I have a watershed accumulation file look like this:enter image description here

There are several white lines by visual, and I tried the raster to polyline tool and got this: enter image description here

Are there better ways to extract polyline features from a raster file instead of creating an new shapefile and drawing lines by myself?

1 Answer 1


before you run the raster to polyline tool, you should set a threshold on your accumulation value in order to define the background to zero. This can be done in many ways, e.g. using "reclassify" or using map algebra ( something like : Con( flowacc > threshold , 1, 0) ).

Alternatively, you can use "stream to feature", with a background set to NoData using SetNull( flowac > threshold, flowacc )

  • Thank you, I'm trying to set thresholds to get the best resolution of the output line!
    – Heinz
    Commented Jan 8, 2014 at 7:00
  • @Heinz Setting the threshold is what Stream definition does, and the following functions will vectorize your flow paths.
    – Martin
    Commented Jan 8, 2014 at 7:02
  • @Martin I found that Arc Hydro Tools can't be installed in ArcGIS 10.1, or I miss something?
    – Heinz
    Commented Jan 8, 2014 at 7:08
  • 1
    It sure does, but you tagged your question with 10.0 so I linked to that download. Log in to the ESRI ftp server and download the latest release for 10.1, as explained here. Note however, the password on the linked site is outdated, check forum for valid credentials.
    – Martin
    Commented Jan 8, 2014 at 7:12
  • 1
    Well, those functions does what you need (including extracting polylines). So no, you don't need to find your own way of doing it. And yes, you need to do it but there's a function for that in the proposed workflow! :)
    – Martin
    Commented Jan 8, 2014 at 7:57

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