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An IconMap-based exploratory analytical approach for multivariate geospatial data

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Science China(Information Sciences) 2013年第1期56卷 198-207页

作者： ZHANG XianFeng liAO ChunHua liU Yu li jonathan Institute of Remote Sensing and GIS Peking University Department of Geography and Environmental Management University of Waterloo

This paper discusses an iconmap-based visualization technique that enables multiple geospatial variables to be illustrated in a single GIS raster *** is achieved by extending the conventional pixelbased data structure to an iconic *** this way,spatial patterns generated by the interaction of geographic variables can be disclosed,and geospatial information mining can be readily *** a case study,a visual analysis of soil organic matter and soil nutrients for Shuangliu County in the city of Chengdu,China,was undertaken using the prototype IconMapper software,developed by the *** results show that the static IconMap can accurately exhibit trends in the distribution of organic matter and nutrients in *** dynamic iconmap can both reflect interaction patterns between organic matter and the nutrient variables,and display soil fertility levels in a comprehensive ***,the iconmap-based visualization approach is shown to be a non-fused,exploratory analytical approach for multivariate data analysis and as a result is a valuable method for visually analyzing soil fertility conditions.

关键词： iconmap soil fertility visualization icon blocks multivariate geospatial data

Spatio-temporal patterns of satellite-derived grassland vegetation phenology from 1998 to 2012 in Inner Mongolia, China

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Journal of Arid Land 2016年第3期8卷 462-477页

作者： SHA Zongyao ZHONG Jialin BAI Yongfei TAN Xicheng jonathan li International Software School Wuhan University Department of Geography & Environmental Management University of Waterloo Institute of Botany Chinese Academy of Sciences

Spatio-temporal variations of vegetation phenology, e.g. start of green-up season（SOS） and end of vegetation season（EOS）, serve as important indicators of ecosystems. Routinely processed products from remotely sensed imagery, such as the normalized difference vegetation index（NDVI）, can be used to map such variations. A remote sensing approach to tracing vegetation phenology was demonstrated here in application to the Inner Mongolia grassland, China. SOS and EOS mapping at regional and vegetation type（meadow steppe, typical steppe, desert steppe and steppe desert） levels using SPOT-VGT NDVI series allows new insights into the grassland ecosystem. The spatial and temporal variability of SOS and EOS during 1998–2012 was highlighted and presented, as were SOS and EOS responses to the monthly climatic fluctuations. Results indicated that SOS and EOS did not exhibit consistent shifts at either regional or vegetation type level; the one exception was the steppe desert, the least productive vegetation cover, which exhibited a progressive earlier SOS and later EOS. Monthly average temperature and precipitation in preseason（February, March and April） imposed most remarkable and negative effects on SOS（except for the non-significant impact of precipitation on that of the meadow steppe）, while the climate impact on EOS was found to vary considerably between the vegetation types. Results showed that the spatio-temporal variability of the vegetation phenology of the meadow steppe, typical steppe and desert steppe could be reflected by the monthly thermal and hydrological factors but the progressive earlier SOS and later EOS of the highly degraded steppe desert might be accounted for by non-climate factors only, suggesting that the vegetation growing period in the highly degraded areas of the grassland could be extended possibly by human interventions.

关键词： phenological timing degradation harmonic analysis human activity climate restoration

Web-based visualization of large 3D urban building models

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International Journal of Digital Earth 2014年第1期7卷 53-67页

作者： liqiang Zhang Chunming Han liang Zhang Xiaokun Zhang jonathan li State Key Laboratory of Remote Sensing Science Beijing Normal UniversityBeijingChina The Center for Earth Observation and Digital Earth Chinese Academy of ScienceBeijingChina Department of Computer Science Beijing Electronic Science and Technology InstituteBeijingChina Department of Geography and Environmental Management Faculty of EnvironmentUniversity of WaterlooWaterlooCanada

Adaptive rendering of large urban building models has become an important research issue in three-dimensional(3D)geographic information system(GIS)*** study explores a way for rendering web-based 3D urban building models.A client-server hybrid rendering approach is presented for large 3D city models,stored on a remote server through a *** approach combines an efficient multi-hierarchical building representation with a novel image-based method,3D image impostor generated on demand by a remote *** approach allows transferring complex scenes progressively while keeping high visualization *** also evaluated the rendering and data transferring performance of the proposed approach.

