Table of Content

20 November 2014, Volume 43 Issue 11

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Airborne Gravimetry in Bohai Bay and Its Role on the Refining of the Regional Marine Geoid

SUN Zhongmiao ZHAI Zhenhe XIAO Yun

2014, 43(11):  1101-1108.  doi:10.13485/j.cnki.11-2089.2014.0174

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Offshore airborne gravity plays very important role in the unifying of the land geoid and marine geoid. Airborne gravimetry using Chinese airborne gravimetry system is flown in Bohai bay in recently three years, which the surveying area extends about two hundred thousand square kilometers and 5??5? grid mean gravity anomaly has been obtained. The gravimetry is summarized and its key processing method is introduced firstly. Then, we discuss the accuracy estimation methods for the airborne gravity in detail, and introduce so-called grid-overlapping method to appropriately evaluate the internal accuracy of the grid mean gravity anomaly. The results indicate that the standard derivation of the crossover errors is about 1.5mGa1 at the resolution of 5 arcmin, the standard deviation of the 5??5? grid mean gravity anomaly evaluated by grid-overlapping method is about 1.6mGal, and the accuracy of the 5??5? grid mean gravity anomaly are both better than 3.0mGa1 compared with the satellite altimetry gravity data and the seaborne gravity data respectively. The systemic error and the standard deviation of the 1??1? mean airborne gravity compared with the GOCE gravity field model are less than 0.5mGal and about 2.7mGal respectively. The accuracy of the regional geoid using airborne gravity data in the surveying area is improved to 12cm, whereas it is about 23cm computed from EGM2008 model.

The Precise Flight Trajectory Tracking Approach of Altitude Vehicle in Unpowered Phase

ZHAI Guojun BIAN Guanglang SUN Junliang LI Liandeng XIANG Shulin TONG Yan

2014, 43(11):  1109-1117.  doi:10.13485/j.cnki.11-2089.2014.0177

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How to accurately track the flight trajectory of altitude vehicle at unpowered phase is the hot and tough problem in the field of space measurement and control. Based on the analysis of forces acting on the flight vehicle, its rigid movement state equation has been established, and the quality control scheme has also been put forward adopting hierarchical clustering technique to figure out the precise position of impact point. The feasibility and effectiveness of the suggested quality control scheme has been illustrated by simulated example, in which the influence caused by air drag, gravity and iterative step has been researched. The conclusion shows that the flight trajectory of altitude vehicle at unpowered phase could be accurately calculated with offered mathematics model, and the impact point could be automatically estimated.

Two-way Satellite Carrier-phase Time and Frequency Transfer and Its Error Analysis

JING Wenfang LU Xiaochun LIU Feng WANG Jin ZHAO Danning

2014, 43(11):  1118-1126.  doi:10.13485/j.cnki.11-2089.2014.0175

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TWSTFT theory based on the code pseudo-ranging and the error in which is analyzed. For the code rate limited, the precision of the system is difficult to be promoted. So, the TWSTFT based on the carrier-phase measuring is presented, which can enhance the precision more for the high frequency and short wave of the carrier. And the error source in the carrier-phase measuring TWSTFT is analyzed in the paper, result shows that the major source is the errors caused by ionosphere, transponder, and the relative moving between the earth station and satellite.

Apparent inter-frequency clock bias of COMPASS system

LI Haojun ZHU Weidong

2014, 43(11):  1127-1131. 

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It is very meaningful for modeling the inter-frequency clock bias (IFCB) and assessing the stability of the satellite clock to analyze the characterization of the IFCB. The triple-frequency data from COMPASS covering Jan.1-31, 2012 is processed to compute the IFCB of the GEO satellite. To reduce the influence of the gross error on the computed results, the robust estimation is used in data processing. Based on the estimated results, the IFCB series of the GEO satellite is analyzed. According to the features of the IFCB of the GEO satellites, an empirical model is presented. The performances of the model indicate that the quadratic function can describe the IFCB of the COMPASS GEO satellite well, by which more than 71% inter-frequency clock bias can be corrected.

