Abstract
The need for reliable systems for capturing precise detail in tunnels has increased as the number of tunnels (e.g., for cars and trucks, trains, subways, mining and other infrastructure) has increased and the age of these structures and, subsequent, deterioration has introduced structural degradations and eventual failures. Due to the hostile environments encountered in tunnels, mobile mapping systems are plagued with various problems such as loss of GNSS signals, drift of inertial measurements systems, low lighting conditions, dust and poor surface textures for feature identification and extraction. A tunnel mapping system using alternate sensors and algorithms that can deliver precise coordinates and feature attributes from surfaces along the entire tunnel path is presented. This system employs image bridging or visual odometry to estimate precise sensor positions and orientations. The fundamental concept is the use of image sequences to geometrically extend the control information in the absence of absolute positioning data sources. This is a non-trivial problem due to changes in scale, perceived resolution, image contrast and lack of salient features. The sensors employed include forward-looking high resolution digital frame cameras coupled with auxiliary light sources. In addition, a high frequency lidar system and a thermal imager are included to offer three dimensional point clouds of the tunnel walls along with thermal images for moisture detection. The mobile mapping system is equipped with an array of 16 cameras and light sources to capture the tunnel walls. Continuous images are produced using a semi-automated mosaicking process. Results of preliminary experimentation are presented to demonstrate the effectiveness of the system for the generation of seamless precise tunnel maps.
Highlights
This paper focuses on the estimation of reliable three dimensional coordinates, geometric forms and non-spatial attributes of features in harsh environments such as tunnels
The need for reliable systems for capturing precise detail in tunnels has increased as the number of tunnels has increased and the age of these structures and, subsequent, deterioration has introduced structural degradations and eventual failures (Gordon and Lichti, 2007, Hashimoto et al, 2006, Ioannidis et al, 2006, Masoto et, 2007 and 2008, Monserrat and Crosetto, 2008, Stiros and Kontogianni,2009, Tsakiri et al, 2006)
Due to the hostile environments encountered in tunnels, mobile mapping systems are plagued with various problems such as loss of GNSS signals, drift of inertial measurements systems, low lighting conditions, dust and poor surface textures for feature identification and extraction
Summary
This paper focuses on the estimation of reliable three dimensional coordinates, geometric forms and non-spatial attributes of features in harsh environments such as tunnels. Lower cost systems in the form of micro electromechanical systems (MEMS) have been employed to bridge the gap between cost and the delivery of reliable orientation information. While these small form factor IMUs have found application in various scenarios, they suffer from various sensitivities such as high drift rates, vulnerability to temperature changes and susceptibility to low grade electrical, magnetic and mechanical loadings. Distance measurement instruments (DMI), lasers and range cameras Each of these sensor types suffers from various shortcomings when used for positioning and orientation estimation (Abellan et al, 2009 and 2011, Buckley et al, 2008, Burton et al, 2010, Dekker et al, 2008, Fekete et all, 2010 and 2012)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