关键词： urban building models progressive transmission client-server hybrid 3D visualization

GIS-based spatial prediction of landslide using road factors and random forest for Sichuan-Tibet Highway

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Journal of Mountain Science 2022年第2期19卷 461-476页

作者： YE Cheng-ming WEI Rui-long GE Yong-gang li Yao Jose Marcato JUNIOR jonathan li Key Laboratory of Earth Exploration and Information Technology of Ministry of Education Chengdu University of TechnologyChengdu 610059China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China Faculty of Engineering Architecture and Urbanism and GeographyFederal University of Mato Grosso do SulCampo Grande 79070-900Brazil Department of Geography and Environmental Management University of WaterlooWaterlooONN2L 3G1Canada

Accurate evaluation of landslide susceptibility is very important to ensure the safe operation of mountain *** Sichuan-Tibet Highway,which traverses the east of the Tibetan Plateau,frequently encounters natural *** studies generally use statistical methods to analyze the hazards along the Sichuan-Tibet *** this research,we present two road factors,namely aspect to road and road profile to increase the accuracy of landslide susceptibility mapping by considering the influence of landslide movement direction on ***,the aspect to road,which represents the impact of different landslide movement directions on the highway,was extracted by combining road direction with mountain ***,the road profile,which reflects the subgrade structure between the road and surrounding mountains,was extracted according to the terrain ***,the landslide susceptibility maps were produced based on the random forest(RF)method by using 473 landslides and 10 conditioning factors,including road factors(aspect to road,road profile)and primitive factors(slope,aspect,curvature,relief amplitude,peak ground acceleration,crustal movement velocity,faults,rainfall).The area under the receiver operating characteristic curve(AUC)and the Gini importance were used to evaluate the performance of proposed road *** AUC values on two groups that add road factors and only use primitive factors were 0.8517 and 0.8243,*** Gini importance indicated that road profile(0.123)and aspect to road(0.116)have a significant contribution to landslides compared with the primitive *** results of multi-collinearity analysis and frequency ratio confirmed the suitability of the road factors for predicting hazards along the highway.

关键词： Landslide susceptibility Spatial modeling Random forest Sichuan-Tibet Highway

Formula for calculating spatial similarity degrees between point clouds on multi-scale maps taking map scale change as the only independent variable

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Geodesy and Geodynamics 2015年第2期6卷 113-125页

作者： Yang Weifang Yan Haowen li jonathan Department of GIS Lanzhou Jiaotong University Department of Geography & Environmental Management University of Waterloo Gansu Provincial Engineering Laboratory for National Geographic State Monitoring

The degree of spatial similarity plays an important role in map generalization, yet there has been no quantitative research into it. To fill this gap, this study first defines map scale change and spatial similarity degree/relation in multi-scale map spaces and then proposes a model for calculating the degree of spatial similarity between a point cloud at one scale and its gener- alized counterpart at another scale. After validation, the new model features 16 points with map scale change as the x coordinate and the degree of spatial similarity as the y coordinate. Finally, using an application for curve fitting, the model achieves an empirical formula that can calculate the degree of spatial similarity using map scale change as the sole independent variable, and vice versa. This formula can be used to automate algorithms for point feature generalization and to determine when to terminate them during the generalization.

关键词： Spatial similarity degree Map generalization Map scale change Point clouds Quantitative description Spatial similarity relations Multi-scale map spaces Curve fitting method

Assessing the impacts of human activities and climate variations on grassland productivity by partial least squares structural equation modeling(PLS-SEM)

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Journal of Arid Land 2017年第4期9卷 473-488页

作者： SHA Zongyao XIE Yichun TAN Xicheng BAI Yongfei li jonathan liU Xuefeng International Software School Wuhan University Department of Geography and Geology Eastern Michigan University Institute of Botany Chinese Academy of Sciences Department of Geography & Environmental Management University of Waterloo School of Communication and Information Engineering Shanghai University

The cause-effect associations between geographical phenomena are an important focus in ecological research. Recent studies in structural equation modeling（SEM） demonstrated the potential for analyzing such associations. We applied the variance-based partial least squares SEM（PLS-SEM） and geographically-weighted regression（GWR） modeling to assess the human-climate impact on grassland productivity represented by above-ground biomass（AGB）. The human and climate factors and their interaction were taken to explain the AGB variance by a PLS-SEM developed for the grassland ecosystem in Inner Mongolia, China. Results indicated that 65.5% of the AGB variance could be explained by the human and climate factors and their interaction. The case study showed that the human and climate factors imposed a significant and negative impact on the AGB and that their interaction alleviated to some extent the threat from the intensified human-climate pressure. The alleviation may be attributable to vegetation adaptation to high human-climate stresses, to human adaptation to climate conditions or/and to recent vegetation restoration programs in the highly degraded areas. Furthermore, the AGB response to the human and climate factors modeled by GWR exhibited significant spatial variations. This study demonstrated that the combination of PLS-SEM and GWR model is feasible to investigate the cause-effect relation in socio-ecological systems.

