Check and Update

The Check and Update tool provides a complete, unified workflow for administrative boundary management: Georeferencing & Digitizing Navigation, PSGC Geocode Left-Join Metadata Enrichment, and Chronological Geometry Error Scanning & Repair.

Access

• Menu: Gemma → Updating of Boundaries → Check and Update
• Component Algorithm IDs: gmd_pipeline:scangeometryerrors, gmd_pipeline:repairpolygongeometries, gmd_pipeline:join_barangay_attributes, gmd_pipeline:update_lgu_with_psgc, gmd_pipeline:update_lgu_by_geocode

Workflow Sections

Pre-Processing Workflow

The Pre-Processing tab contains a 3-step sequential interface (Georeferencing ➔ Digitize ➔ Update and Export):

1. Georeferencing

• Open QGIS Georeferencer: Launches QGIS's built-in Georeferencer window directly from the plugin dialog to align raster basemaps, scanned map sheets, or aerial imagery to ground control points (GCPs) with default working directory set to C:\PSA-GIS.

2. Digitize & Navigation

• PSA Reference Layer & Opacity: Selects the active PSA reference polygon layer (automatically suggesting layers ending in *_psa). Adjust layer transparency (0% to 100%, defaulting to 25%) with the Apply button to overlay boundary features clearly over raster basemaps.
• Adjust Feature Selection: Dropdown automatically lists all barangay features from the active reference layer using its barangay attribute column.
• Feature Editing Controls:
  • Edit: Activates digitizing mode for the highlighted feature. Automatically:
    • Zooms the map canvas directly to the feature's bounding box.
    • Opens the QGIS Vertex Tool for node editing.
    • Activates the Feature Edit Guard, locking vertex edits strictly to the active feature ID and automatically reverting accidental vertex edits on neighboring polygons.
    • Configures Advanced Snapping (12.0px tolerance, Vertex & Segment, Topological Editing, Self-Snapping enabled, Intersection Snapping disabled, Avoid Overlap).
    • Ensures the QGIS Topology Checker plugin is enabled and loaded into memory, displaying the panel when editing starts.
    • Minimizes the main dialog window and displays the dockable Gemma Digitize Navigation Panel (DigitizeDockWidget) in the lower-left workspace (providing Previous, Next, Save (Done), Return, and feature selector dropdown).
  • Previous / Next: Cycles through features in alphabetical/sequential order, re-zooms map canvas automatically, and triggers Validate All on the Topology Checker dock panel.
  • Save (Done): Concludes the digitizing session, prompting the user to Save, Discard, or Cancel pending revisions.

3. Update and Export

• Embedded Parameter Controls:
  • Layer Selection: Reuses the PSA Reference Layer selected in Step 2 (Digitize), eliminating duplicate layer selection fields.
  • LGU Geocode Field: Dropdown auto-detects and suggests candidate geocode fields (e.g. geocode, psgc, code, lgu_code).
  • LGU Barangay Name Field: Dropdown auto-detects and suggests candidate barangay name fields (e.g. barangay, lgu_bgy_name, brgy_name).
  • Hidden Defaults: Uses standard default values behind the scenes (Source = 'LGU', Source Year = '2026', Open Output = True).
  • Smart Folder Resolution: Automatically saves the GeoPackage output into the physical directory folder of the input layer on disk. If the layer is a temporary memory layer, it falls back to the QGIS Project directory or user's Documents folder.
• Action Button (Update & Export (as GPKG)):
  • Immediate Visual UX Feedback: Disables the button on click, updates text to "Updating & Exporting... Please wait...", applies a busy visual style, sets mouse cursor to Qt.WaitCursor (spinner/hourglass), and forces an immediate UI repaint via processEvents().
  • 8-Digit Concatenated Key Matching: Matches the first 8 characters of the LGU layer geocode against the concatenated PSGC reference key (province_code + city_mun_code + barangay_code, e.g. 801 + 00 + 001 $\to$ 80100001), supporting 8, 9, and 10-digit geocodes seamlessly.
  • Browser-Style Auto-Numbering: If the output file (e.g. 00509_bgy.gpkg) already exists or is locked in QGIS, it automatically creates 00509_bgy (1).gpkg, 00509_bgy (2).gpkg, etc. without crashing or throwing OGR file locked errors.
  • Database NULL Handling: Populates unmatched or empty fields (remarks, hhcount, bldgcount, bdry_status) with database NULL (QVariant()) values instead of empty strings.
  • 16-Field Output Schema: Outputs standard attribute schemas: fid (Integer), map_uuid (String, 36), geocode (String, 50, preserved from input LGU layer), region (String, 100), province (String, 100), city_mun (String, 100), barangay (String, 100), code (String, 50, defaulted to '1003'), remarks (String, 255, NULL), source (String, 100, 'LGU'), hhcount (Integer, NULL), bldgcount (Integer, NULL), sy (String, 10, '2026'), boundary (String, 20, 'Barangay'), lgu_bgy_name (String, 100), and bdry_status (String, 20, NULL).

Geometry Check & Repair Workflow

The Geometry Check & Repair tab provides a 3-step chronological workflow for scanning, inspecting, and repairing defective polygon geometries:

1. Target Layer & Check Error Options: Choose the target polygon vector layer and select error types to evaluate (Null, Empty, Invalid GEOS, Self-Intersections, Wrong Geometry Type, Duplicate Geometries).
2. Step 1: Scan Geometry Errors:
   • Executes gmd_pipeline:scangeometryerrors.
   • Populates an interactive Detected Errors Table (FID, Layer, Error Type, Description, Auto-fixable).
   • Loads a Point Error Layer (Geometry_Errors_<layer_name>) into QGIS for spatial visualization.
3. Interactive Table Selection & Canvas Zoom:
   • Double-click any table row to zoom the QGIS map canvas directly to that defect.
   • Multi-select specific table rows to target specific error features for repair.
4. Step 2: Repair Polygon Geometries:
   • Executes gmd_pipeline:repairpolygongeometries.
   • If specific table rows are highlighted, repairs only those selected features.
   • If no rows are selected, repairs all detected errors across the layer.
5. Step 3: UPSERT Repaired Features to Layer:
   • Merges clean repaired geometries into a complete updated version of the target polygon layer (Updated_<layer_name>).
   • Replaces defective features while preserving all untouched valid features.