Table of Content

25 February 2012, Volume 41 Issue 1

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学术论文

Slepian Localized Spectral Analysis of the Determination of the Earth’s Gravity Field Using Satellite Gravity Gradiometry Data

2012, 41(1):  1-0. 

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The polar gaps in satellite geodesy lead to poor estimability of low order spherical harmonic coefficients of the Earth’s gravity field model. The Slepian localized spectral analysis method is introduced in this paper and its mathematical characteristics are analyzed. Grünbaum operator is introduced into the solution process in order to improve the computational efficiency and stability. Then, the practical formulas of Slepian method for recovering the gravity field with satellite gravity gradiometry data are educed and numerical analysis are done. The results indicate that, Slepian function is orthogonal in both the sphere and the belt, and its spectral energy distribution characteristic is in accord with the orbit characteristic. Also, the accuracy of Slepian method in Slepian domain is better than that of Legendre solution in spherical harmonic domain. However, the contribution of Slepian method to the improvement of geoid is limited.

A Study on Adjustment Theory and Methods with Criterion Containing Parameters

2012, 41(1):  8-0. 

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Abstract: The adjustment models with criterion containing parameters include the semi-parametric model, the regularization model and the Vondrak filtering model, etc, which can be considered as supplements and extends of the Least Squares (LS) model. The key problem of these models is how to choose the parameters in the criterion. Many methods have been suggested by now, but united theory still not be formed. In this paper, a new method with virtual observations is proposed to solve all the models here, which can be used to choose the proper parameters of all the models and get the solutions of them. To compare with the LS model and other models, an example is presented to illustrate the feasibility and advantages of this method.

Comparative Analysis of Statistical Tests Used for Detection and Identification of Outliers

2012, 41(1):  14-0. 

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The least-squares (LS) adjustment approach is very susceptive to outliers. A comparative analysis of statistical tests used for detection and identification of outliers, including Gaussian normal test, Tau test and Student’s t-test, were addressed in details. Both the standardized local sensitivity indicator and the standardized LS residual can be served as Gaussian normal test statistics for outlier detection. However, the former is superior to the latter one for correlated observations in the sense of detection power. When the variance factor is not known, the internally Studentized residual and externally Studentized residual can be employed to perform Tau test and Student’s t-test, respectively. In a parallel manner, the internally Studentized local sensitivity indicator and externally Studentized local sensitivity indicator were constructed and investigated. Since the probability of not rejecting the null hypothesis when it is false (type Ⅱ error) may be too high by using Student’s t-test, and since the Tau test has a limitation in itself, both of them are not appropriate statistical tests. To circumvent this difficulty, the standard deviation involved in the standardized local sensitivity indicator can be replaced by its normalized robust least median of squares estimator, and then perform the Gaussian normal test for detection and identification of outlying observations.

A Two-step Method to Determine Relative Weight Ratio Factors in Joint Inversion

2012, 41(1):  19-0. 

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The two-step method to determine relative weight ratio factors in joint inversion is derived in this paper. In the first step, without considering relative weight ratio factors, the joint inversion model of two or more kinds of observation data is established. Through Helmert method of variance components estimation, unit weight variances of observation data are equal (or the ratio of unit weight variances is approximate to 1), and the reasonable and theoretical weight matrix is determined. At the sametime, different kinds of observation data are normalized. In the second step, on the base of reasonable weight matrix, the joint inversion model considering relative weight ratio factors is established. The relative weight ratio factors are determined when objective function is minimum. Through simulated data and several solutions, the effectiveness and feasibility of two-step method are proved.

The Approach of GPS Height Transformation Based on EGM2008 and SRTM/DTM2006.0 Residual Terrain Model

2012, 41(1):  25-0. 

