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Department of Geography


Capture, updating, conversion, and integration of spatial data for geographical information systems

Research staff: Jane Law


In the setting up and management of geographical information systems, spatial data needs to be captured and updated, which very often, involved the problems of data conversion, accuracy, and integration. The methodologies and procedures used for spatial data capture, updating, conversion, and integration for the establishment of a geographical information system in the Highways Department (which used MicroStation and MOSS, a software primarily used for engineering design) using the spatial data from the Lands Department (which used Arc/Info) were studied. Spatial databases usually include significant amounts of secondary data. This is inevitable as database creation proceeds from existing maps and plans rather than carrying out new field surveys. In subsequent updating cycles, changes are detected and recorded using primary data collection techniques. The research aimed to resolve the problems that may arise when integrating primary and secondary spatial data within a layer and ensuring consistency and compatibility with other layers in a land information system. A disk epsilon updating algorithm was proposed for updating of maps, and a program written in C language was developed to implement the algorithm. During the process of updating of spatial data, related problems of data accuracy, conversion, and integration were addressed.


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Figure 1: Operational procedures for data capture, conversion, and integration of LIC (Land Information Centre) digital maps with data from Highways Department.

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Figure 2: Possible discrepancy between primary and secondary map data based on the secondary map data from 1:1000 survey sheet in Hong Kong.

Further readings

  • Law, J., and C.T. Lau (1995). “Automatic updating of digital map.” Proceedings of the AM/FM International Conference XVIII, Baltimore, USA.
  • Law, J., and A. Brimicombe (1994). “Integrating primary and secondary data sources in land information systems for recording change.” Proceedings of the Fig XX International Congress, Melbourne, Australia.
  • Law, J., and C.T. Lau (1994). “The application and potential development of land information system in survey division, Highways Department, Hong Kong.” Paper presented at the Asia GIS/LIS AM/FM and Spatial Analysis Conference, Hong Kong.