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I have a question about repairing a self intersecting polygon shapefile. I have a shapefile containing Polygons (ZM) which have self intersecting features. If I use the "repair geometry" tool, it finds several self intersections and fixes them. Hurray!

But when I make an export of this file (or a selection of it), this export contains self intersections again. This happens on all the tries I've done to handle the problem, which include:

  1. Use the tool "repair geometry", failed;
  2. Dissolve the polygons based on all of their attributes, failed;
  3. Dispose of the ZM properties, and then do all of above, failed;

Even when I import this shapefile into an Geodatabase using ArcCatalog, it imports correctly, but when I make an export from the database, the self intersections are there again.

So any advice on how to fix this problem would be very much appreciated. If anyone could explain why this type of behaviour exists, it would be wonderful.

I'm using ArcGIS 9.3.1 build 4000 (SP2).

Thanks in advance.

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Convert to Lines and fix and overshoots/dangles then rebuild the polygons, GeoWizards is a helpful tool for this. ian-ko.com/ET_GeoWizards/gw_main.htm –  Mapperz Oct 26 '12 at 13:41
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Have you tried to define topology rules for your GDB? It is a painful way to go but I ended up getting valid topologies after all. This is good starting point –  LarsVegas Oct 26 '12 at 14:15
    
I thought there is not an "no self intersections" rule for polygons, only for lines: [link]( webhelp.esri.com/arcgisdesktop/9.2/…) –  Martijn Oct 26 '12 at 14:51
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If possible link up your file and someone might look into it. Sounds like an interesting challenge. I know some of us would love to use open source tools on this one :-) –  ragnvald Oct 30 '12 at 17:12
    
I would say it's all about shapefiles.. they are strange creatures. GDB is always better. btw, all fine with projections? –  najuste Nov 20 '12 at 15:29
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3 Answers

Aside from the ZM issue I find that you can cleanup most topology issues with the identity or union tool. By running your data through these type of tools you create extra features where overlapping occurs. You can also Identify the overlapping areas by running the intersect tool.

None of these solutions are perfect and require you to continue to clean up your data, but by running the tools above, and then creating a spatial id field (lat/lon). You should be able to repair the topological issues.

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I tried multipart to single part in features to develop new layer with extra number of recored as long it don't affect my data, then I run check geometry. when it appeared to be clean I applied dissolve geoprocessing, and it works for me.

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Is it feasible to just manually edit the vertices and remove the self intersections?

I do this a lot (using QGIS because it seems to be less picky about this issue). QGIS also has a 'Check Geometry' tool that will show you where all the self intersections are.

I know you said you're running arc but this might be a helpful approach if nothing else is working.

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