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Combining bricks to create a catchment

You can create a catchment by selecting any of the standard geographical bricks (e.g. Postal Sectors or Postal Districts) and combining these to form a single catchment.

You can combine different levels of bricks. For example, you can combine some Postal Sectors with a Local Authority District. Any arbitrary bricks (up to a maximum of 50) can be selected from one or more standard geographies, and they do not need to be touching.

Note: Unlike travel time and distance catchments, no centre point is displayed for a catchment which has been created by combining bricks. For a travel time or distance catchment, the centre point represents the origin of the travel time or distance. Catchments created from combining bricks do not have an origin therefore no "centre point" is displayed. This means that the Catchment Centre Point style options are not available from the Edit layer styling pane for a catchment which has been created by combining bricks.

To combine bricks to create a catchment:

Click on the Mapping menu option.
Click on the Catchments option and select Combine Bricks from the drop-down menu. A Combine Standard Geographies window is displayed. Click on the image below to view the window.

From the Combine Standard Geographies window select which geographies you want to combine:

From the Available pane, drag the scroll bar to display the name of a geography (for example Postal Sectors) you want to use and click on its + symbol.
If required, continue to drill down in the tree until you find the specific bricks you want to use. How deep you have to go to find the specific bricks depends on the geography you want to use. For example, Postal Sectors are presented in the tree by Postal Area (e.g. NG), then by Postal District (e.g. NG 13), and finally by Postal Sectors.
Select the specific bricks you want to use. The Selected pane is updated.
Repeat the above steps for any other bricks (e.g. Postal Sectors in other Postal Districts) or any other standard geographies you want to use.

Note: The maximum number of bricks that you can combine is 50. If you select more than 50, a message is displayed on the Combine Standard Geographies window to inform you.

To remove a selected brick, move your mouse over its entry in the Selected pane. A white cross is displayed . Click on the cross to remove the selection.

If you would like to remove all of the selected bricks, click on Clear all at the bottom of the Selected pane.

When you have finished selecting the bricks you want to combine, enter a unique name for the catchment in the Catchment name box.
By default, the catchment will be created and saved to your My Personal Geographies folder. If you want to use a different folder for the catchment then select it from the Folder name drop-down list. Click on the image below to view the window.

Click OK. The Combine Standard Geographies window is closed. A message is displayed to inform you that it is processing the catchment. The name of the catchment is initially displayed on the Layers panel with a progress bar. When processing has been completed, the progress bar is removed, and the catchment is displayed under Saved Geographies.

When processing of the catchment has been completed it is displayed on the map and is available for styling. Click on the image below to view an example.

Note: The catchment is listed on the Manage Data page in the Saved Geographies section under the folder which you chose when you saved it and is automatically given a Brick Geography type and with the currently selected data vintage. It is NOT logged under the Manage Data page Create Catchments - Status section.

You can also create:

a single travel time or distance catchment from a report wizard. For a general procedure, see Creating a catchment from a report.
single or multiple travel time or distance catchments from the Manage Data page or the Mapping page, For more details, see Creating catchments.
a catchment which you draw by hand directly onto the map. For more details, see Drawing a catchment.
a catchment from an imported brick geography. For further details, see Importing a data file.
a catchment from an imported shape file. For further details, see Importing a shapefile.