Multi-GNSS Joint Precise Orbit Determination of BeiDou Navigation Satellites System

LIU Weiping HAO Jinming LI Jianwen CHEN Mingjian

2014, 43(11):  1132-1138.  doi:10.13485/j.cnki.11-2089.2014.0186

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Precise?orbit?productis?very?important?for?application?of?BeiDou?Navigation?Satellite?System.A?method?of?zero-differenced?multi-GNSS?joint?precise?orbit?determination?of?BeiDou?satellites?based?on?ambiguity?fixing?is?present.?The?realization?of?ambiguity?fixing?is?focused?on.?

The?real?data?is?analyzed,?and?the?results?show?that?the?three?dimensional?precision?of?GEO,?IGSO?and?MEO?can?respectively?reach?1.263m,?

0.241m?and?0.134m.?The?radial?precision?of?the?three?types?of?satellites?can?averagely?be?better?than?10cm,?and?that?of?IGSO?and?MEO?can?mostly?

be?better?than?5cm.?After?ambiguity?fixing,?the?three?dimensional?precision?of?BDS?is?improved?21.8%?averagely,?and?the?tangential?precision?is?

improved?most?obviously,?especially?for?GEO. 

A General Total Least Squares Algorithm for Three-dimensional Coordinate Transformations

FANG Xing ZENG Wenxian LIU Jingnan YAO Yinbin

2014, 43(11):  1139-1143.  doi:10.13485/j.cnki.11-2089.2014.0193

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The model of three-dimensional coordinate transformation is a nonlinear EIV (errors-in-variables) model. The methods proposed in published literatures are always restricted in practice for their special assumptions, such as size of rotation angles, structured design matrix and special weight matrix. In this paper, a general weighted TLS algorithm of a three-dimensional coordinate transformation is investigated. The new algorithm can be applied in transformations with an arbitrary rotation angles and any applicable weights of the observations, as well as the structured design matrix or the design matrix with both random and fixed elements. The example given in this paper illustrates that this algorithm is general and suits to all kinds of three-dimensional coordinate transformations in practice.

Simplified Autocovariance Least-Squares Method for Constant Acceleration Model

LIN Xu LUO Zhicai YAO Chaolong

2014, 43(11):  1144-1150.  doi:10.13485/j.cnki.11-2089.2014.0143

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Adaptive “current” statistical model algorithm is not the really adaptive target tracking algorithm, the performance of the algorithm depends on the key parameters. In this paper, the maneuvering targets are modeled by the constant acceleration model, and considering the special structure of the process noise covariance matrix, a simplified autocovariance least-squares method is proposed to estimate noise covariances. And this method establishes a relationship between the autocovairnace of the innovation and the unknown covariances, thus, the noise covariance can be estimated by the least-squares method. The simulation results show that, when the maneuvering targets with unit-step acceleration or variable acceleration, the accuracy of the proposed method is better than the adaptive “current” statistical model algorithm.

Performance Comparison between Different Klobuchar Model Parameters

WANG Fei WU Xiaoli LI Yuxiang

2014, 43(11):  1151-1157.  doi:10.13485/j.cnki.11-2089.2014.0176

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To GPS single-frequency user, the ionospheric delay is one of the most important sources of errors. GPS uses Klobuchar model to correct the ionospheric delay whose corrections come from 370 groups of constants derived from empirical models and historical data. Currently stations distributed all over the world can provide ionosphere monitoring results with high precision, why GPS doesn’t broadcast Klobuchar model parameters calculated with observed data? This article focuses on this question. Firstly estimating the precision of predicted global ionosphere maps, COPG, provided by Center for Orbit Determination in Europe (CODE). Secondly we fit the Klobuchar model parameters with COPG. Then we assess the parameters’ precision with global ionosphere maps provided by IGS. Finally we do single point positioning using different Klobuchar parameters to evaluate their influences on GPS single-frequency users. Results show that restricted by Klobuchar model with 8 parameters, precision of parameters fitted using global observed data is just equal with GPS broadcast parameters, both around 55%. On the other hand, precision of model parameters fitted using data on the north of geomagnetic latitude 45oS is much higher, which arrives about 65%, but it performs no better in positioning of single-frequency users. Results in this article provide reference to ionosphere modeling of our nation.

