Friday 27 March 2015

arcgis 10.1 - How to identify misaligned corners in PLSS sections


Sometimes PLSS section corners do not align


enter image description here


How could I automate the detection of these corners and generate a new shapefile showing where this occurs? I have a shapefile of 147k section polygons that I would like to analyze.


I am on ArcGIS 10.1 and have Spatial Analyst and 3D analyst licenses.



Based on comments below, I know I could count the sides of polygons to detect some of these occurrences. This would not work in every case where corners are misaligned. Any other suggestions?


On a side note, why do the corners in PLSS sections not always align?



Answer



With a bit of programming, you can identify points where the number of lines that intersect the point is not 4.


You don't mention what version of arcgis, but with the lowest level (Basic, ArcView, or whatever Esri is calling it this week) you should be able to build a MapTopology.


The code in this answer can be edited to accomplish this, by replacing this line:


node.Degree == 1

With


node.Degree != 4

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