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I have a very large shapefile with over a million parcels within it.

The problem I am having is that the polygons representing each parcel are very jagged.

What I am looking for is a simple and fast way of essentially "simplifying" these polygons and thus getting cleaner lines out of things.

Naturally, in doing so I need to ensure all parcels are still linked together so there are no spaces between the parcel boundaries.

What's the best way of achieving these objectives?

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    I love parcel data, you won't be able to share some of this data, now would you ;)
    – dassouki
    Dec 14, 2010 at 13:10
  • There are already several question about simplifying geometries on this site? Do none of them address your question? e.g. gis.stackexchange.com/questions/38/…
    – Sean
    Dec 14, 2010 at 15:58
  • The answers to the related questions a , b tend to the theoretical and are not arcgis specific. I think we can tolerate a little duplication here. Dec 14, 2010 at 20:56
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    I do wish the answers here were more than one liners though. For example when Mapperz moves his blog to a different service and ESRI stops serving 9.2 help pages the key ideas, the concepts that makes those real "answers", will be lost and all we'll have are highly recommended broken links. Dec 14, 2010 at 20:59

5 Answers 5

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How about generalization?

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    this goes to the same page is the same as dassouki's "this might help" link (albeit to a different version. No significant changes from 9.2 to 9.3 though). Dec 14, 2010 at 20:50
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As other's have answered, the generalization tools will help you, but to avoid the gaps and slivers, you will need to have the tool resolve the topological errors Simplify Tool

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  • What is this tool called? May 12, 2011 at 0:25
  • @NetConstructor.com: It is the Simplify Polygon tool. It is found in ArcToolbox -> Cartography Tools -> Generalization May 13, 2011 at 19:21
  • Quick followup question on this. Once topological rules are put in place for the shapefiles just topological errors be fixed without simplifying the polygons? I have found that cleaning shapefiles is really difficult if they are messy. Any suggestions for tools (preferably open source) which deal with different topological issues? I have found that many tools can "identify" such issues but few tools can automatically fix issues in bulk. Oct 2, 2011 at 6:11
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http://mapshaper.org/ provides an online applet to do that (see here).

Polygon data are uploaded from a shp file, the simplification level can be controlled on-the-fly with a slider bar, and the simplified data can be imported. Of course, the simplification preserves the topological relationships between polygons (no gaps, no overlaps are created). It is very basic but very quick and efficient! There is maybe a limitation on the input file size.

An example:

before:

alt text

after:

alt text

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  • it's fast and easy to use, but I don't see the option to keep the attributes of the shape file?
    – Cerveser
    Jul 17, 2015 at 12:45
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Here is another option. If you are just worried about the visualisation of these parcels, then if you import them into a File geodatabase you can then create Cartographic Representations over them. Then the cartographic representations can be easily modified so that the parcels are smoothed out. This will only work in a File Geodatabase and will mean that the actual geometry data can stay as it is.

Another option is, if you received the data from another source you can ask them to provide the data again.

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  • What apps are best for this? May 12, 2011 at 0:25
  • my initial suggestion is using ArcGIS Desktop and can be done with an ArcView License and the Cartographic Repesentations. Is this what you are asking?
    – CDBrown
    May 19, 2011 at 4:16
  • Does this mean the the end results would be a raster? Can you provide an example? Oct 2, 2011 at 6:13
  • NO not a Raster, the end result is a feature class with an additional blob field (the Shape Field is a Blob) which allows you to hold new shapes for the symbology. This will allow the creation of a simplification Geometric Effect for the symbols without changing the features at all. Have a look here: help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//…
    – CDBrown
    Oct 10, 2011 at 5:47

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