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Wang A.,Wuhan University | Wang A.,Key Laboratory of Precise Engineering and Industry Surveying | Zhang H.,Wuhan University | Wang X.,Wuhan University | Shang X.,Wuhan University
Journal of Geomatics | Year: 2017

Because of the measuring mechanism and operating mode of side-scan sonar system, it is hard to obtain the exact position of tow-fish, which also makes the side-scan sonar image only used for the qualitative analysis, but ignored its fine processing work. In order to solve the distortion problem of side-scan sonar waterfall image, a systematic study about processing principles of side-scan sonar data, including seabed line tracing, slant distance correction, tow-fish position calculation, geocoding mosaic and gap filling, is carried out in this paper. In the end, a high-quality relief, with less distortion, intuitive coordinate, clean outline, uniform gray level is built. © 2017, Wuhan University. All rights reserved.

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.

Shi J.,Wuhan University | Shi J.,Key Laboratory of Precise Engineering and Industry Surveying | Yuan X.,Wuhan University | Yuan X.,Collaborative Innovation Center for Geospatial Technology | And 2 more authors.
GPS Solutions | Year: 2016

We extend the application of real-time kinematic PPP to aerial triangulation using GPS to determine coordinates of the antenna installed on the airplane, using real-time satellite products from IGS and the CNES Analysis Center. In order to verify the performance of real-time kinematic PPP for aerial triangulation, three tests with varying aerial and ground conditions are assessed. Numerical results show that real-time kinematic PPP using IGS real-time products of 5-cm orbit accuracy and 0.1- to 0.3-ns clock precision can provide comparable accuracy for aerial photogrammetric mapping at the scale of 1:1000 as does post-mission kinematic PPP using IGS final products. Millimeter-to-centimeter-level differences and centimeter-to-2-decimeter differences are identified for horizontal and vertical coordinates of ground check points, respectively, in the three tests. The comparison between real-time IGS and CNES products for GPS positioning and aerial triangulation unveils that real-time products with a better clock precision can result in better performance of GPS real-time kinematic PPP as applied to aerial triangulation. © 2016 Springer-Verlag Berlin Heidelberg

Shi J.,Hubei University | Shi J.,Key Laboratory of Precise Engineering and Industry Surveying | Xu C.,Hubei University | Xu C.,Key Laboratory of Precise Engineering and Industry Surveying | And 2 more authors.
Journal of Geodesy | Year: 2015

Global Positioning System (GPS) has become a cost-effective tool to determine troposphere zenith total delay (ZTD) with accuracy comparable to other atmospheric sensors such as the radiosonde, the water vapor radiometer, the radio occultation and so on. However, the high accuracy of GPS troposphere ZTD estimates relies on the precise satellite orbit and clock products available with various latencies. Although the International GNSS Service (IGS) can provide predicted orbit and clock products for real-time applications, the predicted clock accuracy of 3 ns cannot always guarantee the high accuracy of troposphere ZTD estimates. Such limitations could be overcome by the use of the newly launched IGS real-time service which provides ∼5 cm orbit and 0.2–1.0 ns (an equivalent range error of 6–30 cm) clock products in real time. Considering the relatively larger magnitude of the clock error than that of the orbit error, this paper investigates the effect of real-time satellite clock errors on the GPS precise point positioning (PPP)-based troposphere ZTD estimation. Meanwhile, how the real-time satellite clock errors impact the GPS PPP-based troposphere ZTD estimation has also been studied to obtain the most precise ZTD solutions. First, two types of real-time satellite clock products are assessed with respect to the IGS final clock product in terms of accuracy and precision. Second, the real-time GPS PPP-based troposphere ZTD estimation is conducted using data from 34 selected IGS stations over three independent weeks in April, July and October, 2013. Numerical results demonstrate that the precision, rather than the accuracy, of the real-time satellite clock products impacts the real-time PPP-based ZTD solutions more significantly. In other words, the real-time satellite clock product with better precision leads to more precise real-time PPP-based troposphere ZTD solutions. Therefore, it is suggested that users should select and apply real-time satellite products with better clock precision to obtain more consistent real-time PPP-based ZTD solutions. © 2015, Springer-Verlag Berlin Heidelberg.

Shi J.,Wuhan University | Shi J.,Key Laboratory of Precise Engineering and Industry Surveying | Xu C.,Wuhan University | Xu C.,Key Laboratory of Precise Engineering and Industry Surveying | And 3 more authors.
IEEE Transactions on Geoscience and Remote Sensing | Year: 2015

