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Prof. Jiangfeng She
School of Geography and Ocean Science, Nanjing University

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0 geographic information system
0 virtual geographic environment
0 spatiotemporal data model
0 geographic database

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Journal article
Published: 20 June 2021 in ISPRS International Journal of Geo-Information
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Simplification of 3D building models is an important way to improve rendering efficiency. When existing algorithms are directly applied to simplify multi-component models, generally composed of independent components with strong topological dependence, each component is simplified independently. The consequent destruction of topological dependence can cause unreasonable separation of components and even result in inconsistent conclusions of spatial analysis among different levels of details (LODs). To solve these problems, a novel simplification method, which considers the topological dependence among components as constraints, is proposed. The vertices of building models are divided into boundary vertices, hole vertices, and other ordinary vertices. For the boundary vertex, the angle between the edge and component (E–C angle), denoting the degree of component separation, is introduced to derive an error metric to limit the collapse of the edge located at adjacent areas of neighboring components. An improvement to the quadratic error metric (QEM) algorithm was developed for the hole vertex to address the unexpected error caused by the QEM’s defect. A series of experiments confirmed that the proposed method could effectively maintain the overall appearance features of building models. Compared with the traditional method, the consistency of visibility analysis among different LODs is much better.

ACS Style

Biao Wang; Guoping Wu; Qiang Zhao; Yaozhu Li; Yiyuan Gao; Jiangfeng She. A Topology-Preserving Simplification Method for 3D Building Models. ISPRS International Journal of Geo-Information 2021, 10, 422 .

AMA Style

Biao Wang, Guoping Wu, Qiang Zhao, Yaozhu Li, Yiyuan Gao, Jiangfeng She. A Topology-Preserving Simplification Method for 3D Building Models. ISPRS International Journal of Geo-Information. 2021; 10 (6):422.

Chicago/Turabian Style

Biao Wang; Guoping Wu; Qiang Zhao; Yaozhu Li; Yiyuan Gao; Jiangfeng She. 2021. "A Topology-Preserving Simplification Method for 3D Building Models." ISPRS International Journal of Geo-Information 10, no. 6: 422.

Journal article
Published: 06 May 2021 in ISPRS International Journal of Geo-Information
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Progressive encoding and transmission, i.e., a crucial technical foundation of 3D Web Geographic Information Systems (WebGIS), addresses the contradiction between massive 3D building data and limited network transmission capacity. Most progressive encoding algorithms, taking vertices, edges or triangles as encoding units, may break the inherent geometric and topological characteristics of 3D building models. Thus, a novel 3D building model encoding method that can maintain the internal characteristics is proposed, which can be used for high-efficiency progressive transmission. With this method, each building is decomposed into three types of fundamental structures: main structure, independent structure and attached structure. A structural topology graph (STG) was constructed based on the connections among structures. Guided by STG, one or more structures were wrapped as the smallest incremental transmission unit, denoted as transmission node. When requested, the real-time position of viewpoint, orientation and visual importance of nodes are used to pick up expected nodes for responding. The results confirm that the proposed method can better maintain the geometric and topological characteristics while encoding 3D building models. While serving for transmission, the proposed method not only effectively reduces the transmission load, but also provides users with a better consistency experience on the building appearance at different simplification levels.

ACS Style

Jiwei Dong; Junzhong Tan; Qiang Zhao; Lixia He; Sirui Li; Jiangfeng She. Structure-Level 3D Building Model Encoding Method for Progressive Transmission. ISPRS International Journal of Geo-Information 2021, 10, 306 .

AMA Style

Jiwei Dong, Junzhong Tan, Qiang Zhao, Lixia He, Sirui Li, Jiangfeng She. Structure-Level 3D Building Model Encoding Method for Progressive Transmission. ISPRS International Journal of Geo-Information. 2021; 10 (5):306.

Chicago/Turabian Style

Jiwei Dong; Junzhong Tan; Qiang Zhao; Lixia He; Sirui Li; Jiangfeng She. 2021. "Structure-Level 3D Building Model Encoding Method for Progressive Transmission." ISPRS International Journal of Geo-Information 10, no. 5: 306.

Journal article
Published: 06 April 2021 in ISPRS International Journal of Geo-Information
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Complex 3D building models, because of their huge data volume, almost always result in transmission congestion, which leads to poor user experience. To reduce the real-time transmission pressure, a novel view-dependent progressive transmission method was developed. With this method, only a small amount of transmitted data is necessary to achieve an acceptable rendering effect when the viewpoint changes. The method involves two stages. A preprocessing stage simplifies the building model using a multi-level vertex clustering algorithm. The local mesh in each clustering unit is organized into a node tree where each node includes a vertex and its related triangles. The building model is finally reorganized into a node forest. In the reconstruction stage, all root nodes are transmitted first to build a basic model. Their descendant nodes are then requested and transmitted according to viewpoint information to refine the building model during user interaction. The experimental results show that this method can effectively improve the transmission and reconstruction efficiency of 3D building models.

