3 rd Annual Optech ILRIS-3D Users Meeting Rome, Italy - June 6-7, 2007

1. 3rd Annual Optech ILRIS-3D Users MeetingRome, Italy - June 6-7, 2007 Efficient Road Mapping Modeling of Highways, Roads and Pavements using Laser Scanner Technology Michael Xinogalos Surveying Engineer NTUA ASTROLABE ENGINEERING / JGC

2. Applications • Highway survey and modeling (“as –built” record, background for design and construction) • Airport tarmac modeling and evaluation (maintenance) • Road intersection survey, design of interventions to improve safety, 3D modeling and integration, video simulations (evaluation of proposed measures)

3. Location: Central Peloponnesos, Greece • Self Financing Project: Construction of a new highway section / Reconstruction and Maintenance of an existing highway section – J/V MOREAS • Existing Highway: Dual Carriageway, 2-3 lanes & shoulder “Korinthos – Tripoli” Highway

4. Existing highway survey requirements • Detail “as built” survey of all highway features (pavement, structures, slopes, signage, poles, etc.) • Efficient archiving of “as built” situation for future reference • Positional accuracy of georeferenced points: 2-3 cm • 3D model (TIN) for highway reconstruction design • Background survey maps (scale 1:500) • No traffic closure or delay • Efficient safety plan • Permits from local traffic authorities “Korinthos – Tripoli” Highway

5. Project tasks (1/4) • Establishment of geodetic infrastructure networks (triangulation, leveling, polygonometry), also necessary for construction • Static (stop & scan) laser scanning with Optech ILRIS36D • Scanner carried by a vehicle moving or standing always on the shoulder lane, protected by a traffic regulation trailing vehicle • Scanning from both sides of the highway, distance between scanning positions 50-80m “Korinthos – Tripoli” Highway

6. Project tasks (2/4) • Critical issue for horizontal objects: lifting the scanner (better scanning angle, improved object visibility, lower scanning resolution and / or fewer scanning positions required) • Lifting device used: Genie Super Hoist (5.6m, 113 kg capacity, CO2) • Custom modifications: Trailer integration, 5/8 bolt, longer ethernet and power cables, stabilizers, fuel generator & UPS, etc. “Korinthos – Tripoli” Highway

7. Project tasks (3/4) • Scanning resolution: 55mm @ 25m horizontal / 20mm @ 25m vertical • Pan-tilt base overlap set to maximum (20% overlap, 15 frames/3600) • Primary georeferencing: with conic targets (standard traffic cones: easy to install, measure and model), 1 cone (anchor point) per scan position required for sequential georeferencing (Polyworks IMAlign - IMInspect) “Korinthos – Tripoli” Highway

8. Project tasks (4/4) • Georeferencing refinement for elevations: using additional points measured with GPS on the shoulder lane white lines every 50-80m (Polyworks IMInspect) • Feature collection from pointclouds (Polyworks IMInspect) • 3D Modeling (TIN) from features and survey map creation (Autodesk Civil 3D) • Archiving for future reference: Subsampled pointclouds (5cm) per km (Polyworks IMView) “Korinthos – Tripoli” Highway

9. “Korinthos – Tripoli” Highway • Point cloud vs TIN model / features

10. Background survey map (scale 1:500) “Korinthos – Tripoli” Highway

11. Background survey map (scale 1:500) “Korinthos – Tripoli” Highway

12. Evaluation of tarmac deformations at the 4 airplane maneuver areas on either side of the E & W air-corridors Athens International Airport

13. Survey requirements • Positional accuracy: 1cm • Resolution: 5cm • Data capture for each area within 6 hours • Tarmac 3D modeling • Elevation maps (contour spacing: 2cm) • Cross-section level analysis Athens International Airport

14. Project tasks • 6 to 9 scan positions per area (scanner on top of a car, tripod mounted), 20% pan-tilt base overlap, distance between scans <50m • Georeference using conic and circular targets, measured from the airport’s geodetic control points • Creation of an aligned and georeferenced pointcloud for each area (Polyworks IMAlign and IMInspect) Athens International Airport

15. Project tasks • Subsampling (3cm) and triangulation of data points (Polyworks IMInspect), optimization and decimation of TIN model from 3 million triangles to <5000 triangles (Polyworks IMEdit, IMCompress) Athens International Airport

16. Project tasks • Creation of elevation map (contour spacing 2cm) (Autodesk Civil 3D) Athens International Airport

17. Project tasks • Cross section based analysis (ODOS software), reports • Evaluation of the results by the AIA authorities Athens International Airport

18. Evaluation of safety improvement measures in road intersections Ministry of Public Works – Maintenance Department Current intersection layout – orthophoto from pointcloud Design of improvementmeasures – 3D modeling

19. Evaluation of safety improvement measures in road intersections Ministry of Public Works – Maintenance Department • General layout fly-through Current layout Proposed layout

20. Evaluation of safety improvement measures in road intersections Ministry of Public Works – Maintenance Department • Driving simulation – Direction from Messolongi to Antirrio Current layout Proposed layout

21. Static Laser Scanning can be an efficient road mapping tool for projects that require: • high accuracy • significant level of detail • total object recording for archiving and future reference • 3D modeling and motion simulation • safe data collection • Disadvantages: • productivity for long objects (e.g. highways) cannot exceed 500 to 800m of surveyed road per day (portability and scanning height are critical factors) • significant post processing work is needed, decimation is required to export data to transportation design software • Mobile scanning systems with improved functionality will provide a much faster and efficient alternative in the near future Conclusions

22. Any questions? Visit: www.jgc.gr / www.astrolabe.gr