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A landscape shape index-based sampling approach for land cover accuracy assessment

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Science China Earth Sciences 2016年第12期59卷 2263-2274页

作者： CHEN Fei CHEN Jun WU Hao HOU DongYang ZHANG WeiWei ZHANG Jun ZHOU XiaoGuang CHEN LiJun School of Geosciences and Info-Physics Central South University National geomatics center of China

Spatial sampling design is one of the key steps in land cover accuracy assessment,and many traditional sampling approaches may not achieve credible spatial sampling due to the high spatial heterogeneity of land *** paper characterizes the spatial heterogeneity with three-level LSIs and determines the subsequent sample sizes and their spatial *** three-level LSIs are rLSI in a region,cLSI for each land cover class and uLSI in each geographic sampling unit in the *** rLSIs are used to derive appropriate sample sizes in the target *** cLSIs are used to assure that larger sample numbers are allocated to land cover classes with higher spatial *** uLSIs provide useful measures for selecting optimal geographic units in which sample sites will be *** LSI-based sampling approach can derive the sample sizes and determine their distributions in an adaptive way according to the spatial *** experimental case study further demonstrates that the LSI-based sampling approach obtains more appropriate sample sizes for each region,sufficient sample numbers for rare classes,and optimal sample distributions in the geographical space.

关键词： Land cover Sampling Landscape index Spatial heterogeneity Accuracy assessment

Global cultivated land mapping at 30 m spatial resolution

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Science China Earth Sciences 2016年第12期59卷 2275-2284页

作者： CAO Xin CHEN XueHong ZHANG WeiWei LIAO AnPing CHEN LiJun CHEN ZhiGang CHEN Jin State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University National geomatics center of China College of geomatics Anhui University of Science and Technology

Cultivated land is one of the most important types of land cover in the global mapping of land cover, and its variation influences economic development, food security, and ecological environment protection. Existing products of global cultivated land mapping have a low resolution, and high spatial resolution products are in demand. This study uses global remote sensing image datasets in 2000/2010 with a spatial resolution of 30 m(Landsat TM/ETM+, HJ-1), MODIS 250 m NDVI time-serial data, and many types of reference data. An three-layer extraction method based on pixels, objects, and knowledge(POK) was adopted to ease cultivated land extraction in global-scale 30 m images, i.e., cultivated land classification based on pixel-scale multi-feature optimization, cultivated land automatic identification based on objects, and interactive object processing based on information service and priori knowledge. Global 30 m cultivated land mapping was accomplished for the two reference years(2000 and 2010), and statistical analysis was conducted on the data. Results showed that the total cultivated land area was 1.903 billion ha and 1.960 billion ha, respectively. Accuracy assessments showed that overall accuracy of global cultivated land mapping are higher than 92% for both the two reference years. The global cultivated land products in 2000/2010 developed in this research are superior to their international counterparts in terms of spatial resolution and classification accuracy. They also provide significant basic data on global food security, ecological environment supervision, and global change.

关键词： Cultivated land global 30 m resolution Remote sensing mapping NDVI time series

Geometric-constrained multi-view image matching method based on semi-global optimization

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Geo-Spatial Information Science 2018年第2期21卷 115-126页

作者： Wenhao Zhao Li Yan Yunsheng Zhang School of Geodesy and geomatics Wuhan UniversityWuhanChina National geomatics center of China BeijingChina School of Geosciences and Info-Physics Central South UniversityChangshaChina

Targeting at a reliable image matching of multiple remote sensing images for the generation of digital surface models,this paper presents a geometric-constrained multi-view image matching method,based on an energy minimization *** employing a geometrical constraint,the cost value of the energy function was calculated from multiple images,and the cost value was aggregated in an image space using a semi-global optimization approach.A homography transform parameter calculation method is proposed for fast calculation of projection pixel on each image when calculation cost *** is based on the known interior orientation parameters,exterior orientation parameters,and a given elevation *** an efficient and reliable processing of multiple remote sensing images,the proposed matching method was performed via a coarse-to-fine strategy through image *** sets of airborne remote sensing images were used to evaluate the performance of the proposed *** reveal that the multi-view image matching can improve matching ***,the experimental results show that the proposed method performs better than traditional methods.