Block Adjustment for ZY-3 Satellite Standard Imagery Based on Strip Constraint

ZHANG Guo WANG Taoyang LI Deren TANG Xinming JIANG Yonghua PAN Hongbo ZHU Xiaoyong

2014, 43(11):  1158-1164.  doi:10.13485/j.cnki.11-2089.2014.0179

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Taking into account that long strip satellite images have the same error distribution characteristics, we propose a block adjustment method for ZY-3 satellite standard imagery based on strip constraint. First, image point coordinate is calculated in strip coordinate system according to offset value of the adjacent image; Second, RFM of strip image is regenerated by RFM of single images, while generating compensation grid; Third, block adjustment for strip image is implemented based on RFM with affine transformation parameter; Finally, affine transformation parameters of single images are recalculate by the affine transformation parameters of strip image. Experiments of ZY-3 satellite imagery show that block adjustment for satellite imagery based on strip constraint (strip adjustment) can achieve a better result than block adjustment for satellite imagery based on single image under the condition of sparse control. The planar and vertical accuracies of 2.504m and 3.117m in Taihangshan and 2.504m and 3.117m in weinan, respectively, with 6 GCPs. The test results demonstrate the effectiveness and feasibility of the method

An Inner FOV Stitching Method for Non-collinear TDI CCD Images

PAN Jun HU Fen WANG Mi JIN Shuying LI Guoyuan

2014, 43(11):  1165-1173.  doi:10.13485/j.cnki.11-2089.2014.0180

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High-quality inner FoV (field of view) stitching is a necessary step for post-process and application of images captured by spaceborne non-collinear TDI CCD camera. This paper presents an inner FoV stitching method for non-collinear TDI CCD images. The method utilizes the projection plane in object space and the sensor geometric model of the camera to establish the coordinates transformation relation between pixels of the stitched image and pixels of the orginal image, and then performs image resampling to generate the stitched image by indirect image geometric rectification. After describing the strict geometric models of non-collinear TDI CCD images, the basic principle, the potential error sources and the workflow of the method are discussed in detail. Finally, experimental verification is carried out on the high-resolution (HR) camera images of ZY-1 02C satellite, and the accuracy evaluation of the generated stitched images indicates the feasiblity of the presented method.

Georegistrationof Ground Sequential Imagery with Geo-referenced Aerial Images in High Noise Environments

JI Shunping SHI Yun

2014, 43(11):  1174-1181.  doi:10.13485/j.cnki.11-2089.2014.0181

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A Monte-Carlo georegistration method (MCG) is presented to solve the global localization problem of a ground mobile vehicle with car-mounted panoramic sequential imagery and geo-referenced ortho-images. Firstly, a general stochastic localization model is deduced according to Bayes rules and Markov chain under the two constraints of geometry and radiance. Then a particle filtering method called Monte-Carlo is introduced to solved the localization model, considering the difficulties of multi-source matching between pano-images and ortho-images caused by shadows, occlusions, moving objects etc., and achieves the matching and geo-referencing simultaneously. A localization test with more than 2000 pano-images and one ortho-image with 0.25m accuracy proved that MCG can tolerate excessive blunders more than 80% caused by mismatching and obtain a high localization accuracy approaching BA results with full GCPs.

Graph based Semi-Supervised Learning with Class-Probability Distance for Hyperspectral Remote Sensing Image Classification

SHAO Yuanjie WU Guoping MA Li

2014, 43(11):  1182-1189.  doi:10.13485/j.cnki.11-2089.2014.0182

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A class-probability distance based semi-supervised learning method is proposed for hyperspectral remote sensing image classification. In the method, Sparse Representation based Classification (SRC) is adopted for estimating the class-probability of unlabeled sample. Then a distance metric that describes the data similarity is developed based on the estimated class-probability. With this new distance metric, the distance between samples of different classes is enlarged effectively, and the neighbors of each sample can contain more samples belonging to the same class. Finally, this distance metric is applied to Linear Neighborhood Propagation and Label Propagation algorithms. Experimental results using Hyperion and AVIRIS hyperspectral remote sensing images show that the approach outperforms the existing semi-supervised learning methods in terms of classification accuracy.