ACS Style

Yuchang Sun; Jingsong Ma; Jiangfeng She; Qiang Zhao; Lixia He. View-Dependent Progressive Transmission Method for 3D Building Models. ISPRS International Journal of Geo-Information 2021, 10, 228 .

AMA Style

Yuchang Sun, Jingsong Ma, Jiangfeng She, Qiang Zhao, Lixia He. View-Dependent Progressive Transmission Method for 3D Building Models. ISPRS International Journal of Geo-Information. 2021; 10 (4):228.

Chicago/Turabian Style

Yuchang Sun; Jingsong Ma; Jiangfeng She; Qiang Zhao; Lixia He. 2021. "View-Dependent Progressive Transmission Method for 3D Building Models." ISPRS International Journal of Geo-Information 10, no. 4: 228.

Journal article
Published: 17 December 2020 in Forests
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Street greenery plays an essential role in improving the street environment and residents’ health. The evaluation of street greenery is of great value to establish environmentally friendly streets. The evaluation indicators of present studies evaluating street greenery were relatively single, either the Green View Index (GVI) or Normalized Difference Vegetation Index (NDVI), which cannot describe the greenery condition in its entirety. The objective of this study is to assess the street greenery using multiple indicators, including GVI, NDVI, and Vegetation Structural Diversity (VSD). We combined street view images with a semantic segmentation method to extract the GVI and VSD and used satellite images to calculate the NDVI in the urban area of Nanjing, China. We found correlations and discrepancies of these indicators using statistical analyses in different urban districts, functional areas, and road levels. The results indicate that: (1) the GVI and NDVI are strongly correlated in open spaces, whereas weakly correlated in residential and industrial lands, (2) the areas with higher VSD are mainly located in the new city, whereas the VSD in the old city is lower, and a weak negative correlation exists between the GVI and VSD in the research area, and (3) the old city has a higher GVI level compared to the new city on the main road, whereas the new city has a higher GVI level than the old city on the branch road. Compared with the GVI, the trend of VSD in the old city and the new city is relatively consistent. Our findings suggest that considering multiple indicators of street greenery evaluation can provide a comprehensive reference for building more human-friendly and diversified street green belts.

ACS Style

Ming Tong; Jiangfeng She; Junzhong Tan; Mengyao Li; Rongcun Ge; Yiyuan Gao. Evaluating Street Greenery by Multiple Indicators Using Street-Level Imagery and Satellite Images: A Case Study in Nanjing, China. Forests 2020, 11, 1347 .

AMA Style

Ming Tong, Jiangfeng She, Junzhong Tan, Mengyao Li, Rongcun Ge, Yiyuan Gao. Evaluating Street Greenery by Multiple Indicators Using Street-Level Imagery and Satellite Images: A Case Study in Nanjing, China. Forests. 2020; 11 (12):1347.

Chicago/Turabian Style

Ming Tong; Jiangfeng She; Junzhong Tan; Mengyao Li; Rongcun Ge; Yiyuan Gao. 2020. "Evaluating Street Greenery by Multiple Indicators Using Street-Level Imagery and Satellite Images: A Case Study in Nanjing, China." Forests 11, no. 12: 1347.

Articles
Published: 06 July 2020 in Cartography and Geographic Information Science
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Many studies have been focused on rendering 2D vector elements on 3D terrain, and a series of algorithms have been proposed. Most of these algorithms struggle to provide a seamless overlay between vector elements and an irregular terrain surface. Despite their importance, the physical characteristics of vector elements are often ignored, which distorts the surface of vector elements. For example, if vector elements that represent roads and rivers are simply overlaid on terrain, the phenomena of uneven surfaces and rivers going uphill may occur because of elevation fluctuation. To correct these deficiencies, terrain should be modified according to the physical characteristics of vectors. We propose a local terrain modification method: First, the elevation of terrain covered by vector elements is recalculated according to vectors’ physical characteristics. Second, the multigrid method is used to realize a smooth transition between the modified terrain and its surrounding area. Finally, by setting different transition ranges and comparing the visualization effects, rules are given for the selection of a suitable range. After modification, the terrain conforms to vectors’ physical characteristics, and the overall relief is undamaged. The proposed method was applied to a CPU–GPU parallel heterogeneous model and demonstrated a high level of performance.

ACS Style

Jiangfeng She; Junyan Liu; Junzhong Tan; Jiwei Dong; Wang Biao. Local terrain modification method considering physical feature constraints for vector elements. Cartography and Geographic Information Science 2020, 47, 452 -470.

