Report No. UT-20.18 ASSESSING CLOSE-RANGE PHOTOGRAMMETRY AS AN ALTERNATIVE TO LIDAR TECHNOLOGY AT UDOT DIVISIONS Prepared For: Utah Department of Transportation Research & Innovation Division Final Report August 2020 DISCLAIMER The authors alone are responsible for the preparation and accuracy of the information, data, analysis, discussions, recommendations, and conclusions presented herein. The contents do not necessarily reflect the views, opinions, endorsements, or policies of the Utah Department of Transportation or the U.S. Department of Transportation. The Utah Department of Transportation makes no representation or warranty of any kind, and assumes no liability therefore. ACKNOWLEDGMENTS The authors acknowledge the Utah Department of Transportation (UDOT) for funding this research, and the following individuals from UDOT on the Technical Advisory Committee for helping to guide the research: • Vincent Liu • Abdul Wakil • Kaitlin Marousis • Michael Butler • Paul Wheeler • Chris Whipple • Nathan Jones • Trevor Egan i TECHNICAL REPORT ABSTRACT 1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. UT-20.18 N/A N/A 4. Title and Subtitle 5. Report Date Assessing Close-Range Photogrammetry as an Alternative for LiDAR June 2020 Technology at UDOT Divisions 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. Chandler Cross, Mohammad Farhadmanesh, Abbas Rashidi 9. Performing Organization Name and Address 10. Work Unit No. The University of Utah 5H08480H Department of Civil and Environmental Engineering 11. Contract or Grant No. 201 Presidents Circle 20-8083 Salt Lake City, Utah 84112 12. Sponsoring Agency Name and Address 13. Type of Report & Period Covered Utah Department of Transportation Final 4501 South 2700 West August 2019 to October 2020 P.O. Box 148410 14. Sponsoring Agency Code Salt Lake City, UT 84114-8410 UT19.601 15. Supplementary Notes Prepared in cooperation with the Utah Department of Transportation and the U.S. Department of Transportation, Federal Highway Administration 16. Abstract LiDAR (Light Detection and Ranging) is a mature and efficient technology currently used by various divisions of UDOT (asset management, traffic control, pavement, construction, etc.). Some of the current applications of LiDAR at UDOT (as well as other DOTs) include: asset management for roads and buildings, quality control of pavements and other infrastructure surfaces, 3D as-built documentation of constructed facilities, etc. While effective, there are some limitations in using LiDAR as a common engineering tool: The technology is pretty expensive, certain levels of expertise and training are required to use LiDAR scanners for data collection and processing results, and finally it might not be available for all units and individuals. Close-range photogrammetry is another emerging technology that could be considered as a potential alternative for LiDAR scanning devices. The technology is based on processing images and videos simply captured by off-the-shelf cameras or smartphones. Unlike LiDAR, close-range photogrammetry is very cost effective, simple, and easy-to-use. There is no need for extra hardware settings and almost everyone has a smartphone or camera so collecting and processing data is very feasible. Within the last decade, several software packages in the area of close-range photogrammetry have been introduced for research, education, and commercial purposes. Some examples are Autodesk Recap; Agisoft Photoscan; 3DF Zephyr; VisualSFM; and Photomodeler. The outputs of both LiDAR and Photogrammetric technologies are in the form of dense point clouds. While the output of the two methods are similar, there might be differences in level of accuracy and density of the generated point clouds. In addition, each method might work differently under certain conditions such as scanning shiny and reflective objects, sharp edges, etc. Despite the increasing popularity of close-range photogrammetry, it has not been considered as a practical scanning tool by UDOT divisions yet. This project aims to address this important issue by exploring the feasibility of using this technology for various applications currently handled by LiDAR at UDOT. 17. Key Words 18. Distribution Statement 23. Registrant's Seal Photogrammetry, LiDAR, 3D Reconstruction Not restricted. Available through: UDOT Research Division N/A 4501 South 2700 West P.O. Box 148410 Salt Lake City, UT 84114-8410 www.udot.utah.gov/go/research 19. Security Classification 20. Security Classification 21. 97 22. Price (of this report) (of this page) N/A Unclassified Unclassified ii TABLE OF CONTENTS LIST OF TABLES ......................................................................................................................... vi LIST OF FIGURES ....................................................................................................................... vi UNIT CONVERSION FACTORS ................................................................................................ ix LIST OF ACRONYMS .................................................................................................................. x EXECUTIVE SUMMARY .......................................................................................................... 11 1.0 INTRODUCTION .................................................................................................................. 12 1.1 Introduction ..........................................................................................................................12 1.2 Problem Statement ...............................................................................................................14 1.3 Objectives ............................................................................................................................16 1.4 Scope ....................................................................................................................................16 1.5 Outline of Report .................................................................................................................17 2.0 RESEARCH METHODS ....................................................................................................... 17 2.1 Background ..........................................................................................................................17 2.1.1 Laser Scanners ..............................................................................................................17 2.1.2 Photo/Videogrammetry .................................................................................................19 2.1.3 Laser Scanners and Photogrammetry in Construction ..................................................20 2.2 Accuracy and Quality Measurement Methods .....................................................................21 2.3 Comparison Methods ...........................................................................................................22 2.4 Summary ..............................................................................................................................24 3.0 DATA COLLECTION ........................................................................................................... 24 3.1 Overview ..............................................................................................................................24 3.2 Roadway Asset Management ...............................................................................................25 3.2.1 Data Acquisition Camera ..............................................................................................25 3.2.2 Camera Settings and Mounting Procedures ..................................................................29 3.2.3 LiDAR Data Collections ...............................................................................................30 3.3 Pedestrian Access Ramp Data Collections ..........................................................................31 3.3.1 Pedestrian Access Ramp Inspections ............................................................................31 3.3.2 Data Collection and Camera Settings for Image Based Reconstruction .......................32 3.3.3 LiDAR Data Collection ................................................................................................33 iii 4.0 DATA EVALUATION .......................................................................................................... 34 4.1 Overview ..............................................................................................................................34 4.2 Roadway Asset Management ..............................................................................................35 4.2.1 Accuracy assessment and Quality Assessment .............................................................41 4.2.2 Model 1 .........................................................................................................................42 4.2.3 Model 2 .........................................................................................................................44 4.2.4 Model 3 .........................................................................................................................47 4.2.5 Model 4 .........................................................................................................................50 4.2.6 Model 5 .........................................................................................................................54