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Using ArcGIS 10.2 for Desktop, I am trying to create a polygon shape(s) from a raster image. Is there a way to indicate areas I do not want included in the shape. Similar to a buffer I suppose, but that will not do what I want it to do. I have the image below, top is an inset. I want the "main" areas to be within a polygon, but if a point is too far out it will be left out, this can be arbitrary depending on the location and position of other points. Is there any way to control this? I have looked at using Minimum Bounding Geometry, Convex hulls, etc. The main problem is I need to do this for over 200 files and aside from hand drawing a polygon around each shape, is there any better way to do it? Russia

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    My first suggestion would be to take a look at the Generalization toolsets (Cartography or Spatial Analyst), particularly Aggregate Polygons. The problem is the arbitrary bit - if there's no consitent criteria for distance to include/exclude, there isn't really a tool that can do it for you since you are effectively drawing arbitrary boundaries. – Chris W Aug 14 '14 at 20:53
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a good trick, but you'll need to define a distance, is to use positive and negative buffers alternatively. 1) create a buffer around your polygons with a positive size of N meters (with dissolve boundaries) 2) create a negative buffer on the result with a size of -(N+x) 3) create a positive buffer with a size of x. Small patches will be grouped together if they are close, and will disappear if they were isolated. You'll need to tune the values of N and x for optimal results.

  • I've used that trick many times, also works to 'clean up' ragged boundaries. The trick is, as you said, the distance to buffer by which will be trial and error and judging by your picture it will be difficult to find a one-size-fits-all solution, you may need to do multiple iterations to aggregate properly. – Michael Stimson Aug 14 '14 at 22:15

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