AMA Style

Jiangfeng She, Junyan Liu, Junzhong Tan, Jiwei Dong, Wang Biao. Local terrain modification method considering physical feature constraints for vector elements. Cartography and Geographic Information Science. 2020; 47 (5):452-470.

Chicago/Turabian Style

Jiangfeng She; Junyan Liu; Junzhong Tan; Jiwei Dong; Wang Biao. 2020. "Local terrain modification method considering physical feature constraints for vector elements." Cartography and Geographic Information Science 47, no. 5: 452-470.

Journal article
Published: 27 May 2020 in ISPRS International Journal of Geo-Information
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Cost distance is one of the fundamental functions in geographical information systems (GISs). 3D cost distance function makes the analysis of movement in 3D frictions possible. In this paper, we propose an algorithm and efficient data structures to accurately calculate the cost distance in discrete 3D space. Specifically, Dijkstra’s algorithm is used to calculate the least cost between initial voxels and all the other voxels in 3D space. During the calculation, unnecessary bends along the travel path are constantly corrected to retain the accurate least cost. Our results show that the proposed algorithm can generate true Euclidean distance in homogeneous frictions and can provide more accurate least cost in heterogeneous frictions than that provided by several existing methods. Furthermore, the proposed data structures, i.e., a heap combined with a hash table, significantly improve the algorithm’s efficiency. The algorithm and data structures have been verified via several applications including planning the shortest drone delivery path in an urban environment, generating volumetric viewshed, and calculating the minimum hydraulic resistance.

ACS Style

Yaqian Chen; Jiangfeng She; Xingong Li; Shuhua Zhang; Junzhong Tan. Accurate and Efficient Calculation of Three-Dimensional Cost Distance. ISPRS International Journal of Geo-Information 2020, 9, 353 .

AMA Style

Yaqian Chen, Jiangfeng She, Xingong Li, Shuhua Zhang, Junzhong Tan. Accurate and Efficient Calculation of Three-Dimensional Cost Distance. ISPRS International Journal of Geo-Information. 2020; 9 (6):353.

Chicago/Turabian Style

Yaqian Chen; Jiangfeng She; Xingong Li; Shuhua Zhang; Junzhong Tan. 2020. "Accurate and Efficient Calculation of Three-Dimensional Cost Distance." ISPRS International Journal of Geo-Information 9, no. 6: 353.

Research article
Published: 21 October 2019 in Transactions in GIS
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In mountainous regions, solar radiation exhibits a strong spatial heterogeneity due to terrain shading effects. Terrain shading algorithms based on digital elevation models can be categorized into two types: area‐based and point‐specific. In this article, we evaluated two shading algorithms using designed mathematic surfaces. Theoretical shading effects over four Gauss synthetic surfaces were calculated and used to evaluate the terrain shading algorithms. We evaluated the area‐based terrain shading algorithm, Hillshade tool of ArcGIS, and the point‐specific shading algorithm from Solar Analyst (SA) in ArcGIS. Both algorithms showed shading overestimation, and Hillshade showed more accuracy with a mean absolute error (MAE) of 1.20%, as compared to the MAE of 1.66% of SA. The MAE of Hillshade increases exponentially as the spatial extent of the study area increases because the solar position for all locations on the surface is the same in Hillshade. Consequently, we suggest that the surface should be divided into more tiles in Hillshade when the discrepancy in the latitude of the whole surface is greater than 4°. Skyshed, which represents the horizon angle distribution in SA, is error‐prone over more complex terrain because horizon angle interpolation is problematic for such areas. We also propose a new terrain shading algorithm, with solar positions calculated using local latitude for each cell and the horizon angle calculated for every specific time interval, but without projections. The new model performs better than Hillshade and SA with an MAE of 0.55%.

ACS Style

Shuhua Zhang; Xingong Li; Jiangfeng She. Error assessment of grid‐based terrain shading algorithms for solar radiation modeling over complex terrain. Transactions in GIS 2019, 24, 230 -252.

AMA Style

Shuhua Zhang, Xingong Li, Jiangfeng She. Error assessment of grid‐based terrain shading algorithms for solar radiation modeling over complex terrain. Transactions in GIS. 2019; 24 (1):230-252.

Chicago/Turabian Style

Shuhua Zhang; Xingong Li; Jiangfeng She. 2019. "Error assessment of grid‐based terrain shading algorithms for solar radiation modeling over complex terrain." Transactions in GIS 24, no. 1: 230-252.

