Table of Content

20 July 2016, Volume 45 Issue 7

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Entropy-based Cartographic Communication Models: Evolution from Special to General Cartographic Information Theory

LI Zhilin, LIU Qiliang, GAO Peichao

2016, 45(7):  757-767.  doi:10.11947/j.AGCS.2016.20160235

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Map is a kind of powerful means to help people in understanding the objective world. The key function of map is to transmit spatial information. The measurement of spatial information of maps dates back to 1960s, when the information theory of communication was introduced to the field of cartography. The introduction led to a new branch of cartography, i.e. cartographic information theory. This paper provides a review of the development of cartographic information theory over the past 50 years. Emphasis is on the evolution from the special to the general cartographic information theory.

The Vertical Shift between 1985 National Height Datum and Global Vertical Datum

HE Lin, LI Jiancheng, CHU Yonghai

2016, 45(7):  768-774.  doi:10.11947/j.AGCS.2016.20160029

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The mean geopotential value of the global mean sea surface, 62 636 856.550 7 m²s^-2, is determined based on the global gravity model(EIGEN-6C4、EGM2008) and global mean sea surface height model(DNSC08、DTU10、DTU13).The geoidal potential (62 636 858.179 0 m²s^-2) can be obtained by subtracting the mean sea surface topography from the mean sea surface height. Then, 649 GPS/leveling data,distributed evenly over the mainland of China,are selected to calculate the 1985 national height datum geopotential and the vertical shift using three methods, combined with the global gravity model EGM2008. The vertical shift value is improved by weighting, and utilizing two methods to verify the rationality and correctness after weighting. The final results demonstrate that the 1985 national height datum is 0.298 0 and 0.464 2 m above the mean sea level and the global geoid, respectively.

Optimization Method for Computing Radial Gravity Gradient Using Gravity Gradient Observations

MENG Xiangchao, WAN Xiaoyun, YU Jinhai, ZHU Yongchao, FENG Wei

2016, 45(7):  775-781.  doi:10.11947/j.AGCS.2016.20160007

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This paper proposes an optimization method for computing the radial gravity gradient by using GOCE gradient measurements, based on the variance-covariance information of gradient observations. The approach for computing the gravity gradient and the error propagation are firstly discussed; and then by solving a conditional extremum problem, we can get an optimal combination factor which can improve the calculation accuracy for the radial gravity gradient. The advantage of the combination factor is validated by simulation data. In actual data processing, the geoid accuracy truncated to degree 250 can be improved by 2 cm by using the optimization method. The radial gravity gradient can not only be used in recovering a gravity field model, but also can be used in kinds of geophysical interpretation, so the method provided in the paper can be helpful in the related researches.

A High-precision Correction Method of Ultra-rapid Ephemeris Clock Bias Prediction for GPS Block IIR-M Satellites

CAI Chenglin, HE Chengwen, WEI Zhaochuan

2016, 45(7):  782-788.  doi:10.11947/j.AGCS.2016.20160017

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A high-precision correction algorithm based on the block IIR-M satellites is proposed to improve the precision of IGS ultra-rapid predicted (IGU-P) products. In order to ensure that the real-time precise point positioning (RTPPP) with high positioning accuracy could come true, it is attempted to get the difference between the first prediction data and the last epoch of IGS ultra-rapid observed (IGU-O), and then to compute the value and determine the direction of accuracy revised value based on influence of the degree of residual value to difference sequence of IGU-O. The numerical examples with the data set of 19 IGU files showed that the prediction accuracy of proposed method was superior to three basic models and IGU-P within 6 hours, the rate of improved accuracy range from 3.48% to 6.13%, and average prediction accuracy of corresponding models were, in order,0.599 ns,0.570 ns and 0.531 ns.

Analysis of the Lunar Gravity Field by Using GL0660B Model and Its Effect on Lunar Satellite Orbit

HUANG Kunxue, CHANG Xiaotao, ZHU Guangbin, LI Wudong

2016, 45(7):  789-794.  doi:10.11947/j.AGCS.2016.20150598

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The lunar gravity field provides a way to research moon's evolution and probes the interior structure of the moon. It is an important factor influencing the lunar satellite precise orbit determination as well. The new lunar gravity model GL0660B from GRAIL mission dramatically improves the gravity spectrum and spectral ranges. Using the model GL0660B, it can be computed that the corresponding degree-wise RMS and correlation of topography, with which the quality of model GL0660B can be analyzed. Then different characters of the lunar gravity field comparing with other lunar gravity fields are analyzed. Besides, gravity anomaly distribution figures at different height of the models are given, and the character and difference of the lunar gravity models at different height are compared. In addition, lunar satellite orbit revolutionary at different height are modeled by GEODYN. The result shows that the trend of lunar satellite eccentricity changes is a complex and long cycle of change trend. It is different affected by the perturbation of the mascons of different height, which causes different changes of apolune, perilune and eccentricity.