Accessibility Analysis of Road Network Supported by Isochrone Model

HE Yakun AI Tinghua YU Wenhao

2014, 43(11):  1190-1196.  doi:10.13485/j.cnki.11-2089.2014.0183

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An isochrone is a visual representation of time accessibility which refers to a particular point in the road network. Features of road network and traffic conditions should be considered when generating isochrones. Accessibility rules can be found through analyzing the morphological features of isochrones. This article systematically studied the definition, characteristics and generation methods of isochrones. We proposed the flow method to generate isochrones, which was analogous to the process of water drop spreading along the wood texture. Accessibility expansion paths were obtained on the basis of the network rasterization model, considering unique constraints of isochrones extension, such as road conditions, moving criteria and time sections. Then we used the extending convex hull and angle bisector displacement to generate isochrones. Since the algorithm was based on field theory, we could flexibly load space constraints for any part of interested zones. This advantage made it convenient to generate real-time isochrones. Similar to extracting geomorphic traits from contour lines, we found accessibility rules by analyzing the arrangement form, density, bending form, bending direction and stretching direction of isochrones which was generated by the above approach. After that, we inferred accessibility rules.

A Hybrid Algorithm for Traveling Salesman Problem in Road Network

YU Li

2014, 43(11):  1197-1203.  doi:10.13485/j.cnki.11-2089.2014.0184

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Traveling salesman problem is one of the classic network analysis problems. Due to it is NP Hard, people mainly take optimization method or heuristic algorithm to obtain the approximate optimal solution. However, single heuristic algorithms have some drawbacks, such as large computational complexity, rigorous parameter selection, strong dependence for the initial value and so on, which are difficult to quickly achieve whole optimization. Hybrid heuristic algorithm can solve this problem to some extent, which combines with a variety of optimization mechanisms and structures of neighborhood search. Considering the global optimization ability of genetic algorithm and the memory function of tabu search, this paper designed and implemented a tabu genetic algorithm based on decentralized and centralized strategy. Genetic mutation operator as a decentralized strategy was used to construct neighborhood, which exploited the new search space and enhanced the probability to obtain the global optimal solution. Tabu search as a centralized strategy was used to local search, which avoided circuitous detection and embodied the powerful "mountain climbing" ability. Moreover, this paper evaluated the algorithm from three aspects of accuracy, stability and efficiency using different scale of traffic network data. The results show that the tabu-genetic algorithm has higher accuracy which is increased by 9% than the tabu search algorithm, when the accuracy error is within 1%. And it can reduce the time consumption over 50% compared with genetic algorithm. Moreover, the tabu-genetic algorithm has the potential of parallelism.

A Multi-constraints Displacement Method for Solving Spatial Conflict between Contours and Rivers

LI Guohui XU Wenshuai LONG Yi ZHOU Tong GAO Chao

2014, 43(11):  1204-1210.  doi:10.13485/j.cnki.11-2089.2014.0189

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In the process of spatial data integration and matching, the inconsistency often occurs between the rivers and contour lines that generate some spatial conflicts just like “river climbing slope”. Aiming to solve the problem by displacing the contours to matching the river network, this paper put forward a new method for every feature point on contour lines to establish specially its displacement model by affine transformation. The method comprehensively considered relative positions of adjacent ridge and valley points, the angle proportion of different feature points for displacing and local shape of contours to be maintained and transformed, so that the calculation of three constrained parameters determine the displacement of points on the contours that is angle, location and scaling was proposed. To test the method, several experiments were taken to analysis. The results showed that the research can effectively complete the displacement of contour lines to match the river network.