Run Thiessen polygons to a specific boundary shapefile

[PatriciaCarbajales-Dale]

I have a point file with township info, but it has no corresponding polygons. I need to create a polygon file, such that for each given county (I do have the county polygon file), each centroid gives an estimated township boundaries which we can then turn into polygons. These polygons need to fit such that they are contained and define the boundary of each county.

[JuttaSchmieder]

Hi,
I have exactly the same problem... Unfortunately, I also do not  have a solution. Did you find one in the mean time? Would be great if you could tell me more...
Regards, Jutta

[GerryGabrisch]

Why not just clip the Thiessen polygons to the county border?

[JuttaSchmieder]

The problem is, that there are many neighbouring polygons. That means if you clip polygons with the county border, there are "leftovers" of the Thiessen polygons in the neighbouring county polygons. Possibly it is easier to understand by looking at the attached jpg, where I tried to illustrate the problem.

[ChrisSnyder]

If you were into scripting, you could:

For each county:
-Build a Thiessen polygon for just the points within the county
-Intersect the county boundary with the Thiessen polygon

Then merge all the intersect polygon outputs together.

[DaleHoneycutt]

Chris has the solution, but you could do the same iteration in ModelBuilder using Iterate Feature Selection (http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//00400000000s000000.htm

(assumes you have 10.0)

[JuttaSchmieder]

Chris and Dale, thank you for your help. Now it works!