LSGI4321 Geospatial Data Mining and Knowledge Discovery

Individual PaperPau Siu Chung (10525309D)

You are instructed by Lands Department to review their web-based GeoInfo Map applications. Please critically review the strength and limitations of the technologies employed, and suggest improvements.

Introduction

GeoInfo Map is a web-based map portal developed by Land Information Centre (LIC) of the HKSAR Lands Department. It was launched and opened to the public on 26 May in 2010. The main objective of this Map is providing geospatial information to the public via the Internet effectively. It provides a common platform to deliver the geospatial and geo-referenced information from Lands Departments, and others government bureaus and departments (SMO, 2010; ESRI China, 2010).

The user can freely access the GeoInfo Map with Internet service and a modern web browser. The user may also click the “Link to GeoInfo Map” hyperlink on the bureau’s or department’s websites to access to the specific spatial information. The Map allows users to pan and zoom in/out the digital map with multiple scales. At the same time, the users can retrieve the information by searching and filtering the attributes data, or entering the coordinates directly.

On the following, the technologies background and functions of the GeoInfo Map will be introduced. Therefore, the strengths and limitations of the technologies employed will be discussed. Finally, this essay will be concluded by discussing some feasible improvements and enhancement to the current system.

Technologies

To discuss about the technologies employed in GeoInfo Map, the Geospatial Information Hub (GIH) from Lands Department should be introduced first. In 2004, LIC established GIH via the government intranet. GIH project aims at providing a platform to facilitate effective geospatial information exchange among the different government bureaus and departments. It improves the efficiency for the flow of spatial data and the spatial-related collaboration.

GeoInfo Map is an online GIS application which is developed based on the GIH. It can be known as a public version of GIH. Thus, the Map inherits the technological characteristics from the original GIH. In overview, the GeoMap is implemented with a three-tier architecture which is a popular client-server architecture for web application. The three tiers include the presentation tier, the logic (application) tier and the data tier. The presentation tier refers to the client-side components of the system which include the user query interface and data representation interface. The application tier consists of the functional processes to handle the user query and the processing of data. The data tier is composed of the spatial and attributes data, and facilitates the data storage and retrieval.

In GeoInfo Map, the Java Server Page (JSP) engine and the GIS components are involved in the application tier. Once the user accesses to the website, the HTML interface will be dynamically generated by the JSP engine. To respond to the query from client-side, the JSP engine will facilitate the access to the database. The GIS component rasterize the layers of required datasets into image tiles and return them to the client-side interface. On the data tier, the relational database management system (RDBMS) is used to handle the spatial and non-spatial data, and a spatial database engine is involved to achieve the management of spatial data and the connection with GIS.

Strengths

Browser-based ApplicationThe GeoInfo Map is a web-based GIS application that the user can easily access to the system with a common web browser and Internet service. No additional software is needed to install. It can ensure that the accessibility to the general public without GIS background.

The web interface is able to provide some spatial related multimedia to the user in additional to the geometry and attribute data. For example, the geo-referenced site photos, the profile graphs of hiking trail, the related hyperlinks and such.

Centralization of DataThe Geoinfo Map facilitates the centralization of the government geospatial data that the data from different bureaus and departments are put together under a common system. This approach is beneficial to both user experience and technical view.

To the end-user, time and effort would be preserved as the information from varied data sources originally can be accessed under a common platform. In addition to the digital map and the aerial photos from Survey and Mapping Office (SMO), large amount of government information are geospatial-related, for examples, the hiking trails information from the Agriculture, Fisheries and Conservation Department, the declared monuments information from the Antiquities and Monuments Office and the facilities information from other departments. Before the establishment of GeoInfo Map, the users may need to visit the varied government websites to seek the spatial information they want. The process can be time-consuming and annoying as there is no means to search the required information among the separated data storage sites. Further, the usability of the data would be lower as this information is usually represented in form of still images only instead of GIS dataset. In the GeoInfo Map, the information from different sources can be accessed by a common query system and they can be considered at the same time in a common map frame.

In the technical view, since the data are centralized in a common system, the duplicate GIS implementations with similar functionalities can be prevented. The demand of technicians responsible to system administration and data management is also centralized. The resources can be therefore preserved. As the datasets are managed under a common system, the fidelity, consistency and up-to-dateness of the data can be maintained more easily.

Multi-tier ArchitectureAs mentioned earlier, the GeoInfo Map is implemented with the three-tier architecture. Such kind of system architecture provides a great flexibility in system development and maintenance (Wikipedia, 2011).

The interface, the process logic and the data storage components are developed and maintained independently and they can be operated on separated hardware platform. Since the application is broken into separated tiers, the modification on one of the components will not result in a re-write to the whole application. It provides desirable scalability to the overall system that an individual component can be upgraded or replaced independently.

In addition, the multi-tier architecture is also beneficial to the reusability of the functional components. For instance, Lands Department launched a new GIS product called “GeoMobile Map Hong Kong” on June 2011 (GovHK, 2011). This is actually a

mobile version of GeoInfo Map that providing mobile mapping service to the smartphone users. The GeoMobile Map offers the geospatial data and data query functions which are similar to the GeoInfo Map. However, the newly developed user interface is optimal to the smartphone operation and multi-touch technology. The mobile positioning of the device is also integrated. This case reflects the superiority of the reusability that the cost in the development of derived application and system extension can be reduced.