关键词： spatial modeling human-natural interaction grazing urbanization road network

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利用多源遥感数据改进地面太阳直射辐射估算

太阳能学报 2014年第8期35卷 1473-1479页

作者：张显峰刘羽 jonathan li 吕扬北京大学遥感与地理信息系统研究所北京100871 加拿大滑铁卢大学地理与环境管理学院

通过夏冬两季不同时间分辨率的气溶胶和大气可降水数据对太阳直射辐射估算进行敏感性分析,结果表明,气溶胶产品对太阳辐射估算结果的敏感性更高。融合MODIS与FY-3A的两种气溶胶产品来优化新疆地区气溶胶数据,尤其是高反射的沙漠与戈壁... 详细信息

通过夏冬两季不同时间分辨率的气溶胶和大气可降水数据对太阳直射辐射估算进行敏感性分析,结果表明,气溶胶产品对太阳辐射估算结果的敏感性更高。融合MODIS与FY-3A的两种气溶胶产品来优化新疆地区气溶胶数据,尤其是高反射的沙漠与戈壁地区的气溶胶信息得到较大改善;同时通过引入FY-2D云类型数据更好地刻画了不同类型云层对太阳辐射估算精度的影响,以便更准确地估算新疆地区的地面太阳直射辐射。以喀什和乌鲁木齐站的观测值为参照,验证结果表明优化后的估算比优化前精度有明显提高。

关键词：太阳能潜力风云卫星敏感性分析气溶胶云类型

GiT-based structural geologic feature analysis of the southern segment of Longmenshan fault zone for earthquake evidence

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Journal of Mountain Science 2016年第5期13卷 906-916页

作者： YE Cheng-ming CUI Peng Saied PIRASTEH jonathan li MENG Qingkai BI Xiao-jia ZHANG Jian-qiang Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China Key Lab.of Earth Exploration and Information Technology of Ministry of Education Chengdu University of TechnologyChengdu 610059China Department of Geography and Environmental Management Faculty of EnvironmentUniversity of WaterlooWaterlooOntarioCanada N2L 3G1Canada Chengdu Earthquake Mitigation Bureau Chengdu 610042China

The Longmenshan fault is a thrust fault which runs along the base of the Longmen Mountains in Siehuan province, southwestern China. The southern segment of the fault had two distinct responses to the Ms 8 Wenehuan and Ms 7 Lushan earthquakes. This study determines characteristics of the structural geology of the Longmenshan fault to evaluate how it influenced the two aforementioned earthquakes. This research was done within a Geo- information Technologies （GiT） environment based on multi-source remote sensing and crustal movement data extracted from the Global Positioning System （GPS）. The spatial distribution of the southern segment of the Longmenshan fault zone was comprehensively analyzed to study both earthquakes. The study revealed that the Wenehuan and Lushan earthquakes occurred on two relatively independent faults. In addition, there was a nearly constant-velocity crustal movement zone between the two epicenters that probably had a compressive stress with slow motion. Furthermore, the central fault and a mountain back fault gradually merged from north to south. The Lushan earthquake of the Wenchuan earthquake. was not an affershock The research showed that fault zones within 30-50 km of State Highway 318 are intensive and complex. In addition, crustal movement velocity decreased rapidly, with a strong multi-directional shear zone. Thus, activity in that zone was likely stronger than in the northern part over the medium to long term.

关键词： Longmenshan fault zone Geoinformation Technologies (GiT) Remote Sensing (RS) Earthquake Crustal movement

基于高光谱遥感影像的建筑物表面材质识别方法（英文）

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2017年第12期18卷 984-990页

作者： Cheng-ming YE Peng CUI Saied PIRASTEH jonathan li Yao li Key Laboratory of Earth Exploration and Information Technology of Ministry of Education Chengdu University of TechnologyChengdu 610059China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China Department of Geography and Environmental Management Faculty of EnvironmentUniversity of WaterlooWaterloo N2L 3G1Canada

目的:建筑物的材质信息是灾害评估和城市调查等领域的重要信息。本文旨在利用高光谱遥感影像提取地面建筑物的表面材质信息(包括材质类型和主要组成成份),并对提取方法进行对比,给出应用建议。创新点:对建筑物材料进行光谱测试,并对其... 详细信息

目的:建筑物的材质信息是灾害评估和城市调查等领域的重要信息。本文旨在利用高光谱遥感影像提取地面建筑物的表面材质信息(包括材质类型和主要组成成份),并对提取方法进行对比,给出应用建议。创新点:对建筑物材料进行光谱测试,并对其高光谱响应规律进行分析,找出有诊断意义的光谱位置;基于实验和验证得出应用方法的适应性,以提高信息提取精度。方法:1.设计建筑物材质信息提取流程(图1),并对高光谱数据进行基础处理;2.对建筑物材料进行光谱测试(波长范围为350~2500 nm,图3),并完成各类建筑物的诊断性光谱分析;3.利用光谱角度法(公式(1))和光谱信息散度法(公式(2))进行材质信息提取(图5和6);4.综合分析两种方法的应用过程与控制参数和准确率的关系。结论:1.两种方法皆可提取建筑物材质信息,但在应用过程中需要进行参数的适应性调整,这是提高准确率的关键;2.在建筑物材质信息提取方面,光谱角度法的提取准确率略高于光谱散度法。

关键词：建筑物材料高光谱遥感光谱分析光谱识别