topic Re: Identify polygons that share boundary with straight lines in ArcGIS Pro Questions

Identify polygons that share boundary with straight lines

Anonymous User — Wed, 03 Aug 2022 17:09:55 GMT

I have a polygon dataset (10,000 + features) that was originally digitized in rectangular units (green lines) and has now been merged across the seamlines of the rectangular units using the Dissolve tool. I want to identify polygons that did not dissolve properly due to an incorrect difference in attributes (example: polygons B and C in image) or were mistakenly not digitized on the other side of the rectangular unit and appear "cut off" (polygon D).

Essentially, I want to flag polygons that have a straight line boundaries that are coincident with (or run parallel and very close to) the boundaries of the rectangular units. Polygons that cross the unit boundaries, like polygon A, do not need to be flagged.

I have tried merging the polygon and rectangular unit layers into one dataset and running Polygon Neighbors, but that generates a table that is confusing and lists every shared polygon border (ex: information about polygon B and E's border that I am not interested in). I have also tried the "share a line segment with" relationship in Select by Location, but that has not selected the appropriate features.

Re: Identify polygons that share boundary with straight lines

DanLee — Wed, 03 Aug 2022 17:33:43 GMT

You can try Polygon To Line with default on your blue polygons. The output lines with both LEFT_FID and RIGHT_FID not equal to -1 are the shared boundaries.

https://pro.arcgis.com/en/pro-app/latest/tool-reference/data-management/polygon-to-line.htm

Then you can use Intersect to get the lines that intersect the green polygons. Or Select Layer By Location with Intersect or Share a segment option may work.

Does this work? I hope I didn't misunderstand your description.

Re: Identify polygons that share boundary with straight lines

Anonymous User — Tue, 09 Aug 2022 17:26:41 GMT

Thanks DanLee,

I modified your suggestion to get the closest-to-ideal solution:

1. Created a copy of the blue polygons layer and ran the Snap tool (snap edges of polygons to the edges of the green boundary polygons, within 2 m) because some of these straight, parallel lines that I want to identify were slightly offset from the green polygons.
2. Ran Polygon to Line with default settings for both the blue snapped and green polygons.
3. Select by Location, relationship = "Share a line segment with"

Re: Identify polygons that share boundary with straight lines

DanLee — Tue, 09 Aug 2022 17:39:11 GMT

Excellent! Glad to be able to give you a lead. 🙂