cell centres.
Administrative ID setplatform_geo_idapproximateBoundary vintage error; sub-unit precision loss; reported ≠ executed.
Platform-native geo IDsplatform_geo_idapproximateUnmatched/partial cells; namespace and vintage ambiguity.
Native H3 cell setcell_setexactNone, unless the platform coerces to a single resolution.

Edge-case catalogue (105)

External references

51 content pages · 18 methods · 105 edge cases · 4 platform models