I have a set of parcels as illustrated in the image below. There are currently no multi-part features in dataset. What I would like to do is to merge (not the right word) all of the parcels with same address, say 421 for example. I want to have these three polygons as one multi-part polygon, that still has the same geometry, as in it doesn't dissolve the lines.

Image 1

When I have tried this thus far, the lines dissolve resulting in only the boundary being preserved.

Image 2

I feel like there is a super easy was to do this, but I can't find it. I have full access to ArcGIS Advanced and use it to manage the topology of this dataset.

  • 1
    I'm thinking that maybe managing a topology with lines and polygons can help fix this. Any thoughts?
    – Cody Brown
    Jun 8 '13 at 19:36

I think this is an ideal candidate for an ArcGIS Idea (if there is not already one).

The Online Help for Multipart Polygons says (with my bolding):

Keep in mind that parts in a multipart polygon are spatially separated. They can touch each other at vertices, but they cannot share edges or overlap. When you are sketching a multipart polygon, any parts that share an edge will be merged into a single part when you finish the sketch. In addition, any overlap among parts will be removed, leaving a hole in the polygon.

So it seems like you are hitting a limitation in the design of multipart polygon features within shapefiles and geodatabase feature classes.

Why that limitation is there I do not know because your use case seems like a valid one.

  • 1
    I agree. Dang ESRI and it's limitations. Although I can't find a QGIS solution either. I'll post the link on here when I make an ArcGIS Idea on this.
    – Cody Brown
    Jun 8 '13 at 19:35
  • 3
    It's not an ESRI limitation, it's per the OGC Simple Feature Access Standard. *"boundaries of any 2 Polygons that are elements of a MultiPolygon may not 'cross' and may touch at only a finite number of Points," i.e., parts of a multipart polygon can't share an edge. * quote from GeoNet topic
    – user2856
    Sep 20 '15 at 10:23
  • 2
    However, such geometries can be expressed as an OGC simple feature by using GeometryCollection GEOMETRYCOLLECTION ( POLYGON (( 423 357, 423 358, 424 358, 424 357, 423 357 )), POLYGON (( 422 357, 422 358, 423 358, 423 357, 422 357 )), POLYGON (( 424 357, 424 358, 425 358, 425 357, 424 357 ))) They may not be supported in ArcGIS, though.
    – user30184
    Sep 20 '15 at 12:54

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