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The resolution and accuracy of EGM2008 is higher than any other models released in the past ten years, this corresponds to a spatial resolution of 5 arc minutes, so it is clear that high-resolution terrain model is necessary for computing high-frequency components of height anomaly and achieving higher accuracy GPS height transformation. Based on residual terrain model theory, the approach of RTM data construction and RTM height anomaly computation are discussed using SRTM and DTM2006.0 global digital terrain model. Several GPS/leveling points are selected with optimal choice method for constructing the residual height anomaly interpolated model according to their measured height anomaly, EGM2008 height anomaly and RTM height anomaly, and then the accuracy of height anomaly can be improved. Finally two cases of GPS/leveling data are adopted in this paper, and the results show that the accuracy of GPS height transformation can be obviously improved using model height anomaly computed from EGM2008 model expanded to 2160 degree and order and SRTM/DTM2006.0 residual terrain model.

Algorithm for Network RTK (VRS) based on star structure

2012, 41(1):  33-0. 

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In view of the deficiency of the triangular network in present Network RTK (VRS), the paper firstly establishes a kind of baseline solution method of network RTK (VRS) based on star structure, and proposes the ambiguity resolution method applicable to star structure. Then further research is done to analyze the algorithm of ionospheric and tropospheric correction separately. Lastly, verify and analyze the network ambiguity resolution and correction calculation in both star structure network and traditional triangular network through two tests. These tests indicate that the Network RTK (VRS) based on star structure this paper proposes can obviously accelerate the fixed time of network ambiguity resolution, which can be up to 50%, and can achieve higher precision and reliability in the generation of network correction. The results of research can have important theoretical meaning in the wider use of Network RTK (VRS).

The timing equation of pulsar navigation in 1PN approximation and accuracy analysis

2012, 41(1):  41-0. 

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the time of arrival equation of pulse and timing equation of pulsar navigation in 1PN approximation is derived. The general relativity effect of the timing equation is analyzed; the binomial expand expression of timing equation is given, based on which the timing error due to the pulsar ephemeris is discussed. In the end, the effects of planet ephemeris error and the flattening of bodies are presented.

The consistence between row-wised weighted total lest squares and condition adjustment with parameters

2012, 41(1):  48-0. 

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Traditional Least-square adjustment in surveying and mapping fields is based on indirect adjustment model, which are under the facts of a single observation such as angle and distance could be expressed as the explicit function of parameters. In modern surveying technology, coordinates, baselines and point clouds are original observations, the function of the parameters and the observations are usually given in an implicit way, and the function should be linearized as the condition adjustment with parameters. But in most applications, the adjustment are not conducted in this way, the total least squares and the residual error least-squares are often performed to resolve such problems. The consistence between the weighted total least squares and the condition adjustment with parameters are verified in this paper to promote the applications on modern surveying data processing with TLS and its extended models.

Local Analysis Method on Gross Error of Multidimensional Adjustment Problem

2012, 41(1):  54-0. 

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As demonstrated by an example of leveling network, existing methods of correcting gross errors based on residuals have a few shortcomings including the dependence on the location of gross errors within the leveling network. To address these problems, Local Analysis Method (LAM) is proposed. In multidimensional adjustment problem, an observed quantity usually can be expressed as function of other observed quantities. Then we can obtain a group of independent observed values of the observed quantity, which includes observed value corresponding to the observed quantity and functions of other observed values. And an approach to search functions based on the design matrix is given. So the analysis conclusion of one-dimensional problem can be used to test if the observed quantity can tolerate gross error. A method based on Combined Observed Value (function of other observed values) is also developed to detect gross errors using true errors. Finally, this detection method and LAM are detailed in an example of a goniometric network.

An Algorithm of SAR Image Denoising in Nonsubsampled Contourlet Transform(NSCT)Domain Based on Maximum A Posteriori(MAP) and Non-Local(NL) Restriction

2012, 41(1):  59-0. 

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An algorithm of SAR image denoising in Nonsubsampled Contourlet Transform(NSCT) domain based on Maximum A Posteriori(MAP) and Non-Local(NL) restriction is proposed in this paper. Nonlogarithmic additive model is applied to SAR image, and then the statistical distribution of the noise within nonlogarithmic additive model is modeled in the NSCT domain. MAP and NL restriction are used to get the NSCT coefficients of the real signal. Experiments show that the algorithm proposed in this paper is effective in SAR image denoising, and also possess high performance over many traditional algorithms.

