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I am working with a polygon layer of forest age data (one shapefile with many features representing forest stands of different ages) trying to identify places where forest stands in 5 different age classes meet to make grouse habitat management decisions. It would be helpful to automatically generate points where these specified stand boundaries meet. Any suggestions? Thanks!

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What software are you using and how is your data stored? –  HeyOverThere Dec 13 '13 at 17:17
    
Arc 10.1 & data is just shapefiles –  Sam Dec 13 '13 at 17:23
    
By "meet", do you mean boundary touching or overlapping? –  dmahr Dec 13 '13 at 19:10
    
just touching, or even (if possible) within a specified distance –  Sam Dec 13 '13 at 19:25

3 Answers 3

The following model performs the following workflow to accomplish your goals:

  1. Buffer the input forest polygon X meters so that they overlap
  2. Iterate through buffered polygon features and convert to raster (Unique Forest ID should be coded with integer values)
  3. Run Cell Statistics (type: Variety) which calculates the variety (number of unique values) of the inputs.
  4. Reclassify the raster so that all values <= 4 = 0 and values > 4 = 1.

Optional secondary model

  1. Convert binary raster "1" values to polygon.

  2. Iterate feature selection and calculate Mean Center (i.e. centroid). This will place a point on all of the areas where 5 or more unique forest stands meet.

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To recap visually:

Buffer the forest stands polygons. In this case, I buffered 10m.

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Convert buffered polygons to raster and caclulate "unique values" statistics

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Reclassify so that 0 - 4 = 0 and >= 5 = 1

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From the optional secondary model, convert raster "hotspots" to polygons and calculate the mean center of each polygon. These are the areas where 5 or more unique forest stands meet.

enter image description here

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Rather than use Select by Location, how about using the Intersect geoprocessing tool and setting the Output Type parameter to POINT?

From the ArcGIS help.

Polygons can intersect in three ways:

Overlap — Area of overlap can be produced by leaving the Output Type to its default value (LOWEST).

Common boundary/touch at a line — This type of intersection can be produced by specifying LINE as the Output Type.

Touch at a point — This type of intersection can be produced by specifying POINT as the Output Type.

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unless i'm missing something or using the wrong intersect, only two layers can be intersected... –  Sam Dec 16 '13 at 21:32
    
if i split out the age classes into separate layers, i would be working with at least 5 different layers –  Sam Dec 17 '13 at 15:26
    
would it be better/easier to convert to raster? more options for working with the data...? –  Sam Dec 17 '13 at 15:27
    
The number of input layers for intersect varies according to the level of your license. However, you could quite easily use ModelBuilder or Python scripting to get around this. From the help again, "Consider using Union or Intersect multiple times to achieve your desired results. For instance, if there are three feature classes to be intersected, intersect the first two, and intersect the output with the third feature class." ArcGIS Help –  Kevin R Dyke Dec 17 '13 at 15:59

A very simple way to do this is:

  1. Covert polygon feature to point (as vertices)
  2. In point fc, calculate x/y info and concatenate the xy fields together using Field Calculator
  3. Right click on new concatenated field and select Summarize
  4. Join summarized table to point fc on concatenated field

Looking at the count field from the joined summary table you will be able to identify those instances where 5 polygon vertices touch.

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What if 5 polygons meet, but only 2 of them are unique forest age classes? –  Aaron Feb 15 at 18:12

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