Journal article
Published: 30 May 2019 in ISPRS International Journal of Geo-Information
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High-quality terrain rendering has been the focus of many visualization applications over recent decades. Many terrain rendering methods use the strategy of Level of Detail (LOD) to create adaptive terrain models, but the transition between different levels is usually not handled well, which may cause popping artefacts that seriously affect the reality of the terrain model. In recent years, many researchers have tried using modern Graphics Processing Unit (GPU) to complete heavy rendering tasks. By leveraging the great power of GPU, high quality terrain models with rich details can be rendered in real time, although the problem of popping artefacts still persists. In this study, we propose a real-time terrain rendering method with GPU tessellation that can effectively reduce the popping artefacts. Coupled with a view-dependent updating scheme, a multilevel terrain representation based on the flexible Dynamic Stitching Strip (DSS) is developed. During rendering, the main part of the terrain model is tessellated into appropriate levels using GPU tessellation. DSSs, generated in parallel, can seamlessly make the terrain transitions between different levels much smoother. Experiments demonstrate that the proposed method can meet the requirements of real-time rendering and achieve a better visual quality compared with other methods.

ACS Style

Liwei Zhang; Jiangfeng She; Junzhong Tan; Biao Wang; Yuchang Sun. A Multilevel Terrain Rendering Method Based on Dynamic Stitching Strips. ISPRS International Journal of Geo-Information 2019, 8, 255 .

AMA Style

Liwei Zhang, Jiangfeng She, Junzhong Tan, Biao Wang, Yuchang Sun. A Multilevel Terrain Rendering Method Based on Dynamic Stitching Strips. ISPRS International Journal of Geo-Information. 2019; 8 (6):255.

Chicago/Turabian Style

Liwei Zhang; Jiangfeng She; Junzhong Tan; Biao Wang; Yuchang Sun. 2019. "A Multilevel Terrain Rendering Method Based on Dynamic Stitching Strips." ISPRS International Journal of Geo-Information 8, no. 6: 255.

Research articles
Published: 08 April 2019 in International Journal of Geographical Information Science
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Adding building labels greatly improves the recognizability of buildings and the readability of three-dimensional (3D) city scenes. However, building label placement is much more complex in 3D scenes than in two-dimensional (2D) maps. The annotation effect is influenced by the attributes of the 3D label, building visibility, and the spatial relationship between the building and viewpoint. In this context, automatically generating building labels for 3D scenes during interactions requires highly complex computations. By contrast, evaluating candidate labels and then selecting the suitable label for each building can be effectively implemented. This paper introduces an approach for labeling buildings in 3D scenes based on evaluations of label candidates. The proposed method predefines a candidate label set for each building. These candidates are then evaluated in terms of their attributes and the relationship between the labels and viewpoint at runtime. The best candidate label, or a situational alternative for each building, is then placed in order of comprehensive label priority to avoid annotation conflicts. A series of experiments demonstrate that this method effectively enhances the correlation of labels and buildings, improves interactive efficiency, and realizes a viable global label layout.

ACS Style

Jiangfeng She; Xinchi Li; Junyan Liu; Yaqian Chen; Junzhong Tan; Guoping Wu. A building label placement method for 3D visualizations based on candidate label evaluation and selection. International Journal of Geographical Information Science 2019, 33, 2033 -2054.

AMA Style

Jiangfeng She, Xinchi Li, Junyan Liu, Yaqian Chen, Junzhong Tan, Guoping Wu. A building label placement method for 3D visualizations based on candidate label evaluation and selection. International Journal of Geographical Information Science. 2019; 33 (10):2033-2054.

Chicago/Turabian Style

Jiangfeng She; Xinchi Li; Junyan Liu; Yaqian Chen; Junzhong Tan; Guoping Wu. 2019. "A building label placement method for 3D visualizations based on candidate label evaluation and selection." International Journal of Geographical Information Science 33, no. 10: 2033-2054.

Journal article
Published: 15 February 2019 in ISPRS International Journal of Geo-Information
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Urban land use information is critical to urban planning, but the increasing complexity of urban systems makes the accurate classification of land use extremely challenging. Human activity features extracted from big data have been used for land use classification, and fusing different features can help improve the classification. In this paper, we propose a framework to integrate multiple human activity features for land use classification. Features were fused by constructing a membership matrix reflecting the fuzzy relationship between features and land use types using the fuzzy c-means (FCM) clustering method. The classification results were obtained by the fuzzy comprehensive evaluation (FCE) method, which regards the membership matrix as the fuzzy evaluation matrix. This framework was applied to a case study using taxi trajectory data from Nanjing, and the outflow, inflow, net flow and net flow ratio features were extracted. A series of experiments demonstrated that the proposed framework can effectively fuse different features and increase the accuracy of land use classification. The classification accuracy achieved 0.858 (Kappa = 0.810) when the four features were fused for land use classification.

