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Copyright of Geography & Geographic Information Science is the property of Geography & Geo-Information Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of South Architecture / Nanfang Jianzhu is the property of South Architecture Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objectives: In the large-scale of virtual reality scene, it is difficult to add all graphics data into the video memory for rendering. Removing the occluded objects in advance by visible query technology can reduce the amount of data loaded on the display end to improve the rendering efficiency. Therefore, the research of visible query method for regional objects has important application value for real-time rendering of large-scale urban scene. Methods: We put forward a distributed visible query method based on Map-Reduce. In the map phase, we apply a hierarchical axis-aligned bounding box as viewpoint space partition. When the number of 3D objects in viewpoint space partition exceeds the threshold, the axis-aligned bounding box continues to be divided into sub- boxes. After the above process, the map tasks produce GeoTuples with the VSPID as key and visible query candidate set as value. In the reduce phase, a viewpoint is created for each leaf axis-aligned bounding box where the binary space partitioning trees are build and the visible set is calculated using real-time occlusion algorithm. Results: The experiment results with a building compound, containing more than 200 000 geometric solids, in Shenzhen, China show that: (1) There is no simple linear relationship between the running time of distributed visible query and the number of viewpoint space partitions. (2) Running time and parallelism are not simply inversely proportional. The computational efficiency of each process first increases and then decreases with the increase of parallelism. About 48 parallelism, the process has the highest efficiency. (3) Whether the distributed approach is better than the traditional approach depends on the number of 3D objects. After the amount of 3D objects reaches about 40 000, the distributed algorithm begins to be better than the traditional algorithm. Conclusions: The computational experiments reveal the proposed algorithms outperform competitors in terms of the processing efficiency and feasibility, which can meet the requirement of visible query in large-scale scenarios. [ABSTRACT FROM AUTHOR]

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cartography is a subject whose development was partially restricted due to historical conditions. Compared with the traditional map, driven by new technology and new demands, the mapping objects, representation form, perception channel and user role of maps have all undergone significant changes in the in‐ formation and communication technology (ICT) era. Therefore, the theoretical framework of cartography needs to be further adapted to the ICT era. This paper firstly analyzes the main characteristics of maps in the ICT era, then discusses the concepts and the scope of representation of modern maps in the new era, and finally tries to build the framework of modern maps including the representation object, information abstraction, map representation and map outcomes. This study is expected to clarify the boundary of extended connotation of cartography research and provide corresponding support for the future development of cartography. [ABSTRACT FROM AUTHOR]

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Physical space and social space constitute the dual space of human society. With the rapid de⁃ velopment and popularization of information and communication technology (ICT), information space has grown into the third space, which constitutes the ternary space of human society together with physical space and social space. Smart cities are the intelligent transformation of cities under the condition of ternary space. Its basic engineering logic is to establish the mapping from physical space and social space to informa⁃ tion space, and then feedback physical space and social space through information space to optimize the ur⁃ ban system and solve the urban problems. Geographic information system (GIS) is a technical science that depicts and expresses physical space and social space from the perspective of space. Establishing the intrin⁃ sic relationship of ternary space through GIS will be the logical basis for the construction of smart cities. Firstly, the GIS technology requirements of smart cities is analyzed from four aspects: Digitization, intelli⁃ gence, visualization and openness. Then, a GIS framework for smart cities is proposed, the core of which is shielding complex heterogeneous data downwards and enabling diverse applications upwards. Finally, the key research contents that need to be focused on is discussed, including unified urban data platform con⁃ struction, digital twins and visualization, two⁃way synchronized spatial intelligence, and open platform ser⁃ vices. [ABSTRACT FROM AUTHOR]

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The information and communication technology(ICT)era advances the huge changes of map objects and visualization manners »comparing with traditional maps, which challenges the field of cartographic visualization, either in theory or in technique. This paper provides the pan-map concept and its characteristics,and constructs the dimension system of pan-map visualization. Visualization dimension of pan-map gives significant expansion of cartographic theory framework. Eleven visualization dimensions are listed and six visualization dimensions are displayed in detail. With two cases, the combination and connection of visualization dimensions are explained to illustrate the analysis and application of visualization dimensions. [ABSTRACT FROM AUTHOR]

The development of 3D space planning and management strongly require 3D data to support volumetric representation of 3D space. This paper aims to construct 3D closed building from building information with CityGML LoD3 data and provides the framework and workflow that how to transform and construct 3D closed buildings from CityGML LoD3 data step by step. The semantic objects between 3D property unit and building information are quite different and the 3D space they describe and represent are thorough different. According to the requirement of the geometry of 3D cadastral objects, semantic relationships and object correspondences between CityGML LoD3 and 3D closed building are calibrated. Based on these, the paper gives the methods to extract the geometry data from CityGML and recombines the data to enclose the 3D closed building that satisfy certain 3D geometric rules. The approach in this paper develops a space transformation idea way to construction 3D property unit from building information and can make up the deficiency of the traditional acquisition methods for 3D cadastre. [ABSTRACT FROM AUTHOR]