GPS-based precipitable water vapor (PWV) estimation has been proven as a cost-effective approach for numerical weather prediction. Most previous efforts focus on the performance evaluation of post-processed GPS-derived PWV estimates using International GNSS Service (IGS) satellite products with at least 3-9-h latency. However, the suggested timeliness for meteorological nowcasting is 5-30 min. Therefore, the latency has limited the GPS-based PWV estimation in real-time meteorological nowcasting. The limitation has been overcome since April 2013 when IGS released real-time GPS orbit and clock products. This becomes the focus of this paper, which investigates real-time GPS precise point positioning (PPP)-based PWV estimation and its potential for rainfall monitoring and forecasting. This paper first evaluates the accuracy of IGS CLK90 real-time orbit and clock products. Root-mean-square (RMS) errors of < 5 cm and ∼0.6 ns are revealed for real-time orbit and clock products, respectively, during July 4-10, 2013. Second, the real-time GPS PPP-derived PWV values obtained at IGS station WUHN are compared with the post-processed counterparts. The RMS difference of 2.4 mm has been identified with a correlation coefficient of 0.99. Third, two case studies, including a severe rainfall event and a series of moderate rainfall events, have been presented. The agreement between the real-time GPS PPP-derived PWV and ground rainfall records indicates the feasibility of real-time GPS PPP-derived PWV for rainfall monitoring. Moreover, the significantly reduced latency demonstrates a promising perspective of real-time GPS PPP-based PWV estimation as an enhancement to existing forecasting systems for rainfall forecasting. © 1980-2012 IEEE.

Ding S.,Wuhan University | Ding S.,Key Laboratory of Precise Engineering and Industry Surveying | He L.,Hunan City University | Li P.,Wuhan Geomatic Institute
Wuhan Daxue Xuebao (Xinxi Kexue Ban)/Geomatics and Information Science of Wuhan University | Year: 2016

Foundation and rail construction must meet higher accuracy for high-speed railway, in order to effectively control projection distance deformation of a GPS control network and reduce the number of projection zone for the east-west highspeed railways, this paper discusses the processing method for the oblique Mercator projection to be applied to develop uniform plane coordinate system by the basic theoriessuch as ellipsoid transformation, projection from ellipsoid to sphere and spherical cylindrical projection. Through a practical engineering example analysis, we show that the oblique Mercator projection can control the length deformation and meet the 10ppm length deformation per kilometer for control network of nonballasted-track and 25ppm for ballast track, and avoid the divisions of too many projection zones. Comparing withnormal Gaussian projection the oblique Mercator projectionhas more superiorities on the east-west high-speed railway andother route engineering control networks. © 2016, Wuhan University All right reserved.

Xu Y.,Wuhan University | Xu Y.,Key Laboratory of Precise Engineering and Industry Surveying | Zhou J.,Wuhan University | Zhou J.,Key Laboratory of Precise Engineering and Industry Surveying | And 2 more authors.
IEEE Communications Letters | Year: 2014

In this letter we present a novel method for source node localization using received signal strength in situations where path-loss model parameters are unknown. First, a ratio approach is used to eliminate the transmitting power uncertainty, then, combined with a search method for path-loss exponent under certain constraints, linear least squares is utilized to determine the location of the source node. Simulations are used to demonstrate the feasibility and suitability of the proposed method. The simulation results indicate that the method presented outperforms other off-the-shelf source node localization algorithms intended for use when path-loss model parameters are unknown. © 2014 IEEE.

Ding S.,Wuhan University | Ding S.,Key Laboratory of Precise Engineering and Industry Surveying | Jiang W.,Wuhan University
Wuhan Daxue Xuebao (Xinxi Kexue Ban)/Geomatics and Information Science of Wuhan University | Year: 2014

The linear semiparametric regression model L=BX+s+Δ is a combine of classical linear model with nonparametric regression model. Based on the basic theory of the penalized least squares for the semiparametric mode, this paper presents a detailed discussion on the theory and method of hypothetical test for nonparameters in the linear semiparametric model and the hypothetical test statistics are derived and its distribution are proved. Finally the validity of the proposed theory and method of the hypothetical test for nonparameter is confimed by simulated experiment. ©, 2014, Wuhan University. All right reserved.

Xiang D.,Wuhan University | Xiang D.,Key Laboratory of Precise Engineering and Industry Surveying | Gong J.,Hubei Qingjiang Hydroelectric Development Co.
Wuhan Daxue Xuebao (Xinxi Kexue Ban)/Geomatics and Information Science of Wuhan University | Year: 2014

Wavelet decomposition scale is directly related to the effect of de-noising. To de-noising of deformation sequence, the authorcombines the information criterion of the time series analysis modeling pricing and the characteristics of Gauss white noise under the wavelet transform, put forward the method thatthe Akaike information criterion was used as quantitativeindex to determine the optimal decomposition scale. The calculation results of examples show that in the Akaike information criterion calculated value to the Minimum, the decomposition scale determinedconform to the distribution of signal-to-noise, de-noising effect is better, and Akaike information criterion was used as quantitative index to determine the optimal decomposition scale is effective, itimprove the convenience of wavelet de-noising in deformation data processing.

Zhang Z.,Wuhan University | Zhang Z.,Key Laboratory of Precise Engineering and Industry Surveying
Journal of Geomatics | Year: 2014

From the definition of engineering geodesy departure, the development history of engineering measurements is described combining with typical historical data. It is discussed that the relations of development status by engineering geodesy with the rapid progress and great development of science and engineering construction in nearly half a century. The development direction and character of this discipline are pointed out. Development trend of engineering geodesy is proposed. It is prospected that engineering geodesy will be further developed to the macro and micro aspects.

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