Proceedings International Workshop on Mobile Mapping Technology

li, rongxing

Bibliographic data

Monograph

Persistent identifier:: 856671290

Author:: Li, Rongxing

Title:: Proceedings International Workshop on Mobile Mapping Technology

Sub title:: April 21 - 23, 1999, Bangkok, Thailand

Scope:: 1 Online-Ressource (Getr. Zählung [ca. 400 Seiten])

Year of publication:: 1999

Place of publication:: London

Publisher of the original:: RICS Books

Identifier (digital):: 856671290

Illustration:: Illustrationen, Diagramme, Karten

Language:: English

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

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Monograph

Collection:: Earth sciences

Chapter

Title:: [Session 2: Mobile Mapping (2)]

Document type:: Monograph

Structure type:: Chapter

Chapter

Title:: TOWARDS AUTOMATED PROCESSING OF MOBILE MAPPING IMAGE SEQUENCES. C. Tao, M. A. Chapman, and N. El-Sheimy, B. Chaplin.

Document type:: Monograph

Structure type:: Chapter

2-5-8 The two 3D point sets, derived from each epoch, are then analyzed for temporal correspondence. This analysis is still currently under investigation. A linear, three-dimensional, least squares similarity transformation is proposed, in which the second 3D point set is transformed onto the first. The computed transformation parameters then represent the relative motion between exposures. More detailed description can refer to Chaplin and Chapman (1998). Tests on simulated and real data have shown the viability of the technique provide that the solution is appropriately constrained. 5. CONCLUSIONS The combination of computational vision and digital photogrammetry technologies is the principal methodology used throughout the thesis research. It is a key to the development and implementation of the three automated approaches. The thorough understanding of the imaging geometry and the extensive development of valid constraints constitute very important parts of our research work. A number of state-of-the- art computer vision methods, namely, model-driven feature extraction, multiple-image matching and shape from image sequences, are developed. Another methodology extensively applied is the human- computer collaborative semi-automatic scheme. An interesting aspect of the history of mankind is the relationship between human and computer. Although the great achievements have been made in recent 10 years, the realization of fully automatic feature extraction is still restricted especially in photogrammetry. Since we acknowledge that it is a long time before the automated feature extraction algorithm can be available as a production tool, and there is no much probability to separate the operator from the system, why should we not take the operator as a component of the system at the beginning of the system design? (Tao and Lin, 1994). A combination of the computational power of the computer and the interpretative ability and knowledge of the human brain has been implemented in the approaches of object measurement and extraction of vertical line features. It has been demonstrated that the use of this methodology makes the system work more reliably and efficiently. The following conclusions can be drawn based on the research results and real data tests: • The model-driven feature extraction methods have been proposed in the extraction of road centerline features and vertical line features. The geometric and photometric models of the specific features are established firstly. Then, the algorithms tailored to these models are designed. For example, in the extraction of centerline features, the algorithms of oriented edge detection, dual-edge detection and edge filtering by a new majority voting technique are developed. In the extraction of vertical line features, the algorithms of initial edge detection, edge thinning, vertically oriented edge detection, primary line grouping and secondary line grouping are implemented. • • The multinocular epipolar constraint has been successfully used to design an effective strategy of multiple-image matching. The matching ambiguities can be greatly reduced by using multiple-image matching associated with the weighted cross-correlation, the correlation coefficient analysis, the disparity range constraint, and the two-way matching double-check techniques. The method and its similar versions have been used in all these proposed approaches. It is seen that the method can be applied to not only point-feature correspondence, but also line-feature correspondence. More importantly, the accuracy and reliability of the 3-D reconstruction results can also be greatly improved using the multiple corresponding points or lines derived by the multiple-image matching method. • The concept and method of shape from image sequences are proposed and developed. This is, essentially, a closely coupled bottom-up and top-down reconstruction strategy. The whole reconstruction process is designed based on an interaction between a 3-D deformable model and updating information derived from the stereoscopic image sequences. This design leads to a robust result because the local and global shape of the model is controlled under the combinations of the actions of the internal energy (model) and the external energy (image). The synthesis of multiple constraints has been implemented by the least action principle, a physically-based mechanism for constraint combination. The advantages of the method are that constraints both from model assumptions and image sequences can be incorporated into a mathematical model, and the constraint combination can be solved by a Lagrangian motion equation. This approach represents a successful accommodation of multiple constraints from a mobile mapping system. • Image bridging is one of the new concepts in the development of mobile mapping systems. Current work involves the investigation of techniques for the automatic and robust establishment of correspondence between two 3D point sets, and techniques for verifying the correspondence, for example, back-projection and matching in image space. Following this, sequential position and orientation updating procedures will be applied. 6. THE FUTURE WORK • Image capture rate The stereo-motion cooperation based approach has demonstrated great advantages on the correspondence issue. If a high image capture rate is available, an improvement to a more robust matching can be achieved by using a fusion of feature correspondence and optical flow methods. • Image compression The fast image compression and communication techniques should be developed, due to the huge volume of image data generated. Data link from the mobile vehicle to an office GIS and data dissemination through internet/intranet should also be considered. • Multi-sensor information fusion It is believed that the automatic sensing ability will be greatly enhanced by using multi-sensor information, such as color, laser, and sonar. For example, if a laser ranging device is used and angled downward/forward the road, the elevation data of the road surface can be collected. This information can be further incorporated to improve the reliability of the automated methods. However, some issues have to be addressed, such as multiple information fusion, registration, management and computational complexity.

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