ACS Style

Panpan Ge; Jun He; Shuhua Zhang; Liwei Zhang; Jiangfeng She. An Integrated Framework Combining Multiple Human Activity Features for Land Use Classification. ISPRS International Journal of Geo-Information 2019, 8, 90 .

AMA Style

Panpan Ge, Jun He, Shuhua Zhang, Liwei Zhang, Jiangfeng She. An Integrated Framework Combining Multiple Human Activity Features for Land Use Classification. ISPRS International Journal of Geo-Information. 2019; 8 (2):90.

Chicago/Turabian Style

Panpan Ge; Jun He; Shuhua Zhang; Liwei Zhang; Jiangfeng She. 2019. "An Integrated Framework Combining Multiple Human Activity Features for Land Use Classification." ISPRS International Journal of Geo-Information 8, no. 2: 90.

Journal article
Published: 22 January 2019 in Atmosphere
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Solar radiation incident at the Earth’s surface is an essential driver of the energy exchange between the atmosphere and the surface and is also an important input variable in the research on the surface eco-hydrological process. The reanalysis solar radiation dataset is characterized by a long time series and wide spatial coverage and is used in the research of large-scale eco-hydrological processes. Due to certain errors in their production process of the reanalysis of solar radiation products, reanalysis products should be evaluated before application. In this study, three global solar-radiation reanalysis products (ERA-Interim; JRA-55; and NCEP-DOE) in different temporal scales and climate zones were evaluated using surface solar-radiation observations from the National Meteorological Information Center of the China Meteorological Administration (CMA, Beijing, China) and the Global Energy Balance Archive (GEBA, Zürich, Switzerland) from 2000 to 2009. All reanalysis products (ERA-Interim; JRA-55; and NCEP-DOE) overestimated with an annual bias of 14.86 W/m2, 22.61 W/m2, and 31.85 W/m2; monthly bias of 15.17 W/m2, 21.29 W/m2, and 36.91 W/m2; and seasonal bias of 15.08 W/m2, 21.21 W/m2, and 36.69 W/m2, respectively. In different Köppen climate zones, the annual solar radiation of ERA-Interim performed best in cold regions with a bias of 10.30 W/m2 and absolute relative error (ARE) of 8.98%. However, JRA-55 and NCEP-DOE showed the best performance in tropical regions with a bias of 20.08 W/m2 and −0.12 W/m2, and ARE of 11.00% and 9.68%, respectively. Overall, through the evaluations across different temporal and spatial scales, the rank of the three reanalysis products in order was the ERA-Interim, JRA-55, and NCEP-DOE. In addition, based on the evaluation, we analyzed the relationship between the error (ARE) of the reanalysis products and cloud cover, aerosol, and water vapor, which significantly influences solar radiation and we found that cloud was the main cause for errors in the three solar radiation reanalysis products. The above can provide a reference for the application and downscaling of the three solar radiation reanalysis products.

ACS Style

Xiaomin Peng; Jiangfeng She; Shuhua Zhang; Junzhong Tan; Yang Li. Evaluation of Multi-Reanalysis Solar Radiation Products Using Global Surface Observations. Atmosphere 2019, 10, 42 .

AMA Style

Xiaomin Peng, Jiangfeng She, Shuhua Zhang, Junzhong Tan, Yang Li. Evaluation of Multi-Reanalysis Solar Radiation Products Using Global Surface Observations. Atmosphere. 2019; 10 (2):42.

Chicago/Turabian Style

Xiaomin Peng; Jiangfeng She; Shuhua Zhang; Junzhong Tan; Yang Li. 2019. "Evaluation of Multi-Reanalysis Solar Radiation Products Using Global Surface Observations." Atmosphere 10, no. 2: 42.

Research article
Published: 13 January 2019 in Transactions in GIS
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The simplification of 3D building models to effectively reduce model complexity and improve rendering efficiency is an important component of 3D GIS. To reduce the data volume while preserving the model appearance, this article proposes a novel simplification method for complex 3D building models. Texture discontinuities are addressed by developing a new data model that records the mapping relation between the texture coordinates of each vertex and its neighboring triangles. The surface mesh of the building model is then segmented into regions, guided by topology and appearance. Finally, the mesh segmentation information is used to derive an improved error metric that considers both geometric and texture errors, and the texture coordinates are adjusted after each simplification operation. A series of comparative experiments alongside traditional methods demonstrates that our approach achieves a good balance between geometric fidelity and texture preservation, and produces simplified 3D building models with better visual quality.

ACS Style

Jiangfeng She; Xiaoyan Gu; Junzhong Tan; Ming Tong; Chaofan Wang. An appearance‐preserving simplification method for complex 3D building models. Transactions in GIS 2019, 23, 275 -293.