An High-quality Image Objects Generating Method based on Multi-resolution Topology Network

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2012, 41(1):  65-0. 

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In this paper, a topology heuristic segmentation algorithm is proposed based on multi-resolution topology network and some key technologies are discussed in detail. The results of segmentation experiments show that it is feasible to generate high-quality image objects with this proposed algorithm.

A New Method for Fine Registration of SAR Images in PS InSAR

2012, 41(1):  69-0. 

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A new method for fine registration of a low-coherent SAR images pair in PS InSAR is presented and implemented. This method completes original registration of the low-coherent SAR images pair with the help of the third image that has higher coherence with the master and slave image, and then calculate the coordination mapping function between them using weighted least square method to achieve quickly and efficiently high precise sub-pixel level registration of the low-coherent SAR images pair. A registration experiment with ERS-1/2 SAR images is carried out and the results show that the method can improve the interferogram quality, coherence, registration accuracy of control points and registration effect between the low-coherent SAR images pair. So the new registration method can to some extent solve the registration problem of the low-coherent SAR images pair..

Interactive Segmentation Technique and Decision-Level Fusion Based Change Detection for SAR Images

2012, 41(1):  74-0. 

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To avoid needing a preprocessing for reducing the speckle noise, and meanwhile overcome the limitation of selecting the distribution model, we integrate the characteristics of the DI with an interactive segmentation method not referring to any distribution assumption to generate the change detection maps corresponding to the different “seeds”, and then use a voting competition strategy to fuse those results to generate the final change detection map. During the segmenting, the feature of each pixel is set as a vector consisted of the corresponding intensities in the DI and each scale representation of the DI given by the use of stationary wavelet transform (SWT). This kind of features and the decision level fusion make our proposed method a certain robust to the speckle noise. The results tested on real SAR datasets and obtained under the situation that there is no despeckling preprocessing to SAR images, those performances are better than that of other techniques.

The Effect of SAR Wavelength on Remote Sensing Image Statistical Features

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2012, 41(1):  87-0. 

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The statistical feature of the remote sensing image plays an important role for image recognition, image registration and image classification. The traditional robustness analysis of statistical feature is generally based on that the remote sensing images have same sensor parameters. However, this is not true in many practical applications, where the sensors may have different sensor parameters, e.g., wavelength and incidence angle etc. Due to various types of sensor parameters, the remote sensing image will have different appearance. This will further affect the statistical features. Therefore, in order to achieve more robust image processing and analysis, it's necessary to investigate the correlations between the statistical features used in the state of the art and the sensor parameters. In this paper, we research on the robustness of six kinds of statistical features against the wavelength (L-band, C band and X band) of the synthetic aperture radar (SAR). First the measurement of robustness of statistical features is defined, and then the comparison and analysis are presented in our experiment. In addition, our experiment also shows that statistical features of different terrains have different change while wavelength changes. The results of this paper also play a very important role in the SAR image based interpretation, image matching guidance and scene adaptability analysis.

A Phase Unwrapping Algorithm Based on Multi-baseline Combined Frequency Estimate

2012, 41(1):  93-0. 

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A new phase estimate algorithm for multi-baseline interferometry is proposed in this paper. This method consists of two steps: firstly, selects the appropriate set of baselines and unwraps the interferogram associated with the shortest baseline; then gains the unwrapped phase of the longest baseline by using the maximum likelihood estimator to extract the frequency of any complex pixel. The method proposed in this paper is simple and effective, and error propagation effect of this technique is very small. The method does not require plenty of iterative operation, even the step of phase unwrapping will be omitted when the shortest baseline is short enough. Simulation data processing results validate the effectiveness of proposed method.

Multiscale Edge Detection in Multispectral Remotely Sensed Imagery Based on Vector Field Model

2012, 41(1):  100-0. 

