Overlay Analysis: Spatial Join Map

Aim:

To create perform overlay analysis of two (digitized) Feature datasets, using  Spatial Join method.

Procedure:

Concept:   Spatial Join is for geometrically similar or rather same shape features. The demographic datasets, for example is diverse, but for a same location or shapefile in ArcGis terms. Here, however, to illustrate the Overlay analysis using Spatial Join, tool, we will use the same two polygon feature class. This works more like intersect, retaining the water bodies only! Since that’s that only shape geometry that is same or identical to the common features of the two feature classes.

Step 1: Map Input

Identify the two layers that can be digitized from your toposheet or base map. For this session, Forest Area and Waterbodies (Perrinial) were digitized from the given topographic map of Nellore & Cuddapah Districts.  The Polygon Entities were saved into respective shapefiles in target ArcCatalog Folders. 

Step 2: Map Processing

• ·         Digitize the Polygon features for selected entities. Perform Attribute Editing. “Add Field” for “Name” and “Area”.  Specify the Names and calculate geometry to calculate shape area.  (note to calculate geometry, the features need to be on Projected coordinate system).
• ·         Locate the “Spatial Join” tool in Analysis -> Overlay, toolbox.
• ·         Define the Tool Input “Forest” and join feature as “Waterbodies” and specify the target output folder. 
• ·         Click “Ok” to generate the map output

Step 3: Map Display

Create Custom Map Layout with the necessary map elements and Export map to Jpeg format. It’s best to display map outputs in three data frames, one for the Overlay Output ad two for displaying th input feature classes.  One may also choose to Add Attribute table to layout, an option available within the Table options.

Conclusion:

Spatial Join map for the chosen polygon attributes layers are generated using ArcGis 10.1.