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Workflow Narrative
Parcel Fabric Topology Compliance
Who It Is For
- Local government cadastral teams and parcel QA workflows.
- Land administration vendors with regulatory topology compliance requirements.
Primary User
Municipal cadastral programs and land administration platforms.
What It Does
- Audits parcel fabrics for topology compliance using rule-based checks.
- Flags parcel slivers below a configurable minimum area threshold.
- Produces violations vector, issues CSV, and a compliance summary JSON.
- Optionally runs topology auto-fix and outputs corrected parcel geometry.
- Supports jurisdiction templates (`generic`, `ontario_mpac`) for calibrated defaults.
- Optionally emits a remediation queue CSV with prioritized corrective actions.
- Emits sliver-threshold calibration diagnostics so parcel fabrics can be profiled before tightening production thresholds.
How It Works
- Runs `topology_validation_report` to produce per-feature topology issue CSV.
- Runs `topology_rule_validate` with parcel-focused rules (`polygon_must_not_overlap`, `polygon_must_not_have_gaps`).
- Performs additional sliver detection on polygon area (`area < min_sliver_area`).
- Builds a `sliver_calibration_profile` over multiple threshold levels to show how many parcels would be flagged as slivers at each candidate cutoff when parcel area measurements are available.
- **Ontario MPAC sliver threshold calibration evidence (Mississauga, 166,758 parcels, EPSG:3857):**
- | Threshold | Parcel count below | % of total | Interpretation |
- |---|---|---|---|
- | < 0.25 m² | 54 | 0.032% | Digitising artifacts — flag unconditionally |
- | < 0.50 m² | 112 | 0.067% | Safe conservative threshold |
- | < 1.0 m² | 243 | 0.146% | Conservative production threshold |
- | < 2.0 m² | 508 | 0.305% | **Standard `ontario_mpac` default** — targeted alert rate |
- | < 5.0 m² | 1,870 | 1.12% | Liberal; may include very small utility parcels |
- | < 10 m² | 4,427 | 2.65% | Over-inclusive for most cadastral QA workflows |
- The 2.0 m² default for `ontario_mpac` is confirmed appropriate for dense urban parcel fabrics. Average parcel area in the Mississauga fixture is ~1,764 m²; maximum is ~4.1 km².
- Optionally runs `topology_rule_autofix` with fixable topology rules and emits corrected output.
- Optionally writes `remediation_queue_csv` with issue priority and recommended actions.
- Aggregates outputs into a compliance report with violation counts, sliver counts, sliver calibration profile, template metadata, and pass/fail gate.
Inputs
| Parameter | Type | Required | Description |
|---|
| `parcels` | PolygonVector path | Required | Input parcel polygon layer |
| `min_sliver_area` | float | Optional | Area threshold for sliver detection (default 1.0) |
| `auto_fix` | bool | Optional | Run topology auto-fix and emit corrected output (default false) |
| `jurisdiction_template` | string | Optional | Rule-template preset (`generic` | `ontario_mpac`) used for calibrated defaults |
| `topology_violations` | vector path | Required | Output topology violations layer |
| `issues_csv` | path | Required | Output topology validation CSV |
| `compliance_report` | path | Required | Output compliance summary JSON |
| `corrected_parcels` | vector path | Optional | Optional corrected parcel output path when auto_fix=true |
| `remediation_queue_csv` | path | Optional | Optional prioritized remediation action queue CSV |
| `html_report` | path | Optional | Optional output HTML path for the compliance dashboard report |
Outputs
| Output | Type | Contents |
|---|
| `topology_violations` | Vector | Rule violations generated by topology rule validation |
| `issues_csv` | CSV | Per-feature topology issue report from topology validation |
| `compliance_report` | JSON | Summary counts by rule, sliver diagnostics, sliver calibration profile, autofix summary, pass/fail |
| `corrected_parcels` | Vector | Auto-fix output when enabled and path provided |
| `remediation_queue_csv` | CSV | Priority-ranked remediation actions by issue type/rule |
| `html_report` | HTML | Optional compliance dashboard report with visual summary |
Python Example
env = WbEnvironment(license_tier="pro")
result = env.run_tool("parcel_and_land_fabric_topology_compliance_workflow",
parcels="parcel_fabric.gpkg",
min_sliver_area=1.0,
jurisdiction_template="ontario_mpac",
auto_fix=True,
topology_violations="output/parcel_violations.gpkg",
issues_csv="output/parcel_issues.csv",
compliance_report="output/parcel_compliance.json",
corrected_parcels="output/parcel_corrected.gpkg",
remediation_queue_csv="output/parcel_remediation_queue.csv",
html_report="output/parcel_compliance_report.html",
)
print(result)
License Notice
Use of this function requires a license for Whitebox Workflows Professional (WbW-Pro). Please visit www.whiteboxgeo.com to purchase a license.
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