I have written a Python script for ArcMap 10 that uses the x/y coords from a shapefile to create perpendicular transects to the existing line. Since these shapefiles are actually rivers the lines are very curved. In order to accurately represent the river's shape there are more points in the curves. My problem is that the program I created takes all of these points to create multiple transects and in the curves it looks like a horrible mess because there are so many points.

Is there any way to create some kind of spacing rule where my program chooses evenly spaced nodes so I can avoid this messy overlap?

  • What is the purpose of the transects? – whuber Sep 1 '11 at 22:12
  • Mr. Huber, creating river transects has various functions in hydrology. Eventually, we'll be able to accurately forecast river discharge based on length and width of the river. My boss has simply asked me to create a program that creates equidistant transects perpendicular to river shapefiles from USGS. It's the whole setting up of equidistant points that is flummoxing me. Thanks – Nick Wissler Sep 2 '11 at 14:15
  • I understand the roles of transects and am not challenging what you're doing. The question is, "why equidistant," given that you started off with irregularly spaced transects. The way the question is worded strongly suggests you are choosing equidistant ones merely as a way to avoid clutter on a map rather than as part of a program of hydrological analysis. – whuber Sep 2 '11 at 14:24
  • I completely understand what you are saying here and you certainly have a point. When I showed my supervisor the fruits of my labor this was his request. I can't say that choosing equidistant points makes the application any less valid, which is why I didn't dispute the request. – Nick Wissler Sep 2 '11 at 14:54
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    I asked a similar question: gis.stackexchange.com/questions/6945/… – Mike T Jan 26 '12 at 23:21

I had been looking for something similar for research I was doing awhile ago but just came across this. If you are still looking for a solution I hope it helps: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//001t00000029000000.htm

We're looking for long answers that provide some explanation and context. Don't just give a one-line answer; explain why your answer is right, ideally with citations. Answers that don't include explanations may be removed.


This python tool splits a polyline into equal segments by a given length plus an eventual remainder.


  • This is close to what I need but not exactly. I may be able to steal portions of the script and employ it as an add on to mine. Thanks for the suggestion. – Nick Wissler Sep 2 '11 at 14:11

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