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world,

once again I encounter something very strange with ArcGIS. I perform a buffer analysis on one side of a polyline. There seems to be a serious accuracy problem and I can't figure out what the cause is. So I hope to find some expertise out there...What I tried without success:

  • change distance settings from 'Field' to 'Linear unit'
  • change distance settings from 'Field' to 'Linear unit'
  • change end type settings from 'ROUND' to 'FLAT'
  • run check geometry tool on the line feature
  • I made a copy of the line and shorted it to area of interest which had some effect but didn't resolve the problem entirely. Especially around the sharp angle the buffer still takes a shortcut!

The buffer is lurching up to 4 meters on the wrong side! See the picture I attached to get an better impression of the problem. Does anyone have an idea what might me causing this behavior? I'm using ArcGIS 9.3.1. with WinXP.

buffer on the left side, hatches in meters

UPDATE

See also my comment below.

I performed the described series of actions (divide, intersect,..) to increase the accuracy level of the source data, placing a vertex every 3 meters along the line. There still remains inaccuracy, again the buffering around the rough turn especially is giving me trouble. See second pic.enter image description here

Cheers, LarsVegas

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Have you checked resolution and tolerance of your input data? –  Alex Markov Jun 7 '12 at 10:55
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I did some more research on the topic and found for example this article. So I increased the vertexes along the line which significantly reduced the error. Nonetheless the error hasn't completely vanished. And there remains the problem of automatically placing new vertices on the line (which is solvable but takes some effort , e.g. divide > intersect > dissolve). –  LarsVegas Jun 7 '12 at 11:12
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What data type are the source and destination: Shapefile, personal gdb, file gdb, ArcSDE gdb? –  RyanDalton Jun 7 '12 at 14:18
    
@ RyanDalton They are both shapefiles. –  LarsVegas Jun 7 '12 at 17:59
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From the images you posted it appears as though the lower left boundary was buffered X distance. What do you hope to accomplish? The solution could be as easy as selecting the polylines you would like to buffer. Could you post an image of the buffers at a larger scale? –  Aaron Aug 23 '12 at 20:03
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2 Answers

I have had similar result when dealing with M and Z Polylines or polylines with arcs. I have had more success removing the M and Z value using X-Tools to "Flatten" the poly.

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Welcome to our site, Joe! Thanks for sharing this idea--it may help somebody (and it fits in with some other recent questions where problems with M and Z values may be implicated). –  whuber Nov 27 '12 at 21:36
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exporting them to a file gdb for re-indexing may be helpful. Also you can check an service pack update for your version.

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Which file do you mean when you refer to them? The buffer-shape? Why do you think that this would help exactly? –  LarsVegas Sep 18 '12 at 18:03
    
This answer does not address the question at all. –  Arabella Sep 28 '12 at 6:20
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