Manipulating data » Creating new region files » Selecting

By selecting other CIS files

Again beginning with a new Region file, it is possible to refine a region by using information from an existing dataset. The example used here is to refine a region using any region file and the Ordnance Survey Strategi data to select cells where the Built up area (Towns) is greater than 50%. This is done by using the refine region tool. As can be seen from the image below, selecting the refine region tool produces a dialog box that allows the user to enter the parameters they require. On the left of the screen the user can choose which logical operator they wish to use (in this case replace, but they could choose to add to the existing selection for example). The right of the box allows the user to select which CIS data layer they wish to select from, while specifying whether they want to use the whole dataset, or select a range (in this case > 50).

Above : refining a region using information from existing dataset

The resulting region file can be seen below. This represents the areas of the OS Strategi dataset that have > 50% cover from Built Up Towns. Once again, when this is complete the user can save their work to a new region file.

Above : The resulting region file