Use of Image Mosaicing forInfrastructure Assessment

Juan Brugadasupervised by

Dr. Kenichi Soga, Prof. Roberto CipollaEngineering 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 9locations 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 9locations 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

• Light intensity• Light direction• Focal Length of Lens• Object Distance• Aperture• Focus

• 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