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Fang J.,East China University of Technology | Fang J.,Key Laboratory of Watershed Ecology and Geographical Environment Monitoring | Liu H.,East China University of Technology | Zhang L.,East China University of Technology | And 3 more authors.
Computers and Electrical Engineering | Year: 2016

This paper presents a convex variational model for multiphase image segmentation by incorporating a multiresolution approach. We extend our previous work to formulate the energy functional which is robust response to image variations. In contrast to our previous work, which can lead to local minima, a global solution is proposed to minimize the segmentation energy with some constraint conditions. By incorporating edge-based information, a non-convex energy functional is first introduced on the membership functions, which are used as indicators of different homogeneous regions. Then the non-convex problem is converted into a continuous convex formulation. An efficient dual minimization implementation of our binary partitioning function model accurately describes disjoint regions using stable segmentation. Experiments results show the proposed model is robust to noise, independent of initialization and unambiguous segmentation. Compared with the traditional variational models, the proposed model can get more accurate results and higher computational efficiency. © 2016


Wang L.,East China Institute of Technology | Wang L.,Key Laboratory of Watershed Ecology and Geographical Environment Monitoring | Wu F.,East China Institute of Technology | Wu F.,China University of Mining and Technology | Wu L.,East China Institute of Technology
Wuhan Daxue Xuebao (Xinxi Kexue Ban)/Geomatics and Information Science of Wuhan University | Year: 2016

In the current research on the total least squares method in the conversion of GPS height, the calculation of the conversion parameter and elevation abnormities of the check points are generally performed in two steps, and only consider the error in the coefficient matrix used to calculate the parameters; errors in the coordinate of the check point are ignored. In view of this gap, we put forward a total least squares fitting estimation model of GPS height transformation, that combines the calculation of fitting parameters with the calculation of elevation abnormities at inspection points, and considers the position error of all points. Collocation calculation experiemental results verify the feasibility of this method. These test results show that the method can effectively improve the accuracy of elevation conversion. © 2016, Research and Development Office of Wuhan University. All right reserved.


Wang L.,East China Institute of Technology | Wang L.,Jiangxi Province Key Laboratory for Digital Land | Wang L.,Key Laboratory of Watershed Ecology and Geographical Environment Monitoring | Yu D.,East China Institute of Technology | Lu K.,East China Institute of Technology
Cehui Xuebao/Acta Geodaetica et Cartographica Sinica | Year: 2015

On the basis of complex least squares adjustment method (CLSAM), the theory of complex total least squares adjustment method (CTLSAM) is proposed. The algorithms of complex total least squares and complex LS-TLS method are derived. Through two examples, the complex LS method under the adjustment criterions that minimize the sum of squares of the module of observation vector residual (adjustment criterion 1) and the sum of squares of the real part and imaginary part of the observation vector (adjustment criterion 2), the complex TLS method under the adjustment criterions that minimize the sum of squares of the module of observation vector and coefficient matrix residual (adjustment criterion 3) and the sum of squares of the real part and imaginary part of the observation vector and coefficient matrix residual (adjustment criterion 4) are compared and analyzed respectively. The results of two examples show that the CLSAM under the adjustment criterion 1 is more reasonable than the adjustment criterion 2; the CTLSAM under the adjustment criterion 3 is more accurate than the adjustment criterion 4; the CTLSAM under the adjustment criterion 3 is better than the CLSAM under the adjustment criterion 1 when the coefficient matrix contains stochastic noise. ©, 2015, SinoMaps Press. All right reserved.


Wang L.,East China Institute of Technology | Wang L.,Key Laboratory of Watershed Ecology and Geographical Environment Monitoring | Xu G.,East China Institute of Technology | Xu G.,Wuhan University
Wuhan Daxue Xuebao (Xinxi Kexue Ban)/Geomatics and Information Science of Wuhan University | Year: 2016

Considering the situation that the weight matrix of observation vector and coefficient matrix may be inaccurate, an available algorithm is introduced in this paper, which is derived on the basis of combining the Helmert variance component estimation with a kind of fast weighted total least squares algorithm in the errors-in-variables models. And the derivative process of the fast weighted total least squares is described in detail and the comparison with three other algorithms is implemented in this paper. Using the fast weighted total least squares algorithm combining Helmert variance component estimation derived in this paper, the stochastic model and the unknown parameters of the functional model can be solved simultaneously. Three empirical examples, two straight line fitting and one linear parameter estimation, are also used to investigate the application of posteriori estimation of stochastic model on weighted total least squares problem. Results show that the algorithm is very effective. © 2016, Wuhan University. All right reserved.