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A novel algorithm to detect the multi-scale edge features on multispectral remotely sensed imagery which is based on the concept of combining vector field model with dyadic wavelet transform was proposed, and two different neighborhood models in the algorithm was introduced to lead to locate edge points more complete. Firstly, multispectral images are defined by using of the vector field model. And then the dyadic wavelet transform is applied to produce the multi-scale edge detail coefficients, and first fundamental form is used for detecting the gradient magnitude and orientation of multispectral images at different levels. Lastly, edge points are located along with the quantified orientation of gradient by using the optimal neighborhood model at different scales. This representation can provide a local measure for the contrast of a high-resolution multispectral image at different scales. A variety of experiments by using QuickBird multispectral images of Nanjing area were presented to demonstrate the representation efficient. It is shown from the results that the edge information of the objects, i.e. factory, paddy, can be detected clearly from coarse to fine at different scale levels. This paper analyzed the relationship of the size of the ground features between the spatial resolution of image and to try to find a suitable level to demonstrate the feature of different objects. And the local maximum of the gradient magnitude provides information of the image edge feature which can be detected from the gradient modulus along with the quantified gradient orientation. And this paper figured out that quantification of the gradient orientation should consider the direction of objects in the image. Using F-measure, the results by the proposed method has higher precision than the traditional edge detectors.

Formal Classification of Spatial Incremental changes

2012, 41(1):  108-0. 

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The classification and description of spatial incremental changes is one of the fundamental problems in geo-spatial data modeling and updating. It has a significant role in the spatio-temporal data organization, incremental change capture, event-based updating and propagation of changes. Existing studies in this field was focused mainly on the classification of the whole of objects and the incremental changes of spatial objects has not been well addressed. This paper examined the role of the common parts of two spatio-temporal objects and proposed to consider both the common parts and differences in the distinguishing and formalizing the incremental changes of spatial objects. A formal description model was proposed based on three elements, i.e., difference, difference by, and intersection, with the associated regularization operation. A formal classification of the incremental changes was derived for both area and linear objects. The results of this formal classification have been applied to develop the operations of incremental capture and to visualize and analyze the incremental changes.

Annotation of Geographical Named Entities in Chinese Text

2012, 41(1):  115-0. 

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Semantic interpretation of geographic information in natural language text can help people more in-depth understand the mechanism of geospatial cognition and spatial language, and enhance the intelligence of spatial query in geographic information systems (GIS), spatial reasoning, and geographical information retrieval etc. Corpus annotation is the task of analyzing specific language information, linguistic structure of domain information found in the text, and the establishment of the metadata describing them. Firstly, this paper analyzes the difference of representation of geographical entities in Chinese text and GIS. Secondly, based on the description of linguistic characteristics of geographical named entities in Chinese text, an annotation scheme is presented and the annotation specification is given in detail. Finally, GATE（General Architecture for Text Engineering）is introduced as a annotation platform, and a large-scale annotated corpus （i.e. GeoCorpus） based on "Encyclopedia of China Geography" (2,130,000 bytes of Chinese text) is established and evaluated. This study effectively addresses the current lack of related standardization and standardized data. The further work will focus on the following work: 1) Establishing a general corpus annotation based on web pages to resolve the imbalance of GeoCorpus; 2) Developing a visual annotation tool integrating GIS database with GATE to further improve annotation performance; 3) Annotation of spatial relations in Chinese text based on the theory of spatial semantic rules.

Grid Pattern Recognition in Road Networks Based on C4.5 Algorithm

2012, 41(1):  121-0. 

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The pattern recognition of spatial cluster has become a hot issue in the areas of geographical information sciences. Pattern recognition of road networks plays an important role in map generalization, data matching and spatial analysis. Grid pattern is one of the most typical patterns in road networks. A grid is characterized by a set of mostly parallel lines, which are crossed by a second set of parallel lines with roughly right angle. This paper proposes a method for grid pattern recognition based on C4.5 algorithm. Meshes in road networks can be classified as belonging to grid and not belonging to grid according to their context. Firstly, shape measures and relation measures are defined to characterize meshes in road networks. Secondly, two classifiers are trained using C4.5 algorithm based on five measures data and three measures data. A 10-fold cross validation process is applied in order to obtain a sounder result. Finally, the performance of the classifiers is evaluated by means of the Kappa index and the overall correct rate. The Kappa classification accuracy for five dimensions data and three dimensions data is 0.63 and 0.66. The overall correct rate is 81.7% and 82.9% for each. The confidence interval of 90% confidence is [0.785, 0.846] and [0.797, 0.857] respectively. The classifiers are tested by a new data set and the results show that the classifiers are valid in grid pattern recognition. This study tries to use theories and methods of traditional pattern recognition and data mining to solve the spatial issues.