AMA Style

Jiangfeng She, Xiaoyan Gu, Junzhong Tan, Ming Tong, Chaofan Wang. An appearance‐preserving simplification method for complex 3D building models. Transactions in GIS. 2019; 23 (2):275-293.

Chicago/Turabian Style

Jiangfeng She; Xiaoyan Gu; Junzhong Tan; Ming Tong; Chaofan Wang. 2019. "An appearance‐preserving simplification method for complex 3D building models." Transactions in GIS 23, no. 2: 275-293.

Journal article
Published: 20 March 2018 in ISPRS International Journal of Geo-Information
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Specifying the positions and attributes of plants (e.g., species, size, and height) during the procedural generation of large-scale forests in virtual geographic environments is challenging, especially when reflecting the characteristics of vegetation distributions. To address this issue, a novel graph-based neutral landscape model (NLM) is proposed to generate forest landscapes with varying compositions and configurations. Our model integrates a set of class-level landscape metrics and generates more realistic and variable landscapes compared with existing NLMs controlled by limited global-level landscape metrics. To produce patches with particular sizes and shapes, a region adjacency graph is transformed from a cluster map that is generated based upon percolation theory; subsequently, optimal neighboring nodes in the graph are merged under restricted growth conditions from a source node. The locations of seeds are randomly placed and their species are classified according to the generated forest landscapes to obtain the final tree distributions. The results demonstrate that our method can generate realistic vegetation distributions representing different spatial patterns of species with a time efficiency that satisfies the requirements for constructing large-scale virtual forests.

ACS Style

Jiaqi Li; Xiaoyan Gu; Xinchi Li; Junzhong Tan; Jiangfeng She. Procedural Generation of Large-Scale Forests Using a Graph-Based Neutral Landscape Model. ISPRS International Journal of Geo-Information 2018, 7, 127 .

AMA Style

Jiaqi Li, Xiaoyan Gu, Xinchi Li, Junzhong Tan, Jiangfeng She. Procedural Generation of Large-Scale Forests Using a Graph-Based Neutral Landscape Model. ISPRS International Journal of Geo-Information. 2018; 7 (3):127.

Chicago/Turabian Style

Jiaqi Li; Xiaoyan Gu; Xinchi Li; Junzhong Tan; Jiangfeng She. 2018. "Procedural Generation of Large-Scale Forests Using a Graph-Based Neutral Landscape Model." ISPRS International Journal of Geo-Information 7, no. 3: 127.

Article
Published: 27 February 2018 in International Journal of Environmental Research and Public Health
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With the growing interest in studying the characteristics of people’s access to the food environment and its influence upon individual health, there has been a focus on assessing individual food exposure based on GPS trajectories. However, existing studies have largely focused on the overall activity space using short-period trajectories, which ignores the complexity of human movements and the heterogeneity of the spaces that are experienced by the individual over daily life schedules. In this study, we propose a novel framework to extract the exposure areas consisting of the localized activity spaces around daily life centers and non-motorized commuting routes from long-term GPS trajectories. The newly proposed framework is individual-specific and can incorporate the internal heterogeneity of individual activities (spatial extent, stay duration, and timing) in different places as well as the dynamics of the context. A pilot study of the GeoLife dataset suggests that there are significant variations in the magnitude as well as the composition of the food environment in different parts of the individual exposure area, and residential environment is not representative of the overall foodscape exposure.

ACS Style

Qiujun Wei; Jiangfeng She; Shuhua Zhang; Jinsong Ma. Using Individual GPS Trajectories to Explore Foodscape Exposure: A Case Study in Beijing Metropolitan Area. International Journal of Environmental Research and Public Health 2018, 15, 405 .

AMA Style

Qiujun Wei, Jiangfeng She, Shuhua Zhang, Jinsong Ma. Using Individual GPS Trajectories to Explore Foodscape Exposure: A Case Study in Beijing Metropolitan Area. International Journal of Environmental Research and Public Health. 2018; 15 (3):405.

Chicago/Turabian Style

Qiujun Wei; Jiangfeng She; Shuhua Zhang; Jinsong Ma. 2018. "Using Individual GPS Trajectories to Explore Foodscape Exposure: A Case Study in Beijing Metropolitan Area." International Journal of Environmental Research and Public Health 15, no. 3: 405.