Li H.,Wuhan University | Li H.,Key Laboratory of Watershed Ecology and Geographical Environment Monitoring | Zhong C.,Chongqing Three Gorges University
Sensor Review | Year: 2016

Purpose - This study aims to find a feasible precise navigation model for the planed Lunar rover. Autonomous navigation is one of the most important missions in the Chinese Lunar exploration project. Machine vision is expected to be a promising option for this mission because of the dramatic development of an image processing technique. However, existing attempts are often subject to low accuracy and errors accumulation. Design/methodology/approach - In this paper, a novel autonomous navigation model was developed, based on the rigid geometric and photogrammetric theory, including stereo perception, relative positioning and absolute adjustment. The first step was planned to detect accurate three-dimensional (3D) surroundings around the rover by matching stereo-paired images; the second was used to decide the local location and orientation changes of the rover by matching adjacent images; and the third was adopted to find the rover's location in the whole scene by matching ground image with satellite image. Among them, the SURF algorithm that had been commonly believed as the best algorithm for matching images was adopted to find matched images. Findings - Experiments indicated that the accurate 3D scene, relative positioning and absolute adjustment were easily generated and illustrated with the matching results. More importantly, the proposed algorithm is able to match images with great differences in illumination, scale and observation angle. All experiments and findings in this study proved that the proposed method could be an alternative navigation model for the planed Lunar rover. Originality/value - With the matching results, an accurate 3D scene, relative positioning and absolute adjustment of rover can be easily generated. The whole test proves that the proposed method could be a feasible navigation model for the planed Lunar rover. © Emerald Group Publishing Limited.


Liu Y.,Wuhan University | Zhang L.,Wuhan University | Wei X.,Key Laboratory of Watershed Ecology and Geographical Environment Monitoring | Wei X.,East China University of Technology | Xie P.,Wuhan University
Ecological Indicators | Year: 2016

The assessment of the value of ecosystem services is a valuable tool for biodiversity conservation that can facilitate better environmental policy decision-making and land management, and can help land managers develop interventions to compensate for biodiversity loss at the patch level. Previous studies have suggested that it is appropriate to assess the value of biodiversity for conservation planning by considering both the condition of the landscape and the spatial configuration of adjacent land uses that can be reflected as a proximity effect. This research examines the influence of spatial proximity on biodiversity conservation from the ecosystem service perspective based on the assumption that the variation in the proximity effect caused by land cover change has positive or negative impacts on ecological services. Three factors related to the spatial characteristics of the landscape were considered in this approach: the relative artificiality of the land cover types, the distance decay effect of patches and the impact of one land cover type on others. The proximity effect change (PEC) parameter reflected the relationship between the spatial proximity effect and biodiversity conservation. The results of a quantitative and spatial comparative analysis of the proposed method and the conventional method in Yingkou for the periods of 2000-2005 and 2005-2010 showed that the former can account for the temporal and spatial changes in ecosystem services for biodiversity conservation that were caused by patch-level changes as well as the interaction between the altered and adjacent patches from a spatial perspective. The metric can also identify the most critical areas for biodiversity protection and inform the efficient allocation of limited land resources for nature conservation to maximize the benefit to biodiversity by guiding the process of land-use change, particularly urbanization and agriculture. Future studies should focus on the other important factors that are applicable to the assessment of the value of biodiversity conservation in socio-ecological systems, where society and nature are mutually capable of fulfilling their roles. © 2016 Elsevier Ltd. All rights reserved.


Liu Y.,Wuhan University | Wei X.,East China University of Technology | Wei X.,Key Laboratory of Watershed Ecology and Geographical Environment Monitoring | Li P.,Wuhan University | Li Q.,Wuhan University
Ecological Indicators | Year: 2016

