Over the last decade, more and more cities and even countries worldwide are creating semantic 3D city models of their physical environment based on the international CityGML standard issued by the Open Geospatial Consortium (OGC). CityGML is an open data model and XML-based data exchange format describing the most relevant urban and landscape objects along with their spatial and non-spatial attributes, relations, and their complex hierarchical structures in five levels of detail. 3D city models, which are structured according to CityGML, are often used for various complex GIS simulation and analysis tasks, which go far beyond pure 3D visualization. Due to the large size and complexity of the sometimes country-wide 3D geospatial data, the GIS software vendors and service providers face many challenges when building 3D spatial data infrastructures for realizing the efficient storage, analysis, management, interaction, and visualization of the 3D city models based on the CityGML standard. Hence, there has been strong demand for an open and comprehensive software solution that can provide full support of the aforementioned functionalities. The '3D City Database' (3DCityDB) is a free 3D geo-database solution for CityGMLbased 3D city models. 3DCityDB has been developed as an Open Source and platform-independent software suite to facilitate the development and deployment of 3D city model applications. The 3DCityDB software package consists of a database schema for spatially enhanced relational database management systems (ORACLE Spatial or PostgreSQL/PostGIS) with a set of database procedures and software tools allowing to import, manage, analyze, visualize, and export virtual 3D city models according to the CityGML standard. Within this paper, the software suite is illustrated and explained in detail with respect to the related technical implementations and the underlying conceptual software design. Moreover, the utilization of 3DCityDB in different projects and practical application fields are also presented in this paper.

ABSTRACT:A city may have multiple CityGML documents recorded at different times or surveyed by different users. To analyse the city's evolution over a given period of time, as well as to update or edit the city model without negating modifications made by other users, it is of utmost importance to first compare, detect and locate spatio-semantic changes between CityGML datasets. This is however difficult due to the fact that CityGML elements belong to a complex hierarchical structure containing multi-level deep associations, which can basically be considered as a graph. Moreover, CityGML allows multiple syntactic ways to define an object leading to syntactic ambiguities in the exchange format. Furthermore, CityGML is capable of including not only 3D urban objects' graphical appearances but also their semantic properties. Since to date, no known algorithm is capable of detecting spatio-semantic changes in CityGML documents, a frequent approach is to replace the older models completely with the newer ones, which not only costs computational resources, but also loses track of collaborative and chronological changes. Thus, this research proposes an approach capable of comparing two arbitrarily large-sized CityGML documents on both semantic and geometric level. Detected deviations are then attached to their respective sources and can easily be retrieved on demand. As a result, updating a 3D city model using this approach is much more efficient as only real changes are committed. To achieve this, the research employs a graph database as the main data structure for storing and processing CityGML datasets in three major steps: mapping, matching and updating. The mapping process transforms input CityGML documents into respective graph representations. The matching process compares these graphs and attaches edit operations on the fly. Found changes can then be executed using the Web Feature Service (WFS), the standard interface for updating geographical features across the web.

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Abstract. CityGML is an international standard issued by the Open Geospatial Consortium (OGC) for representing and exchanging Semantic 3D City Models. Due to their large scale and deeply nested structures, the management and visualization of CityGML based models require sophisticated solutions such as the 3D City Database (3DCityDB). The research work presented in this article proposes a high level architecture for extending the 3D City Database to store and manage dynamic properties encoded within a new Application Domain Extension (ADE) of CityGML called Dynamizer ADE. The implementation employs the 3DCityDB 4.2 ADE Plugin Manager, which provides an automatic way for dynamically extending the 3DCityDB to support the storage and management of CityGML models with ADEs. The paper introduces a relational database model for storing and managing the Dynamizer ADE within the 3DCityDB. Further, the research work includes the extension of the 3DCityDB Importer/Exporter in order to import and export CityGML documents including Dynamizer ADE data. 3DCityDB already comes with a Web Feature Service (WFS) interface allowing CityGML features to be requested in standardized ways. The proposed framework enables CityGML Viewers to access static data (using OGC WFS interface) and dynamic data (using the OGC SWE interfaces) in an integrated fashion.

Abstract-Land intensive use is essentially the relationship between land input and output, which means to get the highest output with the least input. The evaluation of land intensive use level is a vital content of urban land management, which can help to provide scientific basis for the governments' decision-making of land management. As a key tool of spatial analysis, ArcGIS plays a very important role in the evaluation of land intensive use. On the basis of discussing the importance of applying GIS to the evaluation work of land intensive use, this paper taking the work flow of the evaluation of intensive land use as the order to introduce the application of ArcGIS in the evaluation work, including image matching, data editing and production of thematic maps, etc., and puts forward the idea of optimizing this work in the future in order to provide reference for theapproaching evaluation of land intensive use and the application of ArcGIS software.Keywords-Land evaluation; ArcGIS;Geodataset; Element class; Featureclass I. FOREWORD It is a great important strategic period now that in China, in which we have both opportunity and challenge in social development, and the pressure of land use will be strengthened. A intensive and efficient land use model in the development zone must be established to ensure a sustainable development of society and economy and to ease the contradiction between land supply and demand. The land intensive utilization evaluation work for the development zone can efficiently control blind expansion, help to tapping the potentiation of inefficiently-use land, enhance the ability of land to participate in macroeconomic regulation and control, and have great significance in building a resource-saving society .In the past, operatorsis usually conduct data statistics and graph calculation and drawing work usually in the Office software and the AutoCAD platform. This kind of work mode has the advantage of simple operation, wide range of application,but the disadvantages are also obvious. Two separate work platform to the combination of graphic and attribute is not close, which often leads toa result of a difference between the final statistical results and the actual measured data.This will load heavy work to check. But with geographical information system (GIS) as a representative of modern science and technology, which can well achieve information acquisition, data processing, space application of automation, intellectualization and visualization,this kind of problem can be easily solved. II. APPLICATION OF GIS IN THE EVALUATIONOF LAND INTENSIVE USE ArcGIS software is now one of the mostmainstream software in the area of geographic information engineering.It is a full range of the highest level of GIS products successfully launched by ESRI Company after the company integrated GIS with database, software engineering, artificial intelligence, network technology and othermainstream computer technology.In the process of land intensive use evaluation,generally the planning departments will provi...