Vector Handover Review

Professional Mistakes — Vector GIS

Use this checkpoint before accepting responsibility for a vector derivative.

Mistake	Why it happens	Detect	Prevent	Potential consequence
Treating the DataFrame index as scientific ID	row labels look unique	reorder or export and compare	create, validate and preserve a stable ID	records cannot be traced across stages
Trusting visual overlap	the map looks convincing	compare CRS, bounds and control evidence	audit metadata and known positions	systematically displaced results appear valid
Buffering geographic coordinates	the layer already draws correctly	inspect CRS units before distance work	transform to a justified projected CRS	meaningless or latitude-dependent distances
Using intersects for every relationship	it returns many plausible matches	test boundary and containment cases	define the scientific relationship first	boundary contacts become false assignments
Deleting unmatched features	complete tables look cleaner	reconcile left-side IDs before and after	retain and classify unmatched records	missingness and sampling bias are hidden
Dropping one-to-many rows as duplicates	repeated IDs resemble errors	inspect matched right-side IDs and geometry	declare cardinality and aggregation policy	legitimate relationships are erased
Nearest assignment without a threshold	every feature receives an answer	map distance distribution and far matches	use projected units and a justified maximum distance	unrelated features are attached
Assuming valid geometry means valid topology	each feature passes is_valid	inspect overlaps, gaps and coverage rules	test dataset-level expectations	contradictory or incomplete coverage persists
Auto-repairing without review	software returns a valid result	compare type, count, area and boundaries	preserve source and review repair candidates	real features are split, collapsed or moved
Ignoring spatial-index performance	small examples run quickly	calculate n × m and profile controlled cases	use indexed operations and verify equivalent IDs	scaling prompts manual shortcuts or incomplete QA
Overwriting raw layers	a fix feels final	check whether an immutable input remains	write named derivatives only	provenance and recovery are lost
Failing to reopen derivatives	successful write feels complete	read the delivered file in a fresh step	validate CRS, schema, counts and geometry after write	corrupt or incomplete handovers escape review

Chapter 2 Practicum — Vector Handover Review

Professional outcome

By the end of this practicum, you will be able to accept, conditionally accept or reject a vector delivery using reproducible Python evidence and independent QGIS inspection.

1. Client request

An environmental consultancy receives synthetic field points, management polygons and habitat polygons. The client asks for “one clean analysis-ready GeoPackage.” That phrase is not a specification. Your first responsibility is to define what analysis-ready means for the proposed spatial assignments while preserving unresolved evidence.

Use the clean training pack for intended relationships and the separately labelled corrupted topology derivative for diagnostic practice. Never replace the clean source with the corrupted or repaired copy.

Check your understandingEvery feature is individually valid. What still requires review?

Choose one answer

Dataset-level overlaps, gaps, duplicates and coverage rulesNothing; feature validity proves the handoverOnly map colours

Check answer

2. Complete the fifteen-step review

1. Audit every file, layer, feature count, geometry type and extent
2. Verify source CRS evidence, axes, units and analysis CRS
3. Check stable IDs for nulls, uniqueness and preservation
4. Diagnose missing, empty, invalid, multipart and duplicate geometry separately
5. Test dataset topology for overlaps, gaps, slivers, unintended holes and coverage expectations
6. Resolve only documented defects; preserve rejected and unresolved candidates
7. Define each attribute or spatial relationship and predicate before execution
8. Perform joins with traceable left and right IDs
9. Audit input/output counts, unmatched cases, one-to-many results and unused right-side features
10. Profile a repeated predicate or join and verify indexed/naive equivalence
11. Reconcile Python evidence in QGIS, including TP04, TP05, assignments and topology defects
12. Write named layers to vector_handover_review.gpkg without overwriting sources
13. Reopen the GeoPackage and rerun schema, CRS, count, ID and geometry checks
14. Create a QA map that exposes decisions and unresolved cases
15. Write a short handover note with fitness, limitations, owners and next actions

3. Required integrity report

Create vector_integrity_report.csv with at least:

check_id, layer, feature_id, condition, expected, observed, severity, decision, evidence, owner, status

Keep two outputs distinct:

• the integrity report, which retains every finding and decision
• the repaired derivative, which contains only explicitly accepted geometry changes

A clean-looking derivative without its integrity report is not a complete handover.

Check your understandingPython and QGIS show different assignment counts. What comes first?

Choose one answer

Reconcile inputs, CRS, predicate, filters and versionsKeep whichever output has fewer nullsManually edit the QGIS table

Check answer

4. Reconciliation rules

Python and QGIS should reproduce the same declared relationships. Visual agreement is useful evidence, but it is not numerical proof. Reconcile:

• source path, CRS and feature count
• TP04 boundary behaviour and TP05 outside status
• management and vegetation-zone assignments
• invalid, overlap, gap, duplicate and sliver cases
• changed geometry IDs and post-repair status

If results differ, compare input versions, selected-feature filters, predicate direction, tolerance, precision and software version. Do not choose the answer with fewer unresolved records.

5. QA map and handover decision

The map must include a precise purpose, CRS, scale where relevant, synthetic-data label, source/provenance note, stable IDs for review cases and a legend that distinguishes accepted, unresolved and rejected conditions without relying on colour alone.

End HANDOVER_NOTES.md with one status:

• accepted for the defined analysis
• conditionally accepted with listed restrictions
• rejected pending listed evidence or correction

Check your understandingWhat makes a vector derivative ready for handover?

Choose one answer

Traceable inputs, passed QA, declared limitations and reproducible outputsA visually attractive mapA successful file write

Check answer

Scientific interpretation

This review can establish that the delivered vector relationships and derivatives satisfy declared structural and computational rules. It cannot establish ecological boundary truth, survey accuracy or temporal relevance beyond the supplied evidence.

Submission

• vector_handover_review.ipynb
• vector_handover_review.gpkg
• vector_qa_map.pdf or vector_qa_map.svg
• vector_integrity_report.csv
• HANDOVER_NOTES.md

Portfolio artifact

Artifact 2.B — Analysis-ready vector handover

Add the notebook, GeoPackage, integrity report, QA map and handover note as one reviewable package in the UAV and Satellite Analysis Pipeline.