Improved Water Level Retrieval from Epoch-by-Epoch Single and Double Difference GNSS-R Algorithms

WANG Nazi, BAO Lifeng, GAO Fan

2016, 45(7):  795-802.  doi:10.11947/j.AGCS.2016.20150638

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GNSS-R is a new technology for monitoring the water level with high efficiency. Compared with conventional water level measurement technique, such as satellite altimetry and tide gauges, GNSS-R can observe more reflected points with high temporal and spatial resolution and unaffected by the influence of the plate vertical motion. This paper presented an improved cGNSS-R altimetry algorithm based on single difference to derive the reflector heights epoch-by-epoch, which can enhance the temporal and spatial resolution of surface height measurements, furthermore, the other algorithm based on the double differenced carrier phase measurements was also presented in this paper. By using the observed data of cGNSS-R altimetry experiment conducted on Qinghe bridge of East Lake, Wuhan, the reflector heights between the reflected antenna and the lake surface were given to prove the above mentioned algorithms, and the precision were ±2~±4 cm. The results show that the proposed algorithms based on single and double difference which are used for water level retrieval can sufficiently decrease the influences due to clock error, ionospheric and tropospheric error.

Improved Ionospheric Model Algorithm for LEO Satellite Single-frequency Precise Orbit Determination

TIAN Yingguo, HAO Jinming, YU Heli, LIU Weiping, XIE Jiantao, ZHANG Kang

2016, 45(7):  803-809.  doi:10.11947/j.AGCS.2016.20150628

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Ionospheric delay correction is the core issue of LEO satellite single-frequency precise orbit determination. At present, "the method of ionosphere scale factor" is mainly adopted in the LEO satellite ionospheric delay correction, but the method doesn't consider the electron density peak height along with the variation of factors, such as latitude and longitude, day and night, seasons, solar activity, etc. IRI2012 model while considering the influence of the above factors on the electron density peak height, but because of the height criteria inconsistent with ionosphere single layer model, there is usually a systematic deviation and can't be used directly. Therefore, this paper puts forward to an improved ionospheric delay correction method, the ionosphere thin layer height as the constraint condition of IRI2012 model of electron density peak height of the mean parameter estimation. Based on Swarm satellite single-frequency observation data, the effectiveness of the method was verified. The results showed that: with the improved model of the ionosphere, the precision of Swarm satellite obit radial, tangential and normal was improved in varying degrees, especially for the radial and normal most obviously, improved on average by 31.6% and 32.0%, respectively. At the same time, the systemic deviation of the orbit reduced significantly, especially for the radial and normal, reduced on average by 65.0% and 54.7%, respectively.

Inferring Multi-dimensional Deformation Filed in Xi'an by Combining InSAR of Ascending and Descending Orbits with GPS Data

WANG Xiaying, ZHANG Juqing, ZHANG Qin, ZHAO Chaoying

2016, 45(7):  810-817.  doi:10.11947/j.AGCS.2016.20150485

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According to the character that InSAR observations are insensitive to deformations of north direction, it is proposed that inferring three dimensional deformations by combing north-south deformation field from GPS interpolation with InSAR results.The proposed method effectively avoids the effects of ignoring north-south deformation information, well improves the accuracy of vertical deformation. Taking the Xi'an city as the research area, combining EnviSat ASAR, ALOS PALSAR and GPS data, inferring absolute deformation rate filed of east-west and vertical directions, contrast of the deformation with 11 leveling points shows that the integration not only be capable of providing three dimensional deformation field but also attain more accurate vertical results compared with ignoring north-south deformation. The result will help acknowledge the Xi'an geological background.

