GNAT

Centerline Tool

The Centerline tool from the FluvialCorridor Toolbox has been modified and imported inside the Stream Network and RiverStyles toolbox. The modifications fix 1) missing centerlines in sections of the valley bottom polygon and 2) extra centerline segments.

Please reference the FluvialCorridor Toolbox for additional information on the Centerline tool.

Usage

Geoprocessing Environments

  • It is recommended to run this tool using 64-bit python geoprocessing.
  • Disable Z and M geometry in the Shape field if topology errors are encountered.
  • Specify a scratch workspace to save/review intermediate temporary files.

Input Parameters

centerline_form

Valley bottom polygon feature class

Should be a valley bottom polygon, which is an data output of the Valley Bottom Extraction Tool (VBET).

Requirements:

  • Single part
  • Only one feature within the polygon feature class

Stream network polyline feature class

A stream network polyline feature class. The Centerline tool will create a centerline in sections of the valley bottom polygon where the stream network exists.

Requirements:

  • Line network should be contained inside the valley bottom polygon feature class input.
  • Remove any “dangles’ or other artificially short line segments attached to the network. Dangles will cause extraneous centerlines to be created.

Disaggregation step

Length used to split the valley bottom polygon margins when creating Thiessen polygons

TIP: Use smaller values (i.e 10m-25m) to maintain detail in narrow reaches.

Smoothing tolerance

Smoothing tolerance for the final centerline.

TIP: 20m recommended.

Output centerline

Output name and location of a polyline feature class containing the new centerline.

Delete temporary files

If checked, deletes temporary processing files after the tool completes.

Outputs

Output Centerline Feature Class

Polyline feature class representing the valley bottom centerline.

Technical Background

Troubleshooting and Potential Issues###

  1. Extraneous centerlines, usually short spurs.
  2. