Acta Geodaetica et Cartographica Sinica

Collocation Model Based on Regional Tectonic Features in Crustal Deformation Analysis

2011, 40(4): 0-441.

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Collocation method, when applied to crustal deformation analysis, can estimate the deformation trend reliably not only of the observed points but also of the unobserved points. But if there are faults or hidden faults in the researched area, accustomed collocation is not proper to deformation analysis because of the discontinuous deformation. So collocation based on regional tectonic deformation background is proposed, which divides the area roughly according to geology information and then establishes collocation models respectively in each division. The points near by the boundary are differentiated by confidence interval of deformation parameter. Since the local deformation or abnormal observations may influence the reliability of modeling, robust estimation with high breakdown point is applied to calculate model parameter which is not disturbed by abnormal points. Simulated and practical examples are given and the results prove the efficiency of the proposed method in this paper.

The adaptive filtering by selecting the parameter weights for single antenna GPS/INS loosely coupled model with GPS heading constraint

2011, 40(4): 0-441.

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The main problem of the single antenna GPS/INS coupled model is that the observation information is insufficient, and the state model can not fit a complex kinematic environment，so it is very difficult to estimate the indirect parameters accurately. A new method for improving the filter results is put forward. On one hand, on the motion condition, the heading calculated from the single antenna GPS observations is taken as the virtual observation and added to the observation equation of the kalman filtering; on the other hand, the adaptive filtering by selecting the parameter weights is extended to the GPS/INS integrated system. Through analyzing the gain matrix and position, velocity, platform angle error estimators, the results of the new method are more accurate and reasonable than that of the classical coupled method.

The Principles and Methods of Discrete Global Grid Systems for Geospatial Information Subdivision Organization

2011, 40(4): 0-441.

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China Geodetic Coordinate System 2000: Velocity Field in Mainland China

2011, 40(4): 0-441.

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Abstract: The definition of the China Geodetic Coordinate System 2000 is identical with that of the International Terrestrial Reference System. The realization of the system is accomplished by two steps. As the first step, the combined adjustment of the Crustal Movement Observation Network of China(CMONC), the Nationwide GPS First and Second Order Network, the National GPS A and B Order Network, and the Crustal Movement Monitoring Network is carried out in ITRF97, achieving consistent coordinates of some 2600 GPS geodetic points at epoch 2000.0. As the second step, the velocities of 1070 CMONC stations are obtained through processing the CMONC data of ten years. Furthermore, the velocities of the remaining 1400 non-CMONC stations are interpolated using known velocities of the CMONC stations. This paper is devoted to the second step of the realization of the system, namely, to studying the determination of the velocity field in mainland China. The results of the velocity field for the mainland China are presented. Four methods for the utilization of the velocity field are proposed, which are the regional Euler vector method, the local Euler vector method, the grid mean value method and the block Euler vector method. The advantages and disadvantages of individual methods are compared and analyzed in terms of the accuracy of velocity and the convenience of use. A 3°×3°grid mean velocity table for mainland China is appended for user's reference.

Analysis of Inequality Constraints Influence to Adjustment Results

2011, 40(4): 0-415.

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Inequality constrained adjustment model can improve the result and it is used more and more in geodesy. Many algorithms were proposed to estimate the unknown parameter, but the affect of inequality constraints to adjustment and the statistical properties of the parameter have been not solved yet. As to this problem, we proved that the inequality constrained adjustment is a biased estimation and the expectation and covariance are given based on statistics. Compared with unconstrained adjustment, we proved that the covariance of inequality constrained adjustment is always smaller than that of unconstrained adjustment. A simple example is given to demonstrate the four statistical properties of inequality constrained adjustment. Meanwhile we concluded that it is not proper to treat active constraints as equality constraints to assess the accuracy.

An Emergency Evacuation Routing Optimization Method Based on Spatio-Temporal Congestion Concept

2011, 40(4): 0-441.

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The paper proposes a concept of space-time congestion to describe the congestion level of moving objects in time and space dimensions. Based on this concept, an emergency evacuation route optimization method is proposed. This method has the capability of providing an integrated solution for the evacuees to evacuate from their locations inside of buildings to the safe areas passing by road networks. This paper analyses the space-time congestion in the evacuation process based on the Dijkstra’s shortest path algorithm, and then optimizes this plan by virtue of resolving congestion and reducing the clearance time of the overall evacuation process. Experimental testing of this proposed method shows the optimized plan can ease the congestion of the evacuation plan systematically, and provide a relatively reasonable evacuation path for every single evacuee.

