Building Inspection and Large Area Surveying Using UAVs

Jonathan Byrne

Urban Modelling Group (UMG)

University College Dublin

Ireland

Urban Modelling Group



link

Structural Analysis

Wind Tunnel Modelling

UAV Scanning:

  • Low cost
  • Easily capture multiple angles
  • Real-time feedback
  • Centimetre accurate models
  • Spatial image database
  • Limited range
  • Limited battery life
  • Legal restrictions

Traditional Photogrammetry

Low Altitude Parallax

Structure from Motion

  1. Find features (edges, corners)
  2. Match images
  3. Align images
  4. Generate point cloud
  5. Generate and texture mesh

Feature Detection

Alignment



link

Generate Point Cloud



link

Mesh and Texture



link

Applications:

  • Building, roof and bridge inspection
  • Ortho-rectified maps
  • Digital elevation models
  • Volume measurement
  • Point cloud generation
  • Fully textured and geo-referenced models
  • BIM integration
  • Measurement models and linework
  • Digital historical archives

Boland's Mills:


link

Area: 0.01 km², 2.52 acres, 1 hectare

Accuracy

Spatial Image Database

Boyne Viaduct:


link

Area: 0.02 km², 3.74 acres, 1 hectare

Ground Survey

Aerial Survey 1

Aerial Survey 2

Model interaction

Large Aerial Surveys

  • 10-500 Hectares
  • Normally conducted by fixed wing aircraft
  • Height trades off accuracy for speed
  • Incorporate ground control points from traditional surveying

Greystones to Kilcoole



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Area: 3.6 km², 88 acres, 36 hectares

Ground Control Points

Vertical vs Oblique (Angled)

Vertical

2.2 Hectares

30 Degree Oblique

4.6 Hectares

40 Degree Oblique

10 Hectares

Vertical

2.2 Hectares

30 Degree Oblique

4.6 Hectares

60 Degree Oblique

10 Hectares

UCD: Urban Large Area Survey



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Area: 1.1 km², 271.82 acres, 110 hectares

Connolly's Folly and Kilmacredock Survey

Area: 3.03 km², 749.79 acres, 303.43 hectares

3D Model



link

Area: 3.03 km², 749.79 acres, 303.43 hectares

Accuracy:

  • Model accuracy at 100 meters: 5 centimeters (GSD)
  • Model accuracy at 50 meters: 2 centimeters (GSD)
  • Georeference accuracy with GPS: approx 1-5 meter
  • Georeference accuracy with RTK: approx 2-4 cm

Future Work:

  • Improvements in Structure From Motion algorithm
  • Simultaneous Localisation and Mapping
  • Flight path planning
  • Coordinated UAV scanning
  • Visualisation over the internet link

Other surveys:

  • Bandon, Co. Cork
  • Trim Castle
  • Newtown Abbey, Trim
  • Slane, co Meath

Thanks

umg.ucd.ie

3dsurveyingservices.ie