Clipping Data in ArcMap

This procedure will outline two methods for clipping data within ArcMap: using the select feature tool and clipping files based on a pre-existing boundary. To clip more than one file at a time, use the ArcView 3.2 Batch Clip tool or follow the steps outlined in the ACMLA Bulletin 125, page 18 for clipping multiple files in ArcMap.

• Run ArcMap and add a single data set that requires clipping. For this exercise the DMTI street network will be clipped to isolate the Niagara Region.

Using the Select Feature tool to clip

• Zoom to the area to be clipped using the zoom tool .

• Click the select feature tool .
• In the map window, draw a box around the study area (in this case, the Niagara peninsula). All of the roads encompassed within this box are now selected.

• To create a new shapefile, right-click on the layer name indicated in the Table of Contents. In this case, right-click "ONrds" and select Data>Export Data...

• From the Export Data dialogue box, choose:
  • Export: Selected features
  • Use the same Coordinate System as this layer's source data.
  • Output shapefile or feature class:
    • Use the browse button to navigate to a suitable directory to save the file. (Students may save clipped data in the directory named "students" on the Public Workstation.) Click Save when you have selected a location and file name.
  • Click "Ok" in the Export Data dialogue box to begin the export process.

• When prompted to add the exported data as a layer, click "Yes".

• To de-select the road features choose Selection>Clear Selected Features.
• Turn off the original layer by clicking the check box in the layer listing to the left of the map window.

Using a pre-existing boundary to clip

• Run Arcmap and add the file to be clipped and the boundary file to be used as the "clipper". This example used a regional boundary file from DMTI Spatial.

• Click the Select Feature tool , then click on the polygon representing the Regional Municipality of Niagara. The border should be highlighted as in the image below.

• Click the ArcToolbox to access the various toolsets.
• Click the plus sign + beside Analysis Tools, then Extract. Double-click the "Clip" tool.

• The Clip dialogue box appears. From the dropdown lists, make the appropriate selections.

Input Features (the layer to be clipped): ONrds
Clip Features (the layer to use as the clipper): CANrmn
Output Feature Class (location and filename of the newly clipped layer)

• Click OK to begin the clipping process.

The resulting clipped roads layer is added to the map window.

To perform a batch-clip operation using ArcMap 9.1 see ACMLA Bulletin Number 125, page 18.

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