Sensitivity of landscape metrics to selection of spatial scale (i.e., resolution or areal extent), land-use categories, and different landscapes has led to unreliable conclusions for practitioners of landscape analysis and modeling. Unlike previous studies that mostly considered such metrics and assessed the effect of each factor separately, our study focuses on the sensitivity of the correlation structure of different sets of landscape metrics as a whole under different situations via principal component analysis (PCA). We used the congruence coefficient (rc) to calculate the changes in factor structures under different situations. We used 16 class-level and 15 landscape-level metrics of 900 village-based and 150 town-based samples that were collected from three regions. Five cell sizes, two land-use classes, and two sets of land-use metrics were also considered. We did not control the cell sizes, sample extent, and different landscapes in the sensitivity analysis to study the interactive relationships between different factors. All factors strongly influence the correlation structure of the landscape metrics, with each factor demonstrating a unique influence. Changing cell size significantly affects the correlation structures in the plain region, especially in croplands and built-up lands. Town-based results show a relatively more stable correlation structure than village-based results (except in land-use categories). Different land-use classes show different responses to changing cell size, sample extent, and sets of landscape metrics in different regions. These results show the great interactive influences of these factors, which have often been overlooked in previous studies. The conclusions drawn from fixed factors may be conditional and inapplicable to other situations. The sensitivity of the correlation structure in diverse regions may improve our understanding of landscape metrics as a whole and can provide further insights into the correlation structure of landscape metrics for land-use management and monitoring. © 2015 Elsevier Ltd. All rights reserved.


Ming L.,Wuhan University | Ming L.,Key Laboratory of Watershed Ecology and Geographical Environment Monitoring | Ming L.,Jiangxi Provincial Geomatics Center | Fang P.Y.,Key Laboratory of Watershed Ecology and Geographical Environment Monitoring | Fang P.Y.,Jiangxi Provincial Geographical National Conditions Monitoring and Remote Sensing Institute
Cybernetics and Information Technologies | Year: 2015

Considering the prevention and management of the major emergencies in China and the increasingly severe environmental security situations, a visualization emergency solution, based on a mobile mapping system is proposed. This paper studies the key technologies of a mobile mapping system in emergency management. It considers the design of a total factor and full-texture real map, which is measurable and can be marked through the mobile mapping technology. It also proposes the application of a real map in emergency cases, which has large practical significance.


Chen Z.,East China University of Technology | Chen Z.,Key Laboratory of Watershed Ecology and Geographical Environment Monitoring | Wang S.,East China University of Technology | Wang S.,Key Laboratory of Watershed Ecology and Geographical Environment Monitoring | Wang Z.,Yangtze Estuary Hydrology and Water Resources Survey Bureau
Flow Measurement and Instrumentation | Year: 2016

Spatiotemporal fitting by the least squares method is commonly applied to separate the mean flow (runoff) and tidal current from vessel-mounted ADCP data in tidal reach. To analyze this technique in an estuary region with interaction of the runoff and tide, three sets of 29-h periods vessel-mounted ADCP data in Yangtze Estuary is tested. A diverse set of basis functions is studied and a nodes determination method, named gradient algorithm, is proposed for comparison purposes. The Green function together with a nodal configuration determined by gradient algorithm is the best option. In general, the semi-major axis of the principal tidal ellipse (M2) is parallel to the riverbank and the phase of shoal waters is ahead of that of thalweg, in keeping with shallow-water tide wave dynamics. Because the tidal currents in Yangtze Estuary are explained by shallow-water tide wave dynamics, the use of the Green function and gradient algorithm in the spatiotemporal fitting by least squares technique is a promising scheme for detiding vessel-mounted ADCP data in shallow-water tide wave dynamics systems. © 2016 Elsevier Ltd


Lu T.,East China University of Technology | Lu T.,Chang'an University | Lu T.,Key Laboratory of Watershed Ecology and Geographical Environment Monitoring
Cehui Xuebao/Acta Geodaetica et Cartographica Sinica | Year: 2016

Computational problem of gross errors estimation is discussed based on the mean shift model, and the gross errors estimation formulas of the observed statistical correlation data snooping method are given. The relationships of gross errors estimation of the data snooping method, the method of simultaneous locating and evaluating multidimensional gross errors (LEGE), quasi-accurate detection of gross errors (QUAD) method and the partial least-squares (PLS) method are discussed. It is proved that ①in the case of correlated observations, calculation of gross errors estimation of the PLS method and the QUAD method are equivalent. However, these two methods are different with the data snooping method and the LEGE method; ②in the case of uncorrelated and unequal weight observations, calculation of gross errors estimation of the QUAD method, the PLS method and the data snooping method are equivalent, but these three methods are different with the LEGE method; ③in the case of uncorrelated and equal weight observations, calculation of gross errors estimated value of these four methods are equivalent. Finally, the case studies verify the conclusions. © 2016, Surveying and Mapping Press. All right reserved.

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