Suppose an input layer shows a county and an overlay layer shows a national forest. Part of the county overlaps the national forest. We can express the output of an Intersect operation as [county] AND [national forest]. How can we express the outputs of a Union operation and an Identity operation (with the county as the input layer) using the Boolean Connector?

Question

Quizplus · Accepted Answer

The Answer is In Geographic Information Systems (GIS), different operations can be performed to analyze spatial relationships between layers. The Intersect, Union, and Identity operations are among these spatial analysis tools. Here's how we can express the outputs of Union and Identity operations using Boolean logic:

1. Union Operation:
The Union operation combines two layers to create a new layer that includes all areas from both input layers. Any overlapping areas are merged, and attributes from both layers are preserved. Using Boolean logic, the output of a Union operation between a county layer and a national forest layer can be expressed as:

[County] OR [National Forest]

This means that the output layer will include all areas that are in either the county or the national forest or in both.

2. Identity Operation:
The Identity operation is similar to the Intersect operation but retains all features of the input layer (in this case, the county) and only the overlapping parts of the identity layer (the national forest). The output layer will include all features of the county, with additional attributes for the parts that overlap with the national forest. Using Boolean logic, the output of an Identity operation with the county as the input layer can be expressed as:

[County] AND ([County] OR [National Forest])

This expression indicates that the output will include all of the county areas, but for the parts that overlap with the national forest, there will be additional attributes from the national forest layer. Essentially, it's the full county layer plus the intersecting information from the national forest where they overlap.

Suppose an Input Layer Shows a County and an Overlay