Data sharing: The first step towards a spatial data warehouse
Piet Nooij
Data Conversion Lead, AM/FM Project
BC Gas Utility Ltd.,1111 West Georgia Street
Vancouver, BC,Canada V6E 4M4
Telephone: (604) 443-6751
Fax: (604) 443-6599
email:pnooij@bcgas.com
Introduction
Government agencies, public utilities and other organisations, are becoming increasingly
dependent on geographical and other information. Technology has also opened the door
to opportunities to utilise this type of information for a multitude of uses and services that
could not have been imagined even a few short years ago.
Historically, map data has been maintained in a variety of forms - most often on paper.
Storage and maintenance of the information was complex and costly and each
organisation kept their digital data in a variety of formats, making the exchange of
information between organisations very difficult.
In 1995, when BC Gas initiated a paper to digital conversion of its large-scale facilities
plate maps, accurate land base was needed to enable conversion of existing gas facilities
information. BC Gas researched the availability of accurate land base and in several areas
accurate data was available in either a CAD format or on paper. For BC Gas' purposes,
accurate was defined as within 1 metre absolute accuracy. In rural areas, CDMS
(Cadastral Data Management System) data, which is produced from 1:20,000 TRIM
maps and has an accuracy of 5-10 metres, was available.
BC Gas successfully set-up agreements with the Provincial Government and most of the
municipalities in its service area to share the cost of creating accurate digital land base by
digitising existing plans or COGO survey plans. Additional data sets such as address
information databases were imported to further enhance the base maps. As part of these
agreements, BC Gas had to keep records of the owners of the source data to prevent
copyright infringement problems when data had to be delivered to third party
organisations. For each source, a meta-data record was created that identified the source's
owner, data format, projection, datum, quality, and miscellaneous other information. It
was and still is important to keep track of all sources, their accuracy's and to identify any
changes in the land base data for future reference and to aid exchange. BC Gas'
agreements required it to deliver the newly digitised land base and facilities back to each
municipality to allow import into their own municipal GIS systems.
Another data sharing initiative in British Columbia is the PaRIS project, which is an
acronym for Parcel Information System and was initiated by the Ministry of Environment
Lands and Parks. PaRIS is a Geographical Information System used to store parcel,
boundary, remediation sites, heritages sites and other attribute information. The project
has successfully converted parcel information for several municipalities in British
Columbia.
In Alberta, a Spatial Data Warehouse (SDW) initiative was created successfully in 1996
and was a joint venture of the major Alberta utility companies and the Alberta
Government. The SDW has taken over the management (updating, storage and
distribution) of the "Urban Cadastral" and "Rural Cadastral" as well as the topographic
and small scale mapping data sets. The SDW has outsourced the maintenance and
marketing of this information to the private sector.
The development of new digital technologies has made it possible to create, maintain and
distribute digital data in many forms and formats. Distribution to users can be virtually
instantaneous and based on up to date information.
Current Situation
Numerous public and private organisations require up-to-date information of mainly
cadastral and topographical information to meet their day-to-day operational needs.
Local governments and public utilities require:
- Up-to-date information on changes to parcel boundaries and land ownership;
- Accurate street, address and parcel information
- Location of utility infrastructure: hydro, gas, telephone, cable, water and sewer
- Information on Crown tenures (leases, licenses, etc.)
Non-municipal and provincial agencies require similar information. Virtually all of the
information required exists, however it is distributed among a number of different
agencies and organisations.
Fig 1. Data Sets from the different organizations
Issues with the current situation
Distributed information is less than ideal and, as a result, those who require the
information are faced with a number of issues:
- There is no single source from which to access this information. This results in each organisation developing its own information system.
- The information is not available in an integrated fashion. As a result an ad hoc manual integration is quite often carried out.
- In some parts of the province the information is not available in a digital format.
- Each organisation has its own standard or has multiple standards. There is no common mapping or data standard.
- The information is in some parts of the province not up to date.
- The spatial accuracy of the different data sets is not consistent. As a result the integrated data sets do not overlay.
- Many sets of data contain redundant information.