Calculating Model for the Topology Stable Area of the Plane Discrete Points

2012, 41(1):  127-0. 

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The paper aims to present a method to maintain the neighboring relations before a point is moved without reconstructing the delaunay triangulation or the Voronoi diagram. A new concept of the Topology Stable Area is put forward firstly, then the two conditions which the point in the topology stable area should be met are proved by the empty circle rule of the delaunay triangulation, one is that the neighboring relations between the moving point and it’s first order neighboring point must be maintained, another is that there is no new first order neighboring point of the moving point is created. A novel calculation method of the topology stable area of the plane discrete points based on the Voronoi diagram and delaunay triangulation is presented. And it’s correctness is proved by the experiment.

Study on Map-matching Algorithm for Floating Car

2012, 41(1):  133-0. 

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For the key technical problems the existing map-matching algorithms for floating car face when used in urban complex road network, in this paper, based on the floating car data, an urban transportation network is created with SuperMap GIS platform, and a new map-matching algorithm for floating car is studied. The algorithm includes candidate road determination based on grid, GPS point matching based on distance, heading and reachability weights and driving track selection based on shortest path. The algorithm is capable of meeting the requirements of accuracy and real-time performance of floating car map-matching, and has the potential to provide a reliable basis to obtain the traffic congestion information of urban transport.

Modeling and metrics of higher order fuzzy geographical phenomena

2012, 41(1):  139-0. 

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Modeling and metrics of fuzzy geographical phenomena have gained some products. But existing models can’t measure the error of membership value, so those models can’t satisfy to objectively describe complex natural and artificial phenomena. The scale effect and measurement error are two major objective reasons which bring forth the membership error of vague geographical phenomena while subjectivity of relative workers and difference of standards between departments are major subjective reasons. A fuzzy geographical object model is proposed based on interval type-2 fuzzy sets, and the metrics of length of interval type-2 fuzzy line and area of interval type-2 fuzzy region are developed too, then the membership error of interval type-2 fuzzy geographical object is analyzed. This model can handle uncertainty of membership value and avoid some limitations of existing models. The model and relative metrics methods have broad applications in natural hazard analysis, global change , land cover change and so on.

Automatic Construction of Topological Relationship of 3D Geological Blocks Based on Stratified Geological Structure

2012, 41(1):  147-0. 

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The acquisition of the geological block structure model which is based on stratified geological structure is one of the most important steps in geological modeling. In present construction methods, attention is merely paid to the extraction of geological blocks and the improvement of the algorithmic efficiency, but not the establishment of the topological relationship between geological blocks and their faces or the establishment of the topological relationship between geological blocks. In this paper, a new construction method is proposed, and its basic idea is: firstly, direction-edge and direction-triangle are extracted by making use of the relationship between the boundary lines and the faces; and then the sort-table of three-dimensional faces is established according to right-hand rule; finally, the positive and negative body of each face is obtained according to certain ergodic rules. This method can not only be used to automatically define the relationship between the geological blocks and their faces, but also indirectly analyze the adjacent relationship between geological blocks, so as to lay the foundation for the establishment of the three-dimensional geological structure model as well as the query and analysis of the three-dimensional topological block.

The matching and consistency Correlation in the integration of contour and river data

2012, 41(1):  152-0. 

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As the representation of terrain surface and height information, the contour data has the strict constraint relationship with the distribution of river network. In spatial data integration and matching, the inconsistency usually occurs between the river and contour generating “river climbing slope”. This study presents a method to build thee matching relationship and to correct the inconsistency between river and contour data. Based on Delaunay triangulation, the terrain landform features is extracted and by bend analysis build the matching relations between river and contour. According to different inconsistency situations, we offer two correction approaches depending on which data is precise, which includes the river displacement referenced to the contour and the opposite.