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# Why the polygon shape changed ??!!

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06-10-2013 01:11 PM
New Contributor
Anyone has the same experience that the shape of polygon changed automatically with some processing.
For example, a perfect circle changed to n-gon shape, n can be between 3 to 7. a round ending road changed to a sharp point.
it happened right after i did some processing, such as split, update. The data looks ok with merge method.

Do you have any idea what happen on my data, and how can i get ride of this trouble. thanks.

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1 Solution

Accepted Solutions
Regular Contributor III
You are probably using a relatively coarse cluster tolerance and/or resolution. Per my experience, unless you have a REALLY good reason to, you should endevor to use the ESRI defaults:

arcpy.env.XYResolution = "0.0005 METERS"
arcpy.env.XYTolerance = "0.001 METERS"

Geoprocessing tools generally default to the most coarse tolerance/resolutiuon. So if you union a FC at 10ft tol with another at 1ft tol, the output will be a 10ft tol (unless you specify otherwise in the tool GUI or the tool's envr. settings).

Here's some reference material: http://resources.arcgis.com/en/help/main/10.1/index.html#//003n00000005000000#GUID-69FA8570-7C64-421... (scroll down a bit more than half way down the page to get to the part about tolerance and resolution).
2 Replies
Regular Contributor III
You are probably using a relatively coarse cluster tolerance and/or resolution. Per my experience, unless you have a REALLY good reason to, you should endevor to use the ESRI defaults:

arcpy.env.XYResolution = "0.0005 METERS"
arcpy.env.XYTolerance = "0.001 METERS"

Geoprocessing tools generally default to the most coarse tolerance/resolutiuon. So if you union a FC at 10ft tol with another at 1ft tol, the output will be a 10ft tol (unless you specify otherwise in the tool GUI or the tool's envr. settings).

Here's some reference material: http://resources.arcgis.com/en/help/main/10.1/index.html#//003n00000005000000#GUID-69FA8570-7C64-421... (scroll down a bit more than half way down the page to get to the part about tolerance and resolution).
New Contributor
thanks. the problem is solved.