Find overlapping poygons in same layer

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10-07-2019 08:01 AM
KennethLindhardt1
Occasional Contributor II

I I’m going in to circles here. I got multiple old layers, and I think they has been updated multiple times over the years.

The issue is that they have drawn some features on top of each other, so I can’t get my final area to match the actual area.

The layers consist of many different types, and I don’t want to dissolve, unless it’s on top of each other, since I want to be able to edit the feature attributes on a later point.

So by dissolving, I get my area, but not my necessary amount of features.

I can visually see my overlapping features with intersect, but that wont get me much further. I tried a lot of things, but haven’t succeed yet.

I was wondering if it would be possible to clip overlapping features in the same layer, then I could delete identical.

Or:

Use the subdivided layer to split the dissolved polygon.

It don’t seem that any of the above are possible.

So how would you proceed, if I don’t want any overlapping polygons and they are in the same layer?

I think I must be missing a simple way to do that – the only way I can think of now, is to split by attribute on all my layers, and then erase from top to bottom, and merge the layers back together, but that would be very time consuming.

 

Thanks.    

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2 Replies
JoshuaBixby
MVP Esteemed Contributor

Just thinking off the top, what about doing a Union first.  The overlapping polygons should get attributes from both polygons, which will make selecting them easy.  Then you could do an Eliminate—Data Management toolbox | ArcGIS Desktop 

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DAVIDWADSWORTH_LVVWD
New Contributor II

Are you still working this issue? 

If so, what about the command Find Identical? If you like that, follow up with a read on the Delete Identical which will remove user-defined duplicated polygons!

https://pro.arcgis.com/en/pro-app/2.8/tool-reference/data-management/find-identical.htm

https://pro.arcgis.com/en/pro-app/2.8/tool-reference/data-management/delete-identical.htm

 

The third example in the help (Find Identical)  may be what you are looking for.  Pass the shape (and other fields if applicable) to the command, and it will deliver a table of offending (duplicate) OIDs. 

From the help:

# Name: FindIdentical_Example3.py

# Description: Demonstrates the use of the optional parameter Output only duplicated records.

import arcpy

arcpy.env.overwriteOutput = True

# Set workspace environment

arcpy.env.workspace = "C:/data/redlands.gdb"

in_data = "crime"

out_data = "crime_dups"

# Note that XY Tolerance and Z Tolerance parameters are not used

# In that case, any optional parameter after them must assign

# the value with the name of that parameter

arcpy.FindIdentical_management(in_data, out_data, ["Shape"], output_record_option="ONLY_DUPLICATES")

print(arcpy.GetMessages())

 

I have had luck passing only the "@SHAPE" when looking for duplicate overlap polygons within data. This was a quick and dirty way to identify polygons that were doubled-up due to edit errors without building a topology on your data, or if you can't create a topology on your data.

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