Approximate Analytical Formula for Variances of the First and Second Radial Derivatives of GOCE Tzz

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2011, 40(4): 0-441.

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In order to analyze the height to be ignored for the continuation of GOCE satellite gravity gradient (SGG), the variances of the first and second radial derivatives of SGG usually need to be calculated. In this paper, approximate analytical formula for variances of the first and second radial derivatives of GOCE Tzz are derived based on Kaula’s rule. From the derived formula, the height to be ignored for the continuation of GOCE Tzz is estimated. It shows that the formula of the variances of the first and second radial derivatives can be expressed approximately by square root of linear combination of a series of Gamma functions, the estimated variances are about 1.269×10-15s-2m-1 and 1.109×10-20s-2m-2 respectively for GOCE satellite. To meet the precision requirement of 1mE, the heights to be ignored for GOCE first and second radial derivatives are less than 0.8km and 7.6km respectively. A numerical calculation by using strict formula for the variances of first and second radial derivatives from simulated GOCE orbits is performed. The results show the proposed approximate analytical formula can reasonably evaluate the variances , and their relative errors are all less than 2%, which proves their validation and correctness.

An Auto Retrieval Method of Geographic Event Information Based on Ontology

2011, 40(4): 0-441.

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It is difficult for existing systems to organize spatial information according to geographic event and not to provide initiatively the spatial information correlative to event disposal to the users. Users often need to operate multi-source isomerous applied system so as to get the information with fussy course and lower retrieval efficiency. In this paper, we propose an auto retrieval method of geographic event information based on ontology other than traditional geographic information retrieval by using the key to make match and inquire, in which the geographic event is regarded as the tache. Therefore, users only need to know the elementary information of geographic event and can extract intellectually the information associated with geographic event from large spatial information database and provide the individuation support of retrieval. So, the retrieval information can be made by users automatically with simplified course of information access, information organization and applied model of software. And finally, the retrieval efficiency can be enhanced.

Study on Determination of the Earth’s Gravity Field from Satellite Gravimetry Mission GOCE

ZHONG Bo

2011, 40(4): 0-441.

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Remote sensing image fusion using multi-scale spectrum gain modulation

2011, 40(4): 0-441.

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When the classic methods, such as IHS (Intensity-Hue-Saturation) transform, PCA (Principal Component Analysis) transform, etc., are employed in image fusion, the color distortion problem will appear due to the change of saturation. To solve this problem, this paper proposes a multi scale spectrum gain modulation (SGM) image fusion method, which is based on the spectrum gain surface (SGS) and can avoid the color distortion relating to the change of saturation, so as to preserve the spectrum. The result image of this method can provide high definition and high fidelity of spectrum. The experimental results and objective evaluations indicate that, compared to the conventional image fusion methods (IHS, PCA，etc.), the proposed method can obtain the better tradeoff between improving the spatial resolution and preserving the spectral characteristics, and is applicable to the occasion where the high fidelity of spectrum is required.

A Novel Spatial Clustering Method Based on Multi-Constraints

2011, 40(4): 0-441.

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Spatial clustering has played an important role in spatial data mining and spatial analysis. It aims to classify the spatial entities in a database into some meaningful clusters, where entities are similar to one another in same clusters and are dissimilar to the entities in different clusters. In practical applications, spatial clustering algorithm can be used to discover clusters in the spatial database with complicated structures, such as clusters of uneven density, clusters of arbitrary shape, clusters adjacent to each other, and clusters with significant outliers. In the meantime, it is also required that entities in a same cluster should be both nearest in spatial domain and very similar in thematic attribute. For this purpose, a novel multi-constraints based spatial clustering algorithm is proposed in this paper. Delaunay triangulation is first employed to determine the spatial proximate relationships among entities, and then multi-levels constraints are utilized to discover clusters in the spatial database. The presented algorithm is tested on both simulated and practical spatial databases, and its advantages over some well-known algorithms are also fully highlighted.

3D Reconstruction and Inspection of Cylinder based on Geometric Model and Generalized Point Photogrammetry

2011, 40(4): 0-441.

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Based on the cylinder geometry model and generalized point photogrammetry, with the ellipse detection by curve segments, an automatic 3D reconstruction and error detection method of cylinder was proposed without any priori knowledge abort spatial location or dimension parameters. This paper deduced the mathematical adjustment model based on cylinder geometry model and generalized point photogrammetry, and gave the method of calculating initial parameters. The experiment with the actual cylindrical industrial parts images got by calibrated stereo cameras reveals the proposed method’s efficiency. And this method can be extended to the 3D reconstruction of other industrial parts with basic mathematical models easily.

A New Algorithm for Creating Slope Lines with no Intersections

2011, 40(4): 0-441.

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This study develops a new algorithm to create any kinds of slope lines with no intersections automatically. It gives enough evidence to support that the Real-intersection and the Complementary theorem proposed in this research are sufficient conditions of the generation of slope lines without any intersections. This method can dynamically draw any kind of normal-based slopes, scarps, escarpments, steep rock hills or embankments. The efficiency of the algorithm is tested by using three experiments.

Research on Algorithm of Shelter Assignment Based on Capability Limitation and Optimization of the Travel Cost

2011, 40(4): 0-441.

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According to the residence evacuation plan for the city emergency, an algorithm for distributing the shelter for victim or spatial disaster cell is proposed based on shift insertion method in this paper. Considering the uneven distribution of the residents in space and the capability limitation of each shelter, the proposed algorithm minimizes the total travel cost and keeps the spatial service continuity of each shelter with capability constraint. As a result, it can provide the scientific basis and the decision support for emergency evacuation. Comparative experiments under different constraints in the paper have evaluated the algorithm’s availability and feasibility. Moreover, applications in engineering projects also prove the excellent practical utilities.

Adaptively Changing Reference Station Algorithm and Its Application in GPS Long Range Airborne Kinematic Relative Positioning

WANG Qian-Xin ¹, XU Guo chang³

2011, 40(4): 0-441.

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The single baseline model is the simplest and common solution model in kinematic relative positioning. However, such a model is generally not suitable for the long range airborne positioning. Due to the long distance between reference station and kinematic station, many kinds of common errors can not be cancelled out by the differential method. And the number of common satellites will decrease with the increase of baseline length. In this paper, a method of adaptively changing reference station is developed. The basic idea is that the reference station will be automatically replaced by the nearest one, when the distance between kinematic station and original reference station is longer than the maximum distance defined by user. The method of equivalently eliminating parameters is used to combine the observation data between new and original reference stations. To verify the validation of this method, GPS data of airborne campaign AlpinAero2008 is used. The results show that the proposed method can provide a more stable and consistent solution of kinematic positioning with about 2cm precision level compared with those of the network solution.

An Adaptive Method for 3D City Model Based on Extended 3D R-Tree

2011, 40(4): 0-441.

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An adaptive control method of LOD for 3D city model is one of key scientific issues. Aiming at the requirement of large-scale 3D city modelling, this paper puts forward a method to organize LOD models based on R-tree’s hierarchical structure. LOD models can be automatically generated from leaf node layer to root node, and efficient algorithms of view-frustum query and LOD model search are also designed and implemented. By experimental analysis, it is proved that scene complexity can be quantitatively altered by adjusting one defined LOD parameter, and further adaptively control LOD of 3D model visualization, which suits building type especially.

A Shape Multilevel Description Method and Application in Measuring Geometry Similarity of Multi-scale Spatial Data

2011, 40(4): 0-441.

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The paper establishes universal measure model of geometry similarity for multi-scale spatial data based on multilevel chord length functions and center distance functions. These functions can describe geometry shape from entirety to part gradually. This paper improves the traditional Hausdorff distance based on the statistic Gaussian mode. The enactment of every criteria threshold value in the measure model of geometry similarity is solved by introducing relevance feedback techniques. At last, the model is applied in data matching of different scales and similarity measure of spatial object simplification. Experiments show that the model can realize the matching and similarity measure effectively in waters data of different scales.

Calibration of slant Total Electron Content (sTEC) and satellite-receiver’s Differential Code Biases (DCBs) with uncombined Precise Point Positioning (PPP) technique

2011, 40(4): 0-441.

