Some data supplied by Digimap is delivered in large tiles, for example OS VectorMap® District is supplied in 100km by 100km tiles. Such large tiles often cover an area larger than is required. You can clip the area in ArcGIS so it only covers the area you are interested in, and is therefore more manageable.
Create a bounding polygon
In order to clip the area of interest, it is necessary to create a new Shapefile which will be a polygon surrounding the area of interest. This polygon will then be used to clip the data. The steps required are described below.
In ArcCatalog, navigate to the folder containing the downloaded VectorMap District data. If you have used Layer Files to symbolise features navigate to the folder containing these Layer Files.
Right click on the folder and create a new Shapefile.
Give it a suitable name, set it to be a polygon and click on Edit to set the coordinate system to British National Grid.
Open ArcMap, and add your data and also the new Shapefile you created using ArcCatalog in the previous steps.
Navigate to the area of interest.
Open the Editor toolbar , click on Editor, then select Start Editing.
When asked to choose the layer or workspace to edit, select the polygon Shapefile you created and click OK.
A panel titled Create Features should appear on the right, and the created Shapefile should be listed in it.
Make sure the Shapefile is highlighted, and from the Construction Tools section at the bottom of the panel select rectangle.
Digitise around the area you are interested in, and when you have finished click on Editor on the Editor Toolbar, and select Save Edits.
You should now have a polygon Shapefile enclosing your area of interest, which can be used to clip the VectorMap District data so that only the features within your area of interest are visible.
Select the Clip tool which can be found under Analysis Tools > Extract
Select each Shapefile or layer file in turn as the input feature, and select the polygon Shapefile surrounding the area of interest you created previously as the clip feature.
Give it a suitable name and save in an appropriate location.
Click OK to clip the data; once completed a message will be shown at the bottom right of your ArcGIS window:
A duplicate feature will be created for each feature that you selected to be clipped, but the extent of the duplicates will not pass the polygon you created to specify your area of interest. Make sure you un-check (or remove) the original feature classes, so only the clipped data within the area of interest is visible.
, click on Editor, then select Start Editing.
