Time filter

Source Type

Chen Y.,Central South University | Yi Z.,Central South University | Yi Z.,Key Laboratory for Urban Geomatics of National Administration of Surveying | Kuang C.,Central South University | Dai W.,Central South University
Wuhan Daxue Xuebao (Xinxi Kexue Ban)/Geomatics and Information Science of Wuhan University | Year: 2016

Ambiguity resolution is one of the key technologies for high precision GPS positioning. Accelerating ambiguity fixing can expand the application and improve the reliability of GPS positioning. Based on the characteristics of single-frequency GPS kinematic positioning, a new method to accelerate ambiguity fixing is proposed in this paper. First, a receiver and epoch double differenced approach was used to get the epoch-differenced coordinate information between neighbouring epochs. Then, the epoch-differenced coordinate information is combined with the ambiguity normal equation. Adding epoch-differenced coordinate information to the ambiguity normal equation can decrease the ill-posed-ness of the normal equation, so the accuracy of the floating ambiguity solution was improved and the convergence time of ambiguity was shortened. Experimental results show that the new method can accelerate ambiguity resolution in GPS relative kinematic positioning with good application value. © 2016, Research and Development Office of Wuhan University. All right reserved.

Zhang X.,Beijing University of Civil Engineering and Architecture | Zhang X.,Key Laboratory for Urban Geomatics of National Administration of Surveying | Kang S.,Beijing BSH e learing Co. | Hou M.,Beijing University of Civil Engineering and Architecture | Liu X.,Beijing University of Civil Engineering and Architecture
International Journal of Emerging Technologies in Learning | Year: 2015

With the rapid development of network technology, large enterprises have established their own online learning and examination systems, respectively. However, those network examination systems are dispersive, closed and disconnected, so resources cannot be utilized in a balanced way, which may cause substantial waste of enterprise resources. To solve such a problem, emerging cloud computing technology with service on demand characteristics and dynamic expansion capability provides the possibility of a shared network examination system, known as a cloud exam support service, with lower costs. A feasible solution for the application of the cloud computing technology in the network examination that combines the theoretical analysis, system design and technical implementation is put forward in this paper. The design, development, and pilot application of the cloud examination system described in this paper show that this study is highly practical, operable, and worthy of application and popularization.

Zhu L.,Beijing University of Civil Engineering and Architecture | Zhu L.,Key Laboratory for Urban Geomatics of National Administration of Surveying | Shortridge A.M.,Michigan State University | Lusch D.,Michigan State University
Journal of Applied Remote Sensing | Year: 2012

Light detection and ranging (LiDAR) point cloud data can contain millions of point returns from a diverse range of surface features, and directly reconstructing buildings from these data is challenging. Trees and other vegetation pose a particular problem in many built environments. This paper investigates several efficient procedures for detecting buildings and excluding vegetation using LiDAR and imagery data. Two general approaches for identifying and filtering out returns from vegetation are investigated: the first uses a normalized difference vegetation index (NDVI) image, while the second uses height differences. The utility of an entropy filter for improving NDVI filter performance as well as two distinct approaches for height-difference modeling are also evaluated. All methods use efficient raster-based algorithms for filtering while retaining the high spatial precision of the vector LiDAR point returns. Following removal of nonbuilding points, remaining points are segmented into distinct building features. In addition, we place particular emphasis on the analysis of processing challenges and special cases as well as the accuracy of these different methods on a large-volume LiDAR dataset covering a challenging build environment. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).

Huang J.,Hubei University | Huang J.,Key Laboratory for Urban Geomatics of National Administration of Surveying | Xing C.,Hubei University | Xing C.,Key Laboratory of Precise Engineering and Industry Surveying
Electronics, Communications and Networks IV - Proceedings of the 4th International Conference on Electronics, Communications and Networks, CECNet2014 | Year: 2015

The problem of crack detection in buildings can be realized by using infrared thermal imaging technology, which is based on the non-contact detection of temperature observation. In this paper, image processing methods of infrared images are described. In addition, a simulation experiment on a building which locates in Wuhan is held to examine the reliability of the methods, and the results show that the theory and methods in this paper have practical significances and can be used for detecting cracks of buildings. © 2015 Taylor & Francis Group, London.

Hwang J.,Sungkyunkwan University | Yun H.,Sungkyunkwan University | Jeong T.,Sungkyunkwan University | Suh Y.,Pukyong National University | And 2 more authors.
Remote Sensing | Year: 2013

This paper focuses on the use of the Land-based Mobile Mapping System (LMMS) for the unscheduled updates of a National Base Map, which has nationwide coverage and was made using aerial photogrammetry. The objectives of this research are to improve the weak points of LMMS surveying for its application to the updates of a National Base Map (NBM), which has rigorous accuracy and quality standards. For this, methods were suggested for the (1) improvement of the accuracy of the Global Positioning System/Inertial Navigation System (GPS/INS) in the long-term exposure of environments with poor GPS reception; (2) elimination of mutual deviations between LMMS data obtained in duplicate to meet resolution standards; (3) devising an effective way of mapping objects using LMMS data; and (4) analysis of updatable regions and map layers via LMMS. To verify the suggested methods, experiments and analyses were conducted using two LMMS devices in four target areas for unscheduled updates of the National Base Map. © 2013 by the authors.

Discover hidden collaborations