[UW-GIS-L] Calculating shared boundary

[Phil Hurvitz]

In the old arc-node topology ("coverage") model (ArcInfo Workstation), 
polygons were composed of areas bounded by sets of arcs. A polygon 
bounded by 4 neighbors would have at least 4 bounding arcs. Each 
polygon/arc combination is tracked by the software and can be accessed 
through the attribute tables. Under this model it was fairly easy to 
determine the bounding length between neighboring polygons.

In the newer models (shapefile, geoDB), polygons are composed of 
self-contained "rings" so a polygon with 4 neighbors has no data-driven 
identification of its neighbors, so with the basic polygon data model I 
don't believe it is possible to determine shared length.

A method could be developed that first uses the polygon to line tool in 
ArcGIS, and then performs a loop that tallies up for each polygon the 
shared length with each neighbor, but that would probably require some 
programming.

-P.

  **************************************************************
      Phil Hurvitz, MFR | PhD Student, Urban Planning | CBE
          1107 NE 45th Street, Suite 535 | Box 355740
  University of Washington, Seattle, Washington  98195-5740, USA
  phurvitz at u.washington.edu | http://gis.washington.edu/phurvitz
  "What is essential is invisible to the eye." -de Saint-Exupéry
  **************************************************************


Svetlana A Kushch wrote:

> 

> For a class project I have a task to calculate a part of the polygons' 

> perimeter (in units and in % to the perimeter) which is shared with its 

> 'neighbors'. How can I do it in ArcGIS? I searched in the ArcGIS Desktop 

> Help but there was nothing that can be applied.

> 

> Thank you.

> Svetlana Kushch

> kushch at u.washington.edu

> 

> 

> 

> 

> 

> 

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