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.

Project Links

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