Journal article
Published: 31 January 2018 in ISPRS International Journal of Geo-Information
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Because of the smooth interaction of tree systems, the billboard and crossed-plane techniques of image-based rendering (IBR) have been used for tree visualization for many years. However, both the billboard-based tree model (BBTM) and the crossed-plane tree model (CPTM) have several notable limitations; for example, they give an impression of slicing when viewed from the top side, and they produce an unimpressive stereoscopic effect and insufficient lighted effects. In this study, a sphere-board-based tree model (SBTM) is proposed to eliminate these defects and to improve the final visual effects. Compared with the BBTM or CPTM, the proposed SBTM uses one or more sphere-like 3D geometric surfaces covered with a virtual texture, which can present more details about the foliage than can 2D planes, to represent the 3D outline of a tree crown. However, the profile edge presented by a continuous surface is overly smooth and regular, and when used to delineate the outline of a tree crown, it makes the tree appear very unrealistic. To overcome this shortcoming and achieve a more natural final visual effect of the tree model, an additional process is applied to the edge of the surface profile. In addition, the SBTM can better support lighted effects because of its cubic geometrical features. Interactive visualization effects for a single tree and a grove are presented in a case study of Sabina chinensis. The results show that the SBTM can achieve a better compromise between realism and performance than can the BBTM or CPTM.

ACS Style

Jiangfeng She; Xingchen Guo; Xin Tan; Jianlong Liu. 3D Visualization of Trees Based on a Sphere-Board Model. ISPRS International Journal of Geo-Information 2018, 7, 45 .

AMA Style

Jiangfeng She, Xingchen Guo, Xin Tan, Jianlong Liu. 3D Visualization of Trees Based on a Sphere-Board Model. ISPRS International Journal of Geo-Information. 2018; 7 (2):45.

Chicago/Turabian Style

Jiangfeng She; Xingchen Guo; Xin Tan; Jianlong Liu. 2018. "3D Visualization of Trees Based on a Sphere-Board Model." ISPRS International Journal of Geo-Information 7, no. 2: 45.

Article
Published: 31 October 2017 in International Journal of Geographical Information Science
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With the extensive application of virtual geographic environments and the rapid development of 3D visualization analysis, the rendering of complex vector lines has attracted significant attention. Although there are many rendering algorithms in 3D geographic information system (GIS), they are not sufficiently flexible to meet the requirements for rendering linear symbols composed of diverse colors and shapes. However, the interactive rendering of a scene and the accuracy of the symbols are important components for large-scale, complex vector lines. In this paper, we propose a graphics processing unit (GPU)-accelerated algorithm for rendering linear symbols on 3D terrain. Symbol rendering is embedded within the terrain-rendering process, and vector lines are encoded in a 3D texture and then transferred to the GPU. A set of visual properties are used to enrich the expression of symbols with the help of geometric operations in the fragment shader. A series of experiments demonstrate that the proposed method can be utilized for drawing various pixel-exact linear symbols and can achieve real-time rendering efficiency.

ACS Style

Jiangfeng She; Chuang Li; Jiaqi Li; Qiujun Wei. An efficient method for rendering linear symbols on 3D terrain using a shader language. International Journal of Geographical Information Science 2017, 32, 476 -497.

AMA Style

Jiangfeng She, Chuang Li, Jiaqi Li, Qiujun Wei. An efficient method for rendering linear symbols on 3D terrain using a shader language. International Journal of Geographical Information Science. 2017; 32 (3):476-497.

Chicago/Turabian Style

Jiangfeng She; Chuang Li; Jiaqi Li; Qiujun Wei. 2017. "An efficient method for rendering linear symbols on 3D terrain using a shader language." International Journal of Geographical Information Science 32, no. 3: 476-497.

Journal article
Published: 01 October 2017 in Computers & Graphics
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ACS Style

Jiangfeng She; Jianlong Liu; Chuang Li; Jiaqi Li; Qiujun Wei. A line-feature label placement algorithm for interactive 3D map. Computers & Graphics 2017, 67, 86 -94.

AMA Style

Jiangfeng She, Jianlong Liu, Chuang Li, Jiaqi Li, Qiujun Wei. A line-feature label placement algorithm for interactive 3D map. Computers & Graphics. 2017; 67 ():86-94.

Chicago/Turabian Style

Jiangfeng She; Jianlong Liu; Chuang Li; Jiaqi Li; Qiujun Wei. 2017. "A line-feature label placement algorithm for interactive 3D map." Computers & Graphics 67, no. : 86-94.

