Who can use this feature
Owners and Editors of projects within all Professional and Pro + workspaces
Selection requirements for tool to work
At least two overlapping polygon features
Boolean operators are like magic words that help you make decisions and sort things. For example:
AND is like saying, "I want both." If you say, "I want ice cream AND sprinkles," you get both ice cream and sprinkles.
OR is like saying, "I want either one." If you say, "I want ice cream OR cake," you get either ice cream OR cake - both if you're lucky!
NOT is like saying, "I don't want this." If you say, "I want ice cream, but NOT chocolate," you get ice cream that isn't chocolate.
In geospatial analysis we use Boolean operators to help understand relationships between features on Earth. For example:
I want to find areas where there is seagrass AND the area is designated as protected. You'll get the overlapping region. Use the
intersecttool to achieve this.I want to find areas where there is seagrass OR the area is designated as protected. You'll get the a much larger region that will contain all areas that have seagrass, all that are protected, and there may be some areas that correspond to the overlap. Use the
dissolvetool to achieve this.I want to find areas where there is seagrass BUT NOT designated as protected. You will get the area that corresponds to where seagrass is found, but only if it doesn't overlap with areas that are protected. Use the
subtracttool to achieve this.
Simply, the intersect tool identifies overlapping areas between layers or features, while the dissolve tool combines multiple polygon layers into a single layer.
To perform an intersect, dissolve, or subtract operation:
Select two or more overlapping features or layers
Click the intersect, dissolve, or subtract tool from the top menu bar. They are all nested under the dissolve icon.
If you performed the dissolve, intersect, or subtract on multiple features within the same layer, the new feature will be returned within that layer.
If you performed the dissolve, intersect, or subtract between multiple layers, a new layer will be created at the top of your table of contents.
The example below consists of three polygon features in a single layer. Each represent the area where field surveys were conducted. But given there is some overlap, we want to know the total area, without duplication. We use the dissolve tool to achieve this.
Note that the dissolve tool will create multi-part polygons. This means that even if polygons don't overlap, they will become part of the same feature in the table of contents. If you would like separate polygons so show as separate features, you can use split to achieve this. Read on here to learn more about splitting features.