A StereoSAR Matching Method Based on Disparity Maps Fusion

WANG Yachao, ZHANG Jixian, HUANG Guoman, LU Lijun, DING Hao

2016, 45(7):  818-824.  doi:10.11947/j.AGCS.2016.20160040

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A matching algorithm based on disparity maps fusion is proposed. Firstly, on the basis of normalized cross correlation(NCC), various disparity maps are computed using several different matching window sizes. Then, for each disparity of each disparity maps, the confidence level is evaluated by a new confidence measure, which combined left right consistency(LRC) with signal to noise ratio(SNR). Finally, a new proposed disparity maps fusion strategy is used for formation of weighted disparity map in terms of confidence level. This disparity maps fusion strategy considers not only the confidence level of the disparity itself but also its neighbors. The algorithm has been applied to a pair of TanDEM-X spotlight stereo images. The results demonstrate that the accuracy of DEM generated with the proposed algorithm is improved from 11.28 m to 8.41 m and the gross errors are effectively reduced.

Applying Spatial Statistics into Remote Sensing Pattern Recognition: with Case Study of Cropland Extraction Based on GeOBIA

MING Dongping, QIU Yufang, ZHOU Wen

2016, 45(7):  825-833.  doi:10.11947/j.AGCS.2016.20150520

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Information extraction from remote sensing image is the key to remote sensing applications and scale selection is one of the key factors influencing the information extraction accuracy. This paper discusses the theoretical foundation of applying spatial statistical methods to resolve the scale related issues involved in remote sensing pattern classification. Aiming at geo-object-based image analysis (GeOBIA), scale parameters involved in multi-scale segmentation for GeOBIA are generalized into three ones, and they are spatial parameter, attribute parameter and merging threshold. Further, the pre-estimation method of the optimal scale parameters is proposed based on spatial statistics. Taking GeOBIA based cropland extraction from SPOT-5 image as an example, this paper proposes a cropland extraction method combining spatial statistics based adaptive scale parameter pre-estimation and object-oriented classification. This paper employs mean-shift segmentation and series Rof object based classification on different scales to verify the validity of this method. Experimental results support the object based cropland extraction method based on the data-driven scale pre-estimation. The cropland extraction result by using the pre-estimated segmentation parameters can guarantee the accuracy of GeOBIA classification and the cropland extraction based on GeOBIA and adaptive scale pre-estimation avoids the time-consuming trial-and-error practice and speeds up the object-oriented classification procedure.

Scene Classification of Remote Sensing Image Based on Multi-scale Feature and Deep Neural Network

XU Suhui, MU Xiaodong, ZHAO Peng, MA Ji

2016, 45(7):  834-840.  doi:10.11947/j.AGCS.2016.20150623

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Aiming at low precision of remote sensing image scene classification owing to small sample sizes, a new classification approach is proposed based on multi-scale deep convolutional neural network (MS-DCNN), which is composed of nonsubsampled Contourlet transform (NSCT), deep convolutional neural network (DCNN), and multiple-kernel support vector machine (MKSVM). Firstly, remote sensing image multi-scale decomposition is conducted via NSCT. Secondly, the decomposing high frequency and low frequency subbands are trained by DCNN to obtain image features in different scales. Finally, MKSVM is adopted to integrate multi-scale image features and implement remote sensing image scene classification. The experiment results in the standard image classification data sets indicate that the proposed approach obtains great classification effect due to combining the recognition superiority to different scenes of low frequency and high frequency subbands.

Land Observation Evaluation of Effective Coverage for Optical Satellites Based on Physical and Meteorological Condition

WU Zhaocong, WU Yuan, ZHANG Yi, YANG Fan

2016, 45(7):  841-849.  doi:10.11947/j.AGCS.2016.20150381

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The coverage evaluation of traditional land observation for optical satellite is based on ideal coverage of satellite, which has no consideration of the influence of physical condition, such as satellite storage, satellite data transmission and observation time. It also has no consideration of the influence of meteorological condition in observation area. According to land observation requirements of remote sensing, an index evaluation system of effective coverage ability for remote sensing on land observation is build up. According to data storage capacity, data transmission capacity between satellite and ground, longest observation time in one loop, solar elevation angle of satellite observation and so on, an effective coverage calculation method is proposed based on physical capacity constraint for optical remote sensing satellite. On the basis of the climate data of meteorological station over the years, an effective coverage calculation method based on climate constraint is raised for optical remote sensing satellite. Synthesizing satellite physical capacity constraint and climate constraint, effective coverage capacity of earth observation for optical remote sensing satellite is calculated. Meanwhile, based on index evaluation weight of effective coverage capacity for land observation by experts, analytical hierarchical process (AHP) is used to evaluate requirement satisfactory degree for land observation. The experimental result shows that the proposed algorithm is more accurate in estimation and evaluation for effective coverage on land observation, which is able to provide a more precise solution for effective coverage capacity evaluation on earth observation.

