Salisbury district Council, SDC, has had a corporate GIS for 4 years and supplies geographic information to a population of over 100,000 people. With one of the councilâs long term goals of âtransforming business efficiency and customer access to the councilâ it is vital that the data provided to the public is of the highest quality and accuracy. With the introduction of the OS PAI programme, many of the councilâs features on the base mapping were shifted by several metres. Due to the random shift pattern, no simple transformation method could be applied; also additional factors complicate the picture, such as real world change â new houses, changed courses of rivers, new or moved hedgerows, and the quality of the asset data.This is a brief account of how Salisbury District Council Improved its data quality with the help of TENETâs MapRite.
In the picture above: David Piner (left) and Andy Ford â SalisburyTHE CHALLENGEThe PAI movement across the district varied from <1m up to 7m, with real world change affecting 9% of the mapping area. Data quality was also assessed at this time with a number of errors highlighted: 1) Data not snapped to the underlying base map, and/or to adjacent polygons in the same dataset 2) Plotting anomalies, crossovers, spikes, duplicate edges plotted 3) Real world change It was important these data quality issues were corrected as part of the PAI project, otherwise the council would encounter a variety of issues, particularly when running an automated spatial search system. These issues not only affected data that needed transformation under the PAI project but also data captured to the 1:1250 scale mapping. This led the council to look for a solution that included additional tools to improve general data capture, and to manage real world change.CHOOSING THE RIGHT SOLUTIONSDC were drawn to the MapRite product over other competitors following a sample data test revealing which solution would require the most man hours to achieve optimum results. Total estimated cost of the project indicated that MapRite would be the most cost effective. Other considerations were also made: - How the software manages the process (potentially saving time & and controlling quality) - Data format compatibility - The use of software beyond PAI, e.g. real world change management and topological standards (indicating potential lifespan of product) - Will the software evaluate the quality of the data? IMPLEMENTATIONSalisbury District Council started with the automatic correction of their historical planning application data, it being the most business critical, as it is used by the public, interested third parties and the council. During this process the datasets were checked not only for PAI but also for topographical and attribute data quality. The extensive set of metrics and confidence factors in MapRite provided audit information during the automatic process, which was used to quickly identify any geometries with potential issues. MapRiteâs integrated editor allowed any necessary manual changes to be easily performed, with the edits being recorded and reported as part of associated metrics.As the central GIS team were working on behalf of other departments it was considered important to feed back corrective information on data accuracy. MapRiteâs inherent review and reporting facilities were thus time and money savers.THE BENEFITS MINIMUM 90% SUCCESS RATE Only minimal manual intervention required, resulting in significant time and resource savings. EXTENSIVE REVIEW AND REPORTING FACILITIES Audit trail indicates success rates and processes undertaken, ability to export metric data into own GIS software. ON-LINE EDITING TOOLS All facilities in the same tool â optimised effectiveness INDEPENDENCE FROM LINK FILES No dependence on Link data, real world change management possible AUTOMATED DATA CLEANSING FACILITIES As a result of implementing MapRite for their PAI project, Salisbury District Council have complete, consistent and more accurate planning data for the whole of their district, which took two technicians between 8- 9 months work to complete.
Author: Dr Sarah Cole â TENET Technology Ltd
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