Limitations

2D DatasetsThe design of GeoInfo Map is only deployed for providing 2D datasets distribution. Comparing to the 3D data, the visualization of 2D digital map is relatively abstract that is similar to the traditional paper map. Since the 3D (or 2.5D) map data is becoming popular in order to provide the more concrete views about cities, the attraction of GeoInfo Map may be reduced in the future.

User- friendlinessThe access to the data of the GeoInfo Map is mainly executed by searching query. Due to the limitation of the system, the data shown on the base map will be refreshed every searching session. Therefore, it is impossible to display, compare or analyze the resultant data retrieved by two or more searching query simultaneously.

Spatial Query and Spatial AnalysisThe system only allows the user to input some key words or coordinates to search the geospatial information. The coordinates search is limited to the GPS receiver (or other positioning tools) user and it is not a convenient and reasonable method for the general public to seek spatial information. The key word search function is largely depended on the attribute data. The intelligent search function allows the user to filter the specific facilities (e.g. hotel) in a particular district (e.g. Tsim Sha Tsui). However, there is no means to facilitate data query based on the spatial relationship of the entities.

Data Management In the previous section, the benefits to a common data platform have been discussed. On the contrary, problems can be arisen also because of the centralization of the information from different data sources. Since the information in the GeoInfo

Map are collected from varied government departments that they may be stored in different data format and data structure with different quality. More planning and communication are needed to maintain the centralized information.

Improvements

Enhancements on User OperationTo deal with the limitations mentioned before, some improvements to the user operation on the system. First, query cache function should be implemented to store the result from each searching sessions. The user can turn on or off the individual cache to control the representation of the selected sets of data. Therefore, the user can analyze or compare the interested locations flexibly.

Second, the spatial query or analyst tools should be integrated to the Map. The system can provide the simple spatial functions such as buffering, selection by polygon and seeking nearest facility to a user-defined point. It can enhance the GeoInfo Map from an information provider to a spatial decision-making support system. For example, one can seek the nearest Accident and Emergency Department service around his/her current location. And the parent can filter the schools within a specific distance from their home.

Integration of other GIS ServiceApart from the GeoInfo Map, there are also some other GIS project implemented by other government department to provide spatial information and specific functionalities to the public. For examples, the Statutory Planning Portal (SPP) from Town Planning Board (TPB) is an online GIS to offer the latest statutory plan and planning information. It provides a map frame to display the zonings overlaying on a base map. Further, the Hong Kong eTransport is a public transport route point-to-point search service for Hong Kong. It provides a map interface for setting the origin and destination, and displaying the boarding and alighting points.

The GeoInfo Map provides plenty of geospatial data and a strong searching engine. The SPP and eTransport can be integrated with the GeoInfo Map to improve the map viewing quality and user experience. The base maps of the former systems are significantly simple and only show the relevant information. Although the original map system may be already enough to support its basic functions, the additional information can enhance the overall usability since the geographic entities can be

related with each other physically or sociologically. The rich map information can provide extra potentiality to the integrated systems in order to facilitate a better decision making process.

However, the integration of systems among the different departments should be even more challenging than the integration of data. The difficulties may be come from the non-interoperability of the current applications and the distant information policy of different departments.

Conclusion

In this essay, the background information and the technology employed in the GeoInfo Map were introduced. GeoInfo Map is an online GIS application provided by HKSAR government. It provides abundant amount of geospatial-related information to the general public via the Internet. The Map also acts as a common platform for publishing the spatial information from different government bureaus and departments. It improved the efficiency of the public access to the government geospatial information. The system architecture implemented in the Map is technically flexible for system development and enhancement. The GeoMobile Map Hong Kong is a recent derived application for mobile users based on the GeoInfo Map.

On the other side, this map system is limited by its defeats on the user operations. In addition, the data management to the large-scale centralized geospatial-related data can be a problem if there is no well planning and communication among the stakeholders. Finally, the usability of the system can be improved by providing the spatial query and analysis functionalities. These spatial functions can be beneficial to the general public also. The involved GIS resources can be further utilized adequately by integrating other public GIS application, in order to provide a more complete geospatial information portal to the citizens. However, new challenges must be faced in the integration of separated systems.

Reference

1. GIS for Everyone: The Newly Launched HKSAR GeoInfo Map (2010). Retrieved October 22, 2011 from ESRI China (Hong Kong) Web site: http://www.esrichina-hk.com/news/localNewsArchive.aspx?year=2010&month=6&id=3

2. Government launches mobile mapping service (2011). Retrieved October 22, 2011 from GovHK Web site: http://www.info.gov.hk/gia/general/201106/22/P201106220335.htm

3. Government map service goes online (2010). Retrieved October 22, 2011 from Survey and Mapping Office Web site: http://www.landsd.gov.hk/mapping/text/news/news20100526.htm

4. Hong Kong eTransport (N/A). Retrieved October 22, 2011 from Hong Kong eTransport, Transport Department Web site: http://hketransport.gov.hk

5. Multitier architecture (2011). Retrieved October 22, 2011 from Wikipedia Web site: http://en.wikipedia.org/wiki/Multitier_architecture

6. Statutory Planning Portal (N/A). Retrieved October 22, 2011 from Statutory Planning Portal, Town Planning Board Web site: http://www.ozp.tpb.gov.hk

7. Tsoi, C. W. (2007). HKSAR Geospatial Information Hub (GIH) - A Common Geospatial Information Platform and Spatial Data Portal. FIG working week 2007.