ArcGIS 10 Desktop : buffers are being cut off

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08-14-2013 08:20 AM
YvanStg
New Contributor II
Hello,

I recently encountered a problem with the Geoprocessing/buffer tool : I want to create 186km individual (disolve=NONE) buffers around a set of points and the resulting buffers located on the edge of my dataset are being cut off.
I thought it could be due to a wrong map extent but it doesn't seem to be the case.
Moreover, when adding new points outside of my dataset, their buffers are also being cut off. See screenshot (pink : full dataset/ blue: new points).[ATTACH=CONFIG]26700[/ATTACH]

Any idea what could cause this ?
It is not the first time I use the buffer tool and I haven't had any problems with it in the past.

Thanks a lot,
Yvan
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13 Replies
DuncanHornby
MVP Frequent Contributor
Are they actually being cut? You can test this just by looking at the area of the buffer polygon. If they are the same then it would suggest you have a clipping extent set on the DataFrame.

If they are genuinely being cut this would suggest an extent has been set on the tools environment settings, or the applications environment settings or the the model environment settings.
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YvanStg
New Contributor II
Hi Duncan, thanks for your reply.

yes, they are being cut "for real": the polygons' areas are not equal (nor close to equal). See the screenshot of the attribute table: polygon2, which is the blue one at the bottom left corner, as an area half the size of the others in the same layer.[ATTACH=CONFIG]26704[/ATTACH]

The extent varies with the datasets (blue and pink buffers are cut at different extents), so it seems right that the extent has been set on the tool environment settings.
Is there any way to change that ?
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ChrisSnyder
Regular Contributor III
Looks like you are using a geographic projection. What are the lat/lng of some of the ones being cut off. Do the buffers extend into another hemisphere?
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YvanStg
New Contributor II
Hi Chris,

I do use a projection (WGS 1984 World Mercator). All of my points are in the Northern hemisphere, between -40/-90 Lon and 50/9 Lat. See map attached[ATTACH=CONFIG]26706[/ATTACH]
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ChrisSnyder
Regular Contributor III
Hmmm... You didn't accidently set the analyis extent environment variable (http://resources.arcgis.com/en/help/main/10.1/index.html#/Output_Extent/001w00000009000000/)? Although I wouldn't think it would cut off the buffer like that, but maybe.
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YvanStg
New Contributor II
My Processing Extent in Environment Settings is "Default". [ATTACH=CONFIG]26707[/ATTACH]
So, if I understand well, this means that the extent is based on the input of the Buffer tool. Now, it could explain why I have different extents for different datasets/inputs, but not why the results of the tool are cut off. Or that can be the reason ?...
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ChrisSnyder
Regular Contributor III
I'm baffeled - what if you use a non-geographic coordinate sytem? Try projecting your points to something like Albers Equal Area Coinic and then try buffering (or maybe just try to specify Albers as the output Spatial ref in the envr variables). Do you get the same issue?
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ChrisSnyder
Regular Contributor III
Can you post your point FC (should be small enough to post here, right?)?
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YvanStg
New Contributor II
I just tried projecting in North America Albers Aqual Area Conic and the buffer polygons come out whole: none of them are being cut off.
Now why this happens, I don't understand...
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