Building a Web 3D Cadastral GIS in Kaohsiung

Scenario

A good land administration system is an important indicator of whether a country could have further development. Only the government that is able to precisely measure every land within its territory, to control the ownership of each land, and to regulate their transactions will have the capability of resolving disputes between people and make long-term plans to ensure steady economic growth.

As the expansion of modern cities goes on, skyscrapers have been sprung up like mushrooms, and the population has gradually become vertical distributed. As a result, not only land use management but other professional fields, including environmental monitoring, disaster prevention and mitigation, urban planning, and land conservation, are increasingly turning to 3D GIS. When comparing to 2D GIS system, the 3D system provides a more realistic visualization, which significantly helps users analyze data and make decisions more effectively.

For a cadastral map, when 2D data are transformed into 3D, users are allowed to know detailed information like the building height, the actual elevation of a particular cadastre, and the appearance of the building. All of these can clearly demonstrate how they look like in the real world. Therefore, the land administration department can grasp all attributes with ease. If there is any urban renewal plan in the future, it will become much simpler for the development team to formulate a comprehensive plan.

Challenges & Goals

Kaohsiung, the second largest city in Taiwan, is densely populated with more than 10 thousand people per kilometer square living in the urban area. As a result, the Land Administration Bureau of this city has already introduced a 3D cadastral management system since 2007. However, because users need to choose Internet Explorer as browser and download plug-ins to work, many potential users were excluded, and concerns about information security had arisen. Therefore, the administrators decided to move the platform to SuperGIS 3D Earth server and its APIs. The new system should be able to execute the following functions, including data querying based on location and land registration data, viewing cadastral data in 3D, and value-added 3D applications.

Solutions

After an overall assessment by Supergeo project team, a workflow for system construction has been established and can be divided into three parts as below:

  1. First, publish the 3D building models through SuperGIS 3D Earth Server as map services, including simplified and refined ones. Three categories of data are used— image data, land use data and building models. Image data such as aerial photos, satellite images, and other images, are published as WMTS; Land use data are published as vector tiles, which can be used later through the APIs of SuperGIS 3D Earth Server. Lastly, because building models are KML files, SuperGIS 3D Earth Server API can use them directly, which means they don’t need to be published.
  2. Secondly, as mentioned above, use the APIs of SuperGIS 3D Earth Server to create a web GIS application with the published map services.
  3. The last step is displaying, which is to make an interface that integrates the 3D map and various functions for the browser-side. The GIS functions offered on the web GIS include measurement tools, mapping tools, positioning, map querying, map displaying and map overlaying. The project team of Supergeo had collaborated with other teams to transfer these five features onto the new platform.
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Fig. 1 The workflow of deploying a SuperGIS 3D Earth Server
Results & Benefits

The project team of Supergeo and Kaohsiung City Government uses SuperGIS 3D Earth Server as core software to build a 3D cadastral management system. The prospective structure and technologies applied in this system— HTML5 and WebGL are satisfactory. By implementing HTML5 and WebGL, the new system allows people to have a smoother user experience because there is no need to download, install, and update plug-ins constantly. Users can enjoy the realistic 3D effect on the browser directly. Furthermore, these two technologies can seamlessly support different browsers. Users don’t have to stick to Internet Explorer and install related plugins to operate this versatile system.

The new cadastral management system employs 3D GIS technology to replace the original 2D one, which can not only assist the authority to examine the land ownership more comprehensively but improve the overall efficiency and lower the possibility of making wrong registration.

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Fig. 2 Checking the attributes of land by clicking
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Fig. 3 Measuring the height of a building directly
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