Monday, 25 December 2000

Assistant Commissioner for Census and Statistics, Mr Alvin W K Li, said that the new mapping system would provide more accurate and up-to-date geographical data to support the conduct of the 2001C, which will provide comprehensive demographic data for government planning and business analysis.

The 23 000 temporary field workers will rely on the maps produced by the DMS to locate their assignments for household interviews from March 15 to 27 next year.

"The temporary field workers will visit over 2 million households and the collected data will have to be processed under a tight schedule, with basic results to be available in six months," he said.

In the past, map data were stored on paper in C&SD. Manual efforts were required in the maintenance of the map data and production of maps, involving such tasks as photocopying, cutting-and-pasting, and pencil marking on paper. Such effort, which was cumbersome and time-consuming, would have to be repeated each time the base maps from the Lands Department were updated.

As part of the computer system developed for the 2001C, the DMS enables maintenance of map data in electronic form, and provides tools to produce some 100 000 maps for use in the 2001C operation.

The DMS makes use of the whole set of 1:1000 digital maps developed by the Lands Department as the base maps. To meet its own specific needs, C&SD adds on its own data layer, mainly to supplement information of buildings in the non-built-up areas.

"Location maps are a must for the enumeration of quarters in the non-built-up areas, since many individual quarters in these areas do not have addresses and cannot be easily identified. So we ask the enumerators to canvass the areas first and enumerate all quarters found. We must therefore first demarcate the working areas of each enumerator and show the boundaries on maps for the enumerators' reference," Mr Li said.

For the 2001C, C&SD have demarcated the non-built-up areas into some 16 000 small area segments, each containing about 10 quarters. The segment records had been updated through field verification by Census and Survey Officers.

"The DMS is also used to calculate network distance for estimating workload in allocating assignments, and to produce fieldwork progress maps during the 13-day operation. It also allows tagging census results to smaller geographical units to facilitate analysis," Mr Li said.

"We shall look into the possibility of making more use of the DMS, such as sharing the spatial data within C&SD and with other departments, with a view to optimizing the usage of digital map data," Mr Li added.