Table of Content

22 April 2010, Volume 39 Issue 2

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学术论文

Maximum Likelihood Estimation in Mixed Integer Linear Model with P-Norm Distribution

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2010, 39(2):  0-145. 

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The integer parameters must be primarily estimated in the GNSS and INSAR application, which essentially introduces a special mixed integer model with both real- and integer-valued parameters from mathematical point of view. Up to now, all methods for mixed integer model are based on the least squares criterion. In this paper, the parameter estimation will be investigated in mixed integer model with the P-norm distributed observation noises. First of all, we will employ the maximum likelihood estimation theory to derive the criterion for integer searching, considering the fact that only real parameters can be differentiated but not the integer parameters due to their discrete property, and further verify that least squares based integer searching criterion is just a case with normally distributed noises. Secondly, the approach and iterative procedure are given for estimating p, searching integers and solving real-valued parameters. Finally, the simulated experiments are implemented to verify the correctness of the derived formulae and proposed algorithm.

Symbolic Expressions of the Track Calculation Methods Based on the Ellipsoidal Model

2010, 39(2):  0-145. 

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The deficiencies of the traditional track calculation methods are analyzed in this paper. In order to improve the accuracy of track calculation, the symbolic formulae of meridian arc’s forward and inverse solution are introduced, then the modified Mercator sailing method is derived based on the ellipsoidal model. The calculation formula of middle latitude is derived from its geometrical definition based on an elliptical earth, and the modified middle latitude sailing method is also available. The two methods derived by this paper are both symbolic expressions, so they could solve the problem of accurate track calculation when different referenced ellipsoids are used, and thereby provide a theoretical model for the development of accurate automatic navigation.

The Construction of Newly Stable Celestial Reference System

QIAO ShuboQIAO ShuboLI Jin-Ling ²,LI Jin-Ling ², ³,³, ³,³, ³, ³

2010, 39(2):  0-145. 

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When we descript the motion of spherical bodies and some geophysical phenomena, we need one high precision and steady celestial reference system(CRS). Ideal celestial reference system equate to an inertia reference system, we call them basic celestial reference system. Celestial reference frame(CRF) is the realization of ideal CRS, which stability directly determined the precision of motion of objects and some geophysical phenomena. Based on nearly 30 years astrometric/geodetic observed data of global IVS（International VLBI Service）net between 1979 to 2007, we calculated and analyzed the data using CALC_Solve software system on Shanghai Astronomical Observatory, Chinese Academy of Sciences. Then we acquired a series coordinates(right ascension and declination) of radio sources, which can be made up to time series for our research. Stability of sources are checked and analyzed by the time series, we worked out a set of standard of selection on stable sources, and then we acquired a set of table of stable sources. At last we realized a newly stable celestial reference system consist of 173 stable defining sources and 135 supplement sources, which padded the blank of not renewing ICRF(International Celestial Reference Frame) for more than 10 years. The newly CRF can provide highly precision reference frame for some problems correlation on geodesy, astrometry and geophysics research.

A Map Matching Algorithm for GPS Tracking Data

2010, 39(2):  0-145. 

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Map matching GPS floating car tracking data is different from that for traditional navigation system according to the specific application. With the consideration that GPS floating car tracking data provide a global moving trend, using drive constraints in city road networks, this paper proposed a novel map matching method based on road connectivity under geometric topology and traffic control constraints as well as the similarity between the curve of trajectory and the outline of road paths. This algorithm can get good map matching results and was validated through experiments, and finally could support the further analysis and application of GPS floating car data.

Evaluating on precision index of Vehicle-borne urban information acquisition and 3D modeling system

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2010, 39(2):  0-145. 

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The error sources and rigorous deducing of Vehicle-borne urban information acquisition and 3D modeling system (3DSurs) is analyzed on theory in this paper, and we analyze and evaluate the theorical precision, and get the precision index of 3Dsurs system. The error of 3Dsurs system includes error from GPS receiver antenna positioning, vehicle-borne attitude measurement, coordinate transformation, and scanner calibration and so on, it is shows that the plane precision is up to 10cm and the height precision is about 20cm of from theory analysis and large numbers of experiments.

Creating Class Intervals for Choroplethic Maps Based on Multiobjective Genetic Algorithm

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2010, 39(2):  0-145. 

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Creating class intervals for choroplethic maps is a common and traditional subject in cartography, which is widely applied in many fields. The core of the problem is how to specify the class intervals. However, this work has focused almost exclusively on grouping the nearby distributed data into several ordinal bins along the number line. All enumerated units that fall into each bin are then assigned an areal symbol that is used to create the choroplethic map. The geographical characteristics of the data are only indirectly considered by such approaches in classification. In this article, we design, implement, and evaluate a new approach in classification that places class-interval selection into a multi-criterion framework. In this framework, we consider not only number–line relationships, but also the area covered by each class, the fragmentation of the resulting classifications, and the degree to which they are spatially autocorrelated. This task is accomplished through the use of a genetic algorithm (SIM-MOGA) that creates optimal classifications with respect to multiple criteria. Finally, the method has been tested in the urban land grading of Huibei Province.