Journal article
Published: 17 March 2017 in Sustainability
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Reclamation is capable of creating abundant land to alleviate the pressure from land shortages in China. Nevertheless, coastal reclamation can lead to severe environmental degradation and landscape fragmentation. It is quite important to monitor land use and cover change (LUCC) in coastal areas, assess coastal wetland change, and predict land use requirements. The siltation of tidal flats will result in the dynamic growth and continuous expansion of coastal areas. Therefore, the process of land change in coastal areas is different from that under the fixed terrestrial boundary condition. Cellular Automata and Multi-Agent System (CA-MAS) models are commonly used to simulate LUCC, and their advantages have been well proven under the fixed boundary condition. In this paper, we propose CA-MAS combined with a shoreline evolution forecast (CA-MAS-SEF) model to simulate the land change in coastal areas. Meanwhile, the newly increased area, because of the dynamic growth of tidal flats, is considered in the simulation process. The simulation results using the improved method are verified, and compared with observed patterns using spatial overlay. In comparison with simulation results that do not consider the expansion of tidal flats, the Kappa coefficient estimated while considering the dynamic growth of tidal flats is improved from 65.9% to 70.5%, which shows that the method presented here can be applied to simulate the LUCC in growing coastal areas.

ACS Style

Jiangfeng She; Zhongqing Guan; Fangfang Cai; Lijie Pu; Junzhong Tan; Tao Chen. Simulation of Land Use Changes in a Coastal Reclaimed Area with Dynamic Shorelines. Sustainability 2017, 9, 431 .

AMA Style

Jiangfeng She, Zhongqing Guan, Fangfang Cai, Lijie Pu, Junzhong Tan, Tao Chen. Simulation of Land Use Changes in a Coastal Reclaimed Area with Dynamic Shorelines. Sustainability. 2017; 9 (3):431.

Chicago/Turabian Style

Jiangfeng She; Zhongqing Guan; Fangfang Cai; Lijie Pu; Junzhong Tan; Tao Chen. 2017. "Simulation of Land Use Changes in a Coastal Reclaimed Area with Dynamic Shorelines." Sustainability 9, no. 3: 431.

Journal article
Published: 01 February 2017 in Computers & Geosciences
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ACS Style

Jiangfeng She; Yang Zhou; Xin Tan; Xingong Li; Xingchen Guo. A parallelized screen-based method for rendering polylines and polygons on terrain surfaces. Computers & Geosciences 2017, 99, 19 -27.

AMA Style

Jiangfeng She, Yang Zhou, Xin Tan, Xingong Li, Xingchen Guo. A parallelized screen-based method for rendering polylines and polygons on terrain surfaces. Computers & Geosciences. 2017; 99 ():19-27.

Chicago/Turabian Style

Jiangfeng She; Yang Zhou; Xin Tan; Xingong Li; Xingchen Guo. 2017. "A parallelized screen-based method for rendering polylines and polygons on terrain surfaces." Computers & Geosciences 99, no. : 19-27.

Journal article
Published: 16 September 2016 in International Journal of Environmental Research and Public Health
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The serious air pollution problem has aroused widespread public concerns in China. Nanjing city, as one of the famous cities of China, is faced with the same situation. This research aims to investigate spatial and temporal distribution characteristics of fine particulate matter (PM2.5) and the influence of weather factors on PM2.5 in Nanjing using Spearman-Rank analysis and the Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN) method. Hourly PM2.5 observation data and daily meteorological data were collected from 1 April 2013 to 31 December 2015. The spatial distribution result shows that the Maigaoqiao site suffered the most serious pollution. Daily PM2.5 concentrations in Nanjing varied from 7.3 μg/m3 to 336.4 μg/m3. The highest concentration was found in winter and the lowest in summer. The diurnal variation of PM2.5 increased greatly from 6 to 10 a.m. and after 6 p.m., while the concentration exhibited few variations in summer. In addition, the concentration was slightly higher on weekends compared to weekdays. PM2.5 was found to exhibit a reversed relation with wind speed, relative humidity, and precipitation. Although temperature had a positive association with PM2.5 in most months, a negative correlation was observed during the whole period. Additionally, a high concentration was mainly brought with the wind with a southwest direction and several relevant factors are discussed to explain the difference of the impacts of diverse wind directions.

ACS Style

Tao Chen; Jun He; Xiaowei Lu; Jiangfeng She; Zhongqing Guan. Spatial and Temporal Variations of PM2.5 and Its Relation to Meteorological Factors in the Urban Area of Nanjing, China. International Journal of Environmental Research and Public Health 2016, 13, 921 .

AMA Style

Tao Chen, Jun He, Xiaowei Lu, Jiangfeng She, Zhongqing Guan. Spatial and Temporal Variations of PM2.5 and Its Relation to Meteorological Factors in the Urban Area of Nanjing, China. International Journal of Environmental Research and Public Health. 2016; 13 (9):921.

Chicago/Turabian Style

Tao Chen; Jun He; Xiaowei Lu; Jiangfeng She; Zhongqing Guan. 2016. "Spatial and Temporal Variations of PM2.5 and Its Relation to Meteorological Factors in the Urban Area of Nanjing, China." International Journal of Environmental Research and Public Health 13, no. 9: 921.