关键词： Image matching multiview images semi-global optimization digital surface model(DSM)

Event-based incremental updating of spatio-temporal database

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Journal of Central South University of Technology 2004年第2期11卷 192-198页

作者：周晓光陈军蒋捷朱建军李志林 College of Info-Physics and geomatics Engineering Central South University National geomatics center of China Department of Land Surveying and Geo-Informatics Hong Kong Polytechnic University

Based on the relationship among the geographic events, spatial changes and the database operations, a new automatic (semi-automatic) incremental updating approach of spatio-temporal database (STDB) named as (event-based) incremental updating (E-BIU) is proposed in this paper. At first, the relationship among the events, spatial changes and the database operations is analyzed, then a total architecture of E-BIU implementation is designed, which includes an event queue, three managers and two sets of rules, each component is presented in detail. The process of the E-BIU of master STDB is described successively. An example of building’s incremental updating is given to illustrate this approach at the end. The result shows that E-BIU is an efficient automatic updating approach for master STDB.

关键词： incremental updating geographic event spatial change database operation manager

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Analyzing the effect of earthquakes on OpenStreetMap contribution patterns and tweeting activities

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Geo-Spatial Information Science 2018年第3期21卷 195-212页

作者： Ahmed Ahmouda Hartwig H.Hochmair Sreten Cvetojevic geomatics Program Fort Lauderdale Research and Education CenterUniversity of FloridaFloridaFort LauderdaleUSA

Natural disasters,such as wildfires,earthquakes,landslides,or floods,lead to an increase in topical information shared on social media and in increased mapping activities in volunteered geographic information(VGI)*** earthquakes in Nepal and Central Italy as case studies,this research analyzes the effects of natural disasters on short-term(weeks)and longer-term(half year)changes in OpenStreetMap(OSM)mapping behavior and tweet activities in the affected *** increase of activities in OSM during the events can be partially attributed to those focused OSM mapping campaigns,for example,through the Humanitarian OSM Team(HOT).Using source tags in OSM change-sets,it was found that only a small portion of external mappers actually travels to the affected regions,whereas the majority of external mappers relies on desktop mapping ***,the study analyzes the spatio-temporal sequence of posted tweets together with keyword filters to identify a subset of users who most likely traveled to the affected regions for support and rescue *** also explores where,geographically,earthquake information spreads within social networks.

关键词： Volunteered geographic information(VGI) OpenStreetMap(OSM) Twitter natural disaster human dynamics

Inversion of surface vegetation water content based on GNSS-IR and MODIS data fusion

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Satellite Navigation 2020年第1期1卷 230-244页

作者： Yalong Pan Chao Ren Yueji Liang Zhigang Zhang Yajie Shi College of geomatics and Geoinformation Guilin University of TechnologyGuilin 541006China Research center of Precise Engineering Surveying Guangxi Key Laboratory of Spatial Information and GeomaticsGuilin 541006China

Obtaining high-precision,long-term sequences of vegetation water content(VWC)is of great significance for assessing surface vegetation growth,soil moisture,and fire *** recent years,the global navigation satellite system-interferometric reflection(GNSS-IR)has become a new type of remote sensing technology with low cost,all-weather capability,and a high temporal *** has been widely used in the fields of snow depth,sea level,soil moisture content,and vegetation water *** normalized microwave reflectance index(NMRI)based on GNSS-IR technology has been proven to be effective in monitoring changes in *** paper considers the advantages and disadvantages of remote sensing technology and GNSS-IR technology in estimating VWC.A point-surface fusion method of GNSS-IR and MODIS data based on the GA-BP neural network is proposed to improve the accuracy of VWC *** vegetation index products(NDVI,GPP,LAI)and the NMRI that unified the temporal and spatial resolution were used as the input and output data of the training model,and the GA-BP neural network was used for training and ***,a spatially continuous NMRI product was *** a particular area of the United States as a research object,experiments show that(1)a neural network can realize the effective fusion of GNSS-IR and MODIS *** comparing the GA-BP neural network,BP neural network,and multiple linear regression(MLR),the three models fusion *** results show that the GA-BP neural network has the best modeling effect,and the r and RMSE between the model estimation result and the reference value are 0.778 and 0.0332,respectively;this network is followed by the BP neural network,in which the r and RMSE are 0.746 and 0.0465,*** has the poorest effect,with r and RMSE values of 0.500 and 0.0516,respectively.(2)The spatiotem-poral variation in the 16 days/500 m resolution NMRI product obtained by GA-BP neural network fusion is consistent with that

