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The difference between polygons

MauriceMitchell

I have to separate polygon layers, layer 1 and layer 2. The polygons in layer 2 don't completely cover the polygons in layer 1, therefore, I'd like to create a layer 3 that are polygons that aren't overlapped. Also, I'm using ArcGIS Pro 2.4 if that matters.

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Accepted answers

Robert LeClair

I ran a quick Pro session to see the differences. The first image is the 2 overlapping polygons. The second image is the output from Symmetrical Difference. The third image is the output from Erase. Very different views.

All comments

AndresCastillo

PostGIS has a similar tool:
https://postgis.net/docs/ST_Difference.html

AndresCastillo

If you have two polygons, 'A' and B', run the tabulate intersection tool.

Suppose 'A' has zone fields you want to summarize with.

The result will give you an output table that has the percent of the zone field in A that is covered with B.

you can then join this output table back to the A feature class, keeping all target features, and sort on the joined object id to see all of the records where the joined attributes are null (i.e. null objectid's).

This will tell you with A polygons had 0 coverage from the B polygons.

https://pro.arcgis.com/en/pro-app/latest/tool-reference/analysis/tabulate-intersection.htm

MauriceMitchell

Thanks all, I think Erase would be the most useful tool. I will try the others, of course, in order to gain the most knowledge out of the situation.

JoeBorgione

If you use Union, I think you could tease out those polygons that are not common to both. I don't understand the licensing comment in the help docs that states:

Basic: Limited
Standard: Limited
Advanced: Yes

KClarkDev_GIS

Right, but I was just curious if there would be an alternative workflow to achieve this for those that don't have an advanced license.

Robert LeClair

I found the following that describes the differences:

Erase - This tool creates a feature class from those features or portions of features outside the erase feature class.
Symmetrical Difference - This tool creates a feature class from those features or portions of features that are not common to any of the other inputs.

KClarkDev_GIS

I was going to suggest the Erase tool as well, but looks like that also requires an advanced license. I'm not sure if that's a restriction for the OP, but just out of curiosity, any suggestions that wouldn't require that?

Robert LeClair

It's a great (and unseen) tool for such a workflow! Cheers!

JoeBorgione

Cool tool Robert LeClair‌; the antithesis of intersect. I've never noticed it before....

Robert LeClair

You could try the Symmetrical Difference GP tool listed here.

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