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The ionospheric observables can be determined by combining dual-frequency observations of GNSS through carrier-to-code leveling process, which mainly include the slant Total Electron Content (sTEC), satellite-receiver’s Differential Code Bias (DCB) and can be applied for ionosphere related research. However, the “leveled carrier phase ionospheric observable” is prone to be influenced by the arc length for leveling and receiver-dependent errors. In this contribution, an approach of calibrating sTEC and satellite-receiver’s DCB with ionospheric observables estimated with uncombined Precise Point Positioning (PPP) is proposed. With a short-baseline experiment, the sTEC determined with both kinds of ionospheric observations from one receiver were used to correct the corresponding observations of another receiver and single frequency PPP was implemented, the positioning results indicated a better reliability of sTEC calibrated with PPP-based ionospheric observables. Furthermore, by choosing a total of 4 days’ observations from 8 global-distributed IGS tracking stations (i.e. 4 days of Jan. 2009), all the satellites’ DCB are solved and compared with the products published by CODE, a discrepancy of no more than 0.1 ns can be found for PPP-based ionosheric observables in comparison of 0.2~0.3 ns for leveled carrier phase ionospheric observables, thus facilitate the precise study of ionosphere.

A Method of DEM Mapping Facilitated External DEM with High Resolution InSAR Data in Complex Terrain Area

2011, 40(4): 0-441.

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In order to fulfill the request of Digital Elevation Model (DEM) mapping in complex terrain areas with the remarkable height difference and steep slopes, a DEM refinement Mapping approach is presented in this paper in complex terrain areas with high resolution SAR data. On the basis of Interferometric Synthetic Aperture Radar (InSAR) technology, a coarse external DEM is firstly introduced, the one-to-one correspondence between interferogram and external DEM can be determined. Then multiple linear models are established, the trend of phase error can be removed by linear regression analysis. Moreover, unreliable height points can be effectively filtered once the gross errors are determined via the error range of external DEM. Finally DEM product is constructed from reliable height points. The experiment with high resolution InSAR data of COSMO in deqing areas in China is implemented, the final result has been validated by check points surveyed from GPS, the DEM mapping product has been proved to fulfill the standard of 1:50,000 DEM mapping in complex terrain areas .

Research on the Correlative Extremum Matching Algorithm Using Underwater Gravity Anomalies

2011, 40(4): 0-441.

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Gravity-aided inertial navigation is a technique that makes use of gravity to correct inertial navigation error of underwater vehicles. Matching algorithm is vital in the process of gravity-aided inertial navigation. An object function model of differential descending weight-correlation was put forward based on the principle of mean square deviation. Besides, a probabilistic data association filter algorithm was proposed for multi-available positions that resulted from the disturbing errors of the real position. Compared with choosing the unique position which is closest to the actual one, PDAF promotes the reliability and the robustness of the algorithm. Then, the effect of the serial sampling intervals on the matching precision was discussed. Through simulations in the experimental area, the results showed that navigation errors were corrected effectively with proper sampling intervals and sampling lengths based on the algorithm of this paper.

A Semi-empirical Model for the Correction of Terrain Influences in SAR Backscattering

2011, 40(4): 0-441.

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Synthetic Aperture Radar (SAR) imagery has more and more application in image classification, estimation depth of snow cover, soil moisture and so on. However, the effects of terrain undulations on SAR imagery calibration and those applications are severely. In this paper, a simple semi-empirical model was proposed for the correction of terrain influences in SAR backscattering. Firstly, the calculation model of local incidence angle was derived based on the SAR imaging characteristics. Secondly, the effects of the terrain slop and aspect on the SAR backscattering in three different look incidence angles were simulated by the Advanced Integral Equation Model(AIEM), the results show that low incidence angle SAR data was affected less by the terrain influences, so it is the optimum data for the applications in the topographic relief regions, and there is a good quadratic function relation between the SAR backscattering coefficient and the local incidence angle, and hereby presents the semi-empirical model for the correction of terrain influences. Finally, the semi-empirical model was validated by both of the simulation data and the ASAR data, the correct results show that the semi-empirical model will offer help to the application of SAR data.

Improved Method for Removal of Correlated Errors in GRACE Data

2011, 40(4): 0-441.

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The error of the GRACE potential coefficients increases towards higher spherical-harmonic degrees, and the result of gravity anomalies computed from GRACE data will be dominated by errors such as stripes. Swenson proposed an empirical moving window filtering method to remove the correlation and shows a significant effect in the region on both sides of the equator, but it is not provided more details about the method in the paper. Many people did not get the desired effect followed the principle of Swenson when filtering. In this paper, we improved the technology of data processing and achieved the expected results. More, we calculated the global gravity change trends using GRACE data based on this method. The results can more clearly and reasonably reflect the location of gravity change and prove that the improved method is more reasonable and effective in producing GRACE data

Scale factors in recursion of ultra-high degree and order Legendre functions and Horner’s scheme of summation

2011, 40(4): 0-441.

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