1. Land Based Laser Scanning Applications for Transportation Construction Projects Edward Jaselskis, Ph.D., P.E. Iowa State University

2. Agenda n Overview of Laser Scanning Technology n Pilot Study of Applications for Transportation Projects n Video Demonstration

3. An Overview of 3D Laser Scanning Technology

4. Overview n Why Laser Scanning? n Cyra System n Basic Concept n Major Procedures n Advantages n Applications

5. Why Laser Scanning? Poor As-built Info => Poor Retrofit Design  Higher project costs n Construction Industry Study: >5% – 15%  Missed schedules  Operations & maintenance inefficiencies and problems  Safety problems

6. Laser Scanner Electronics & Power Supply Laptop Computer Cyrax System

7. > 2000 points/sec 40ºx40º Field-of-view Cyclone 4.0 Scan Cloud Processing Software Cyrax 2500 2-6 mm Accuracy 1-150 m Scanning range Basic Concept of Laser Scanning

8. Up to 150m range (50m recommended) Eye-safe Class 2 Basic Concept of Laser Scanning

9. Scan Step 1: Target the Structure

10. Scan Step 2: Scan the Scene => Create a Point Cloud

11. Scan Step 3: Color the Points

12. Scan Step 4: Complex-Meshing Surfaces

13. Register Scans Together & Create Visual Database

14. Create Detailed 3D Model

15. 2D Plan, Elevation, Section Views

16. Accurate, complete, fast measuring, safe… Integrated modeling 2D / 3D CAD Advantages “point clouds” Export to CAD or use Virtual Surveyor

17. Applications n As-built drawings of Bridges, Industrial Plants, and Monuments n Rock Quantity Surveys n Freeway Redesign n Movie Animations

18. A Pilot Study on 3D Laser Scanning for Transportation Projects

19. outline n Objectives n Methodology n Field Operation n Data Processing n Project Results n Benefits and Conclusions

20. Objectives of Pilot Study n Determine Safety & Efficiency of Laser Scanning Technology for Iowa DOT n Determine Cost Saving and Accuracy of various applications

21. Methodology Identify Possible Projects Establish Goals Software Training Scan Objects in Field 3D Image Processing Comparison to other Technologies Benefits and Recommendations

22. Intersection (Lincoln Way & Grand Ave, Ames) Railway Bridge (Grand Ave, Ames) I-235 (500m) (Des Moines) Broadway Bridge (Des Moines) New Pavement (HW 5, Des Moines) Bridge Camber (HW520, Hardin) Stockpile (Hardin) Borrow Pit (I-235&80) Pilot Projects Training Elevation Smoothness Beam Camber Volume As Built DWG

23. Field Operations Surveying Scanning

24. Lesson Learned in the Field n Scanner Resolution n Battery Management n Sun Glare n Cabling n Target Overlap n Acquiring Targets n Vibration

25. Data Processing n Importing Coordinates n Registration n Fitting and Editing n Meshing n Contouring n Virtual Surveying

26. Analysis and Facts Pilot Projects Section of Highway Pair of Bridges New Concrete Pavement Bridge Beams StockpileBorrow Pit Importing coordinatesXXXX*XX RegistrationXXXXXX Fitting and editingXXXXX Mesh editingXXXXX ContouringXXX Using virtual surveyorXXXX ExportingXXXX 2D drawingX No. of Scans181235317 No. of Valid Scans171234317 Coordinate control problems Many NoneFewNoneMany Amount of cleanup required Substantial LessAverage Less Extra proceduresYes

27. Coordinates System n Coordinate File must be Imported into the Scan Database Before any Registration was Started n The Coordinate Unit, Three Coordinates Values and Coordinate File Format must be determined

28. Registration n Understand the Scanning Process n Match Images Together n Three Step Process:  Target Registration  Registration to Survey Data  Object Registration (Scanworlds)

29. Fitting & Editing n Images Scanned from Field May Contain Some Unnecessary Data n The noise needs to be removed n Major Steps Involved:  Segmenting  Region Growing  Editing

30. Fitting & Editing n Example of Region Growing

31. Fitting & Editing n Example of Fitted Point Clouds

32. Meshing n Creating a mesh can make point cloud more manageable n Different types of mesh available (TIN, Complex, etc.) n Major Steps  Mesh creation  Mesh editing  Mesh decimation

33. Contours and Lines Drawing n Reference Plane n Cut Plane n Contours n Export to Micro Station n Measure the volume

34. Measuring

35. Virtual Surveyor n Easy to obtain information w/o physically being on site n Pick coordinates, assign notes, and export data n Major Steps:  Create a file  Select points  Export data

36. Concerns and Special Features n Targets with acquisition problems  Larger errors happened beyond 50 meter  Different targets with same ID number n Checking and measuring target locations and distances in control space  Most of target errors ranged from 0 to 7 mm n New coordinate system needed to measure non- typical shape elevation n Multiple meshes needed to measure the volume

37. Concerns and Special Features n Example of poor registration

38. Project Results n Technical Results I-235 Elevation Stockpile Volume Beam Camber Result Limitations n Time Requirements n Cost Comparison

39. Major Technical Results n I-235 Elevation Measurement  Laser scanning is more accurate than Helicopter Photogrammetry

40. Major Technical Results n Stockpile Volume  507.07 cubic meters by laser scanning  512.96 cubic meters by GEOPAK with traditional surveying  Only 1.2% difference

41. Major Technical Results n Bridge Beam Camber  Rapid Calculation and reasonable accuracy

42. Result Limitations n Pavement Smoothness  Smoothness Measurement within instrument accuracy limits n Borrow Pit  Targeting Error

43. Time Requirements n Time Per Scan  Field time = 3.5~4.0 hrs (average 3.7 hrs)/8 = 28 minutes  Lab analysis = 1.3 ~ 10.5 hrs (average 2.5 hrs)/1 person = 2.5 hrs  Final Lab Trial = 0.3 ~ 1.6 hrs (average 0.8 hrs)/1 person = 48 minutes Note: Field time assumes an 8 person crew (2 scanner and 6 surveyors)

44. Cost Comparison for I-235

45. Benefits n Safer: No surveyors required on roadway n Less Disruption  No road closures required  Survey can occur with traffic n Collect design data quickly and accurately n Provides accurate assessment of soil and rock quantities n Cost comparable to slightly higher than other methods

46. Conclusion n Laser Scanning has application for Transportation Design and Construction n On-going hardware/software modifications will make this approach even competitive

47. A Video Demonstration on 3D Laser Scanning