Unsupervised Two-Threshold Change Detection Algorithm Based on Wavelet Transform in Multi-temporal SAR Images

2010, 39(2):  0-145. 

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The difficulty of multi-temporal synthetic aperture radar (SAR) image change detection is that SAR coherence imaging mechanism is very complex and it brings speckle noise. Wavelet multi-scale decomposition can reach the balance effect for the reduction of SAR image speckle noise and the protection of geometry detail, furthermore, it can describe SAR image changes through different scales. This paper proposes the unsupervised two-threshold wavelet transform (UTWT) SAR image change detection algorithm. Using the expectation maximization (EM) algorithm produces two threshold values, which can distinguish change classes (the enhanced change region and the weakened change region) or change grades. Finally, some SAR images perform experiments and the experimental results verify that the method is effective.

Global sea level variations from combined Jason-1 and GRACE data

2010, 39(2):  0-145. 

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Sea level variations are mostly caused by ocean mass variations and steric sea level variations. Seasonal variability of global mean sea level and its two components from September 2002 to April 2008 is investigated respectively from combined GRACE time variable gravity and Jason-1 satellite altimeter data. Mean sea level change from combined satellite observations is quite consistent with WOA05 results at annual amplitudes and phases. The secular trend of global mean sea level change and its two components is estimated, during over 6.5 year`s time scale, global mean sea level rises at a rate of +2.0±0.4 mm/a, the respective contribution of ocean mass sea level and steric sea level is estimated to be +1.4±0.4 mm/a and +0.5±0.3 mm/a.

study on Block Adjustment for Long-Strip satellite CCD Images

2010, 39(2):  0-145. 

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The orientation model of space borne images based on orbit parameters and that based on state vectors are compared in this paper. A method for the fitting of orbit and the interpolation of state vectors based on imprecise ephemeris data is proposed and the orbit correction model that is suitable for long-strip satellite image orientation is built in flight coordinate system. Then, the influence of rotation of the Earth to the rigorous orientation model of satellite linear array images is analyzed. Through adaptive process of the yaw angle, imaging equation and block adjustment model of spaceborne linear array images are built based on satellite state vectors in Earth Centered Rotating coordinate system. At last, 4 pairs (8 scenes) SPOT5/HRS long-strip stereo images in Eastern Tibet Plateau and Eastern Talimu Basin from Project of China Western Topographic Mapping at 1:50,000 scale are used as data sources. According to different numbers and distributions of GCPs, positioning experiments of different schemes are carried out. Experiment results show that the statistical precision can achieve 8.0 m under the circumstance of sparse GCPs.

测绘快报

On Three-dimensional Visualization of Geospatial Information: Graphics based or Imagery based?

2010, 39(2):  0-145. 

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3D visualization of geospatial information has constituted one of the basic requirements of geo-information service nowadays, along with popularity, openness and capabilities of target-measuring and knowledge-mining. Currently, there are two major technical routines for 3D visualization of geospatial information, that is, the graphics based and the imagery based approaches. This paper elaborates the basic principles, technical connotation and manifestations of these two types of approaches, with some typical application instances illustrated correspondingly; by comparing the two kinds of visualization methods in terms of their advantages and disadvantages as well as the application scopes, it is concluded that there is a developing tendency to combine the graphics based and imagery based techniques together in the future, and an optimized 3D visualization strategy is finally given out. Based on such strategy, the 3D visualization of geospatial information can be accomplished economically and efficiently, thus will meet the requirements of users better.

博士论文摘要

Theory and Methods of Satellite Gradiometry Data Processing

2010, 39(2):  0-145. 

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学术论文

One Ways of InSAR Baseline Detection Based on Formation Satellites

2010, 39(2):  0-145. 

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In the InSAR system based on formation-flying satellites，because the relative position of each satellite participated in formation moves continuously and need a credible way to measure accurately, which is Interaerocraft baseline measurement and baseline estimation. In spite of anyway, the error must be exist. On the processing of the InSAR, baselines are important parameters, and vitally influence the precision of the height of ground point. Baseline is important in InSAR processing, and which is the important factor and decide the chose of interferometric image twins, and be helpful to flat domino effect. Baseline precision decides the last result for InSAR processing. No hi-precision baseline, and no hi-precision DEM. Baseline detection is one of important ways to get high-precision baseline. As yet, the work has not been done in our country, so there are not experiences to use for reference and there is little record in the overseas. This paper studies the baseline detection in the formation-flying satellites. Baseline detection deal with the baseline parameters which is hi-dynamic and distributed by using the hi-precision ground area data. By analyzing and comparing many baseline accurately estimation model, I deduce an advanced-model of baseline estimation based on baseline linear fitting. The tests of baseline detection have been done by using the ERS real data. The result shows the baseline precision has been advances greatly, so the way has practicality very much.

The Mean Squares Error Matrix of Inequality Constrained M-Estimate and the Conditions of Improved Solutions

2010, 39(2):  0-145. 

