Systems for data processing, anaylsis and representation

Allam, Mosaad; Plunkett, Gordon

Bibliographic data

Monograph

Persistent identifier:: 1067490280

Title:: Systems for data processing, anaylsis and representation

Sub title:: ISPRS Commission II Symposium : June 6 - 10, Ottawa, Canada

Scope:: 1 Online-Ressource (XX, 530 Seiten)

Year of publication:: 1994

Place of publication:: Ottawa

Publisher of the original:: The Surveys, Mapping and Remote Sensing, Natural Resources Canada

Identifier (digital):: 1067490280

Illustration:: Illustrationen

Signature of the source:: ZS 312(30,2)

Language:: English

Additional Notes:: Erscheinungsdatum des Originals ist aus dem Copyrightjahr ermittelt.

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: Allam, Mosaad; Plunkett, Gordon

Corporations:: Symposium Systems for Data Processing, Analysis and Representation, 1994, Ottawa; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Instrumentation for Data Reduction and Analysis; Kanada, Surveys, Mapping and Remote Sensing Sector

Adapter:: Symposium Systems for Data Processing, Analysis and Representation, 1994, Ottawa; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Instrumentation for Data Reduction and Analysis; Kanada, Surveys, Mapping and Remote Sensing Sector

Founder of work:: Symposium Systems for Data Processing, Analysis and Representation, 1994, Ottawa; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Instrumentation for Data Reduction and Analysis; Kanada, Surveys, Mapping and Remote Sensing Sector

Other corporate:: Symposium Systems for Data Processing, Analysis and Representation, 1994, Ottawa; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Instrumentation for Data Reduction and Analysis; Kanada, Surveys, Mapping and Remote Sensing Sector

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2019

Document type:: Monograph

Collection:: Earth sciences

Chapter

Title:: [Friday, June 10, 1994]

Document type:: Monograph

Structure type:: Chapter

Chapter

Title:: [Session L-1 WG II/1 - Real-Time Mapping Technologies - Algorithmic Aspects]

Document type:: Monograph

Structure type:: Chapter

Chapter

Title:: LASER RANGE SCANNER SUPPORTING 3-D RANGE AND 2-D GREY LEVEL IMAGES FOR TUNNEL SURFACE INSPECTION C. Fröhlich, M. Mettenleiter and G. Schmidt

Document type:: Monograph

Structure type:: Chapter

de la je la o les caphie d'une S et j""Sur | dans | type S; En piéce fier e et Nous nt de 5. L2 Cette 29g S0 zone nt le ^ pour rement te le ses je des és en le ces é ont LASER RANGE SCANNER SUPPORTING 3-D RANGE AND 2-D GREY LEVEL IMAGES FOR TUNNEL SURFACE INSPECTION C. Frôhlich, M. Mettenleiter and G. Schmidt Laboratory of Automatic Control Engineering Technical University of Munich, D-80290 Munich, Germany KEY WORDS: range sensor, range finders, cw lasers, range data, integration, tunnel inspection ABSTRACT For the survey and inspection of buildings, tunnels or underground canals, a non-tactile, robust and precise imaging of height and depth profiles is a basis sensor technology. For visual inspection, surface classification, and documentation purposes, however, additional information concerning reflectance of measured objects is necessary. High-speed acquisition of both geometric and visual information is achieved by means of an eyesafe laser range scanner, supporting consistent range and grey level profiles which are similar to video images. This paper reports the optical, electronic and mechanical system design of the scanner, its information processing system inclu- ding dedicated signal processors, and a transputer network for sensor data processing. The paper discusses experimental results of the laser range scanner with respect to noise as well as its long-term stability, and accuracy. Finally, results from tunnel surface inspection with the laser range scanner are presented. 1. INTRODUCTION Range sensing is a crucial component of automation in indus- trial processes. To realize robotic systems [1,2] for manu- facturing, handling, transportation and inspection tasks, how- ever, it is the only way to provide the system with three di- mensional information [3] of its environment. The classical computer vision approach to range sensing is to use passive techniques such as stereo-vision or motion stereo. However, those techniques are not yet sufficiently reliable or fast enough to be used in many applications, most notably real- time robotic or inspection systems. Active sensors, which generate the illumination instead of using only the ambient il- lumination, have received increasing attention as a viable alternative to passive sensors, featuring direct access to range information in real-time. Their importance was recognized relatively early. For example, Besl [4] examines a wide variety of active range imaging technologies, comparing them quantitatively by evaluating a figure of merit based on range accuracy, field of view, and image acquisition time. A review of using range sensing devices in autonomous navigation of mobile robots can be found in Hebert ([5], Everett [6], Elfes [7] and Rozmann[8]. Nitzan et al. [9] describe a system inter- preting indoor scenes by use of range and intensity information from a laser ranging system. Through the framework of SFB 331 "Information Processing in Autonomous Mobile Robots", a 3-D laser range camera [10,11,12] was developed for indoor vehicle and robotic ap- plications. The laser range camera is an optical-wavelength radar system, and is comparable to devices built by Erim [13], Odetics [14], and Perceptron [15], measuring the range between sensor and target surface as well as the reflectance of the target surface which corresponds to the magnitude of the back scattered laser energy. In contrast to these range sensing devices, the laser camera under consideration is designed for eyesafe operation, emitting a minimum of near-infrared laser energy. For surface inspection of railway and highway tunnels how- ever, the performance of the range measuring system of the laser camera was improved with a look towards robustness, range accuracy, and range precision. This paper reports design and practical details of the laser range scanner for tunnel surface inspection. Chapter 2 out- lines the performance requirements with tunnel surface inspection and introduces the measurement principle of the sensor. Hardware design of the laser range scanner, including the main modules, such as the laser head with transmitter and receiver electronics, high frequency unit, laser beam deflec- tion system, and digital signal processing unit are discussed in Chapter 3. The signal processing unit consists of dedicated signal processors and a transputer system for real-time sensor data processing. Chapter 4 focuses on statistical evaluation of range data, including noise, drift over time, precision, and accuracy with range measurements. It discusses the influences of ambient light, surface material of the target, and ambient temperature for range accuracy and range precision. Furthermore, experimental results from the inspection of tunnel surfaces are presented. Chapter 5 concludes the paper by summarizing its results and gives a short outlook to future work in the tunnel surface inspection project. 2. DESIGN ASPECTS 2.1 Performance requirements With railway tunnel inspection, the precise measurement of the tunnel tube geometry, tracks and contact wires (Fig. 3a) is essential in order to hold tolerances for safe passing of trains. Furthermore, detection of possible cracks (even capillary cracks) in the tunnel surface is important in order to initiate repair work of the tunnel tube in time. For tunnel inspection, measurement of 360° profiles while navigating through the tunnel tube is more sufficient than measuring 3-D images. To meet these demands, high spatial resolution, accurate and 471

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