关键词： Vegetation water content GNSS-IR MODIS GA-BP Fusion Precision analysis

IMPROVING 9-INTERSECTION MODEL BY REPLACING THE COMPLEMENT WITH VORONOI REGION

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Geo-Spatial Information Science 2000年第1期3卷 1-10页

作者： CHEN Jun LI Chengming LI Zhilin Gold C M National geomatics Center of China Beijling China

9-intersection model is the most popular framework used for formalizing the spatial relations between two spatial objectsA andB. It transforms the topological relationships between two simple spatial objectsA andB into point-set topology problem in terms of the intersections ofA’s boundary (?A), interior (A 0) and (A ?) withB’s boundary (?B), interior (B 0) and exterior (B ?). It is shown in this paper that there exist some limitations of the original 9-intersection model due to its definition of an object’s exterior as its complement, and it is difficult to distinguish different disjoint relations and relations between complex objects with holes, difficult or even impossible to compute the intersections with the two object’s complements (?A∩B ?,A 0∩?B ?,A ?∩?B,A ?∩B 0 andA ?∩B ?)since the complements are infinitive. The authors suggest to re-define the exterior of spatial object by replacing the complement with its Voronoi region. A new Voronoi-based 9-intersection (VNI) is proposed and used for formalizing topological relations between spatial bojects. By improving the 9-intersection model, it is now possible to distinguish disjoint relations and to deal with objects with holes. Also it is possible to compute the exterior-based intersections and manipulate spatial relations with the VNI.

关键词： 9-intersection model Voronoi region topological relationship

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Variability features of the width of the tropical belt from COSMIC radio occultation data

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Science China Earth Sciences 2016年第4期59卷 795-802页

作者： GAO Pan ZHANG XiaoHong XU XiaoHua School of Geodesy and geomatics Wuhan University Wuhan 430079 China Collaborative Innovation center for Geospatial Technology Wuhan 430079 China

In this work, we analyzed time-series and trends of the tropical belt edges and widths with three methods based on the tropopause using new global positioning system radio occultation(GPS RO) data from the Constellation Observing System for Meteorology, Ionosphere, and Climate(COSMIC) mission for September 2006–February 2014. The results from the three methods agreed well with previous studies and new features were found. To avoid the El Ni?o Southern Oscillation(ENSO) and Quasi-Biennial Oscillation(QBO) influence, we applied a simple multiple linear regression model to the monthly anomalies to obtain the tropical belt edges and width trends. During the study, we found equatorward movements of the tropical belt edges on both hemispheres. The narrowing of the tropical belt mainly occurred in the Pacific Ocean. We also found that the deseasonalized monthly anomalies of the tropical belt width were closely related with the ENSO and QBO. The tropical belt at a height of 15 km was mostly closely related with the ENSO. The correlations between the QBO and the tropical belt were consistent for the three methods.

关键词： COSMIC GPS Radio Occultation Tropical belt width Tropopause

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Exploring the applications of 3D proximity analysis in a 3D digital cadastre

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Geo-Spatial Information Science 2021年第2期24卷 201-214,I0002页

作者： Saeid Emamgholian Mohammad Taleai Davood Shojaei Faculty of Geodesy and geomatics Engineering K.N.Toosi University of TechnologyTehranIran geomatics Department Laval UniversityQuebecCanada center for SDIs and Land Administration Department of Infrastructure EngineeringThe University of MelbourneMelbourneAustralia

Increasing population in urban areas and limitations of suitable lands for developing houses and urban infrastructure have led to the vertical development in ***,these developments are managed by a cadastral system which is mainly two-dimensional and cannot efficiently represent Rights,Restrictions,and Responsibilities(RRRs)in complex *** fact,a three-dimensional cadastre is required for efficiently registering and representing *** this paper,a 3D proximity analysis was proposed and implemented to determine RRRs and associated easement rights in non-topology-based data *** method can be used to investigate the surrounding spaces of a subject apartment unit or storage in a *** performance of the developed method was evaluated in a large complex high-rise in Tehran,*** results confirmed that the proposed method can correctly identify the neighbor spaces in complex scenarios.

关键词： 3D visualization 3D cadastre easements proximity analysis GIS