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When lack of exact prior information, it is possible to use inequality constraints for improving solutions. To inequality constrained M-estimate (ICME), this paper derives the linear representations of the parameters estimator, residuals vector and adjusted vector of observations by using Bahadur linearization principle and aggregate function method. The corresponding variance-covariance matrix (VCV) and the mean squares error matrix (MSE) are also obtained. The Bahadur linear representation shows that the ICME is biased. The MSE matrix says the possibility that the solutions are improved, the condition of the improved solutions is that the maximum of the absolute inequality is smaller the derived threshold that is determined by the first and second nuisances, , ,of M-estimate and the nuisance ； To the least p-norm estimate in the case of Gauss distribution and p-norm distribution, the clear improvement conditions are given out. The derived forms and conclusions can be used for statistical analysis and inequality design.

An approach for Simulating SPOT True Color Image Based on Spectral Library Data

2010, 39(2):  0-145. 

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In this paper a new method of high spatial resolution remote sensing image true color simulation is proposed. This method uses Spectral Angle Match (SAM) model according to the characteristic of surface features from the point of view of remote sensing imaging spectrum. Firstly, overall and partial spectral vector angle between spectrum of pixels and spectral library in green (G), red (R), near infrared (NIR) and short-wave infrared (SWIR) band is calculated. Secondly, the most similar spectral curve is searched in the spectral library according to the minimum distance function which is established on the angle distance. Finally, the reflectance of pixels in the blue band is calculated based on the spectral curve integration. Experiments show that the proposed method is better than traditional methods both in visual effects and spatial information.

Construction of MGeoSALL: a Hybrid BRDF Model for Analysis of Discontinuous Vegetation Canopies

2010, 39(2):  0-145. 

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Compared with the traditional remote sensing, multi-angle obersvation could get the detailed three-dimensional structural information of forest through different directional observations, which provides a new method for quantitative remote sensing. In this paper, an MGeoSAIL model, which was more suitable for multi-angle observations, was constructed based on the improvement of the single-angle model GeoSAIL. The MGeoSAIL model combined the geometric-optical model with the radiation transfer model. Therefore, it had the advantages of the two models, which made it be more accurate and practicable. The geometric-optical model calculated the amount of shadowed and illuminated components in a scene, while the radiation transfer model (SAIL) calculated the reflectance and transmittance of the tree crowns. The reflectance of each component in a scene is weighted by its fractional area and summed. The simulation result showed that the MGeoSAIL model could be simply applicable to describe both the "hot" spot in visible and near-infrared bands and the "bowl" shape in the near-infrared band. Furthermore, this model was demonstrated to be more suitable in the BRDF simulation of discontinuous and open forest with low density and large individuals.

POS-supported Matching Method for Aerial Images between Neighboring Strips

2010, 39(2):  0-145. 

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A novel matching method is proposed for the aerial images between strips by the use of exterior orientation parameters obtained via a position and orientation system (POS). Firstly, the images within a strip are matched using the pyramid image matching method, to obtain the precise image coordinates of tie points. Secondly, the approximate positions of tie points between neighboring strips are predicted with the help of the image exterior orientation parameters obtained via the POS. Thirdly, the image geometric distortions to be matched window in neighboring strip are corrected, and the corresponding points are directly searched on original images under the epipolar geometrically constrained condition. And finally, least square image matching algorithm is performed in order to refine the image matching results to the sub-pixel order accuracy. Experiments have shown that compared with the conventional tie point transfer method between strips, POS-supported image matching method not only simplifies the procedure of image matching and increases the level of automation, but also improves the image matching success rate by 34.0% and save the CPU consuming time by 76.7%.

Least Square Matching Methods for Wide Base-line Stereo Images Based on SIFT Features

2010, 39(2):  0-145. 

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Some new feature extraction and matching algorithms (especially the scale invariant feature transformation algorithm, SIFT) that are invariant to translation, scale and rotation changes have been widely used in digital photogrammetry and computer vision fields. However, SIFT features are not invariant to affine deformation, and the location precision may be low because the feature extraction and matching are independent. In practical applications, this disadvantage makes it not appropriate for wide base line stereo matching. In order to solve this problem and to make it invariant to affine transformation, a new SIFT features’ matching algorithm based on duplicate constraints and least squares image matching method was proposed in this paper. In this algorithm, the optimal SIFT features with good spatial distribution and large information content was first selected, then these SIFT features was matched by using SVD-SIFT algorithm and adaptive NCC matching method based on scale and orientation information of SIFT features. The fundamental and homography matrix can be estimated by using these initial correspondences. Other SIFT features were matched by using duplicate geometric constraint and weighted least squares matching with multiple scale template window. At the same time, the least squares matching results were selected according .Further, by compared to the location error of the original SIFT key points, least squares matching results were determined to adopted or not. Last, two wide base line image sequences were selected to test the performance of proposed algorithm. Test results indicate that the proposed method has higher performance than the original SIFT methods and the SVD based SIFT methods. So the application fields of the SIFT algorithms was greatly extended and a feasible method for wide base line feature matching was provided.