The Collaborative Method of Linear Graphic Simplification and Displacement

GUO Qingsheng, WANG Lin, SUN Yageng, ZHOU Lin, LONG Yi

2016, 45(7):  850-857.  doi:10.11947/j.AGCS.2016.20150513

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Linear graphic simplification and displacement operators are usually performed respectively in map generalization. Both of them may give rise to new conflicts with other map features such as surrounding buildings. In this paper, we attempt to coordinate these two operators to avoid repetitious detection of spatial conflicts, thus enhancing the efficiency of data processing. Linear graphic simplification has been taken into account in the process of displacement by transferring the linear graphic simplification into displacement of points on the line, constructing propagation paths between proximal map objects and considering spatial context and map perception rules. At the same time, the spatial characteristics of map objects are maintained as far as possible. Also, the roads and their surrounding buildings as an example are handled by means of this method, and effectiveness and availability of this method is verified.

A Mixed Land Cover Spatio-temporal Data Model Based on Object-oriented and Snapshot

LI Yinchao, LI Jiansong

2016, 45(7):  858-865.  doi:10.11947/j.AGCS.2016.20150176

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Spatio-temporal data model (STDM) is one of the hot topics in the domains of spatio-temporal database and data analysis. There is a common view that a universal STDM is always of high complexity due to the various situation of spatio-temporal data. In this article, a mixed STDM is proposed based on object-oriented and snapshot models for modelling and analyzing landcover change (LCC). This model uses the object-oriented STDM to describe the spatio-temporal processes of land cover patches and organize their spatial and attributive properties. In the meantime, it uses the snapshot STDM to present the spatio-temporal distribution of LCC on the whole via snapshot images. The two types of models are spatially and temporally combined into a mixed version. In addition to presenting the spatio-temporal events themselves, this model could express the transformation events between different classes of spatio-temporal objects. It can be used to create database for historical data of LCC, do spatio-temporal statistics, simulation and data mining with the data. In this article, the LCC data in Heilongjiang province is used for case study to validate spatio-temporal data management and analysis abilities of mixed STDM, including creating database, spatio-temporal query, global evolution analysis and patches spatio-temporal process expression.

A Method of Urban Traffic Flow Speed Estimation Using Sparse Floating Car Data

WANG Xiaomeng, PENG Ling, CHI Tianhe

2016, 45(7):  866-873.  doi:10.11947/j.AGCS.2016.20150472

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The sample spatio-temporalsparsity is one of the major challenges for traffic estimation when using floating car data (FCD).Spatio-temporal characteristics of road traffic flow are analysed and applied to build a naive Bayes-based traffic estimation model which is proposed to estimate the missing traffic state of the roads which are not covered by samples. In the model, the adjacent period traffic flow speed of the target road segment is considered for the representation of the time characteristic. And instead of Euclidean distance and topology relationship, urban traffic flow similarity relationships are mined to quantify the interior space features of urban traffic.The result demonstrates that the method is effective for missing traffic state estimation and more precision compared to traditional methods based on topology relationship.As a conclusion, the proposed model can solve the spatio-temporal sparsity problem effectively, which has a strong practical significance for traffic application based on FCD.

A Simplification of Residential Feature by the Shape Cognition and Template Matching Method

YAN Xiongfeng, AI Tinghua, YANG Min

2016, 45(7):  874-882.  doi:10.11947/j.AGCS.2016.20150162

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Aiming at the typical template characteristics of building representation, this study built a series of templates to abstract the building shape by generalizing building polygons and analyzing the typical characteristics of regional environment.The shape description operator used the turn function method through the measure of the similarity between the building target and the template. From the perspective of shape cognition, this method conducted the building simplification by searching and matching the most similar template to replace the target building. The presented method is able to guarantee the overall shape structure unchanging and maintaining the area balance after the simplification. The experiments under real data show that the method holds high reliability and practicability, able to be widely applied to practical map generalization.