Computer Vision

Use of Image Mosaicing for
Infrastructure Assessment
Juan Brugada
supervised by
Dr. Kenichi Soga, Prof. Roberto Cipolla
Engineering Department
Bond Street C125 Shaft Inspection
• Bolted Cast Iron rings 6m and 4m diameter with concrete
lining.
• Height: 20.5 m
• Photos taken at 28 levels within the shaft and at 9
locations within each level
• Photos stitched using Autostitch and Serif Panorama
software
Example
Stitched photos for each level
Level 1 H=0.6m
Level 2 H=1.2m
Level 3 H=1.8m
Level 4 H=2.6m
Level 5 H=3.2m
Level 6 H=3.6m
Level 7 H=4.1m
Level 8 H=4.6m
Level 9 H=5.1m
Level 10 H=5.6m
Level 11 H=6.1m
Level 12 H=6.6m
Level 13 H=7.1m
Level 14 H=7.6m
Level 15 H=8.1m
Level 16 H=8.9m
Level 17 H=9.5m
Level 18 H=10m
Level 19 H=11.3m
Level 20 H=12m
Level 21 H=13.6m
Level 22 H=15m
Level 23 H=16.4m
Level 24 H=17.8m
Level 25 H=18.5m
Level 26 H=19.2m
Level 27 H=20.2m
Level 28 H=20.5m
Stitching different Levels
Levels 21-24 (Stitched manually)
Levels 4 to 10 (Serif Panorama)
Levels 11 to 14 (Autostitch)
Levels 11 to 12 (Serif Panorama)
Levels 15 to 16 (Autostitch)
Levels 23 to 24 (Autostitch)
Levels 22 to 24 (Serif Panorama)
Combining Panoramas from
different Levels
Combined Panoramas Levels 4 to 10
Combined Panoramas Levels 11 to 12
Combined Panoramas Levels 5 to 6
Combined Panoramas Levels 20 to 21
Shepherd’s Bush DS-420B Shaft
Inspection
• Bolted cast iron rings 6m diameter, tiled with secondary
lining
• Height: 8.2 m
• Photos taken at 10 levels within the shaft and at 9
locations within each level
Level 1 H=0.32m
Level 2 H=1.9m
Level 3 H=2.3m
Level 4 H=3.2m
Level 5 H=4.6m
Level 6 H=5.1m
Level 7 H=5.7m
Level 8 H=6.3m
Level 9 H=6.9m
Level 10 H=7.5m
Stitching different Levels
Levels 1 to 5
Levels 5 to 8
Levels 9 to 10
The images can be used to create inspection charts
Image visualization
Images can be visualized using:
• UV mapping software as Unwrap3d in which images are
applied as texture to wireframe models
• Export to Quick Time or Real Player for cylindrical
panorama visualiztion
Images exported as Texture (Unwrap3d)
Images exported as Texture (Unwrap3d)
Images exported as Texture (Unwrap3d)
Images exported to Quick Time
Images exported to Quick Time
Example of QTVR visualization in infrastructure monitoring
Factors affecting the quality of the images
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Light intensity
Light direction
Focal Length of Lens
Object Distance
Aperture
Focus
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Digitizing rate
Field of View Balance
Exposure Time
Image Filtering
Working Distance
Lens Choice
Factors affecting mosaicing
• Change of aperture/exposure time
• Vignetting (Intensity decreasing towards the edge of the
image)
• Parallax effect due to unwanted motion of the optical
centre
• Radial distortion
Summary
• Photos of individual levels could be stitched due
to good overlap between images
• Difficulty stitching vertically due to lack of
overlap between photos at each level
• Combining panoramas from different levels is
possible with adequate overlap of photos
between levels
Summary
• Image-mosaicing can be used to supplement
inspection reports
• Useful for electronic incorporation of field data
• Further research into real-time mosaicing using
video software
Acknowledgements
The shaft inspection images shown in this
presentation were provided by Mr. Christopher
Chew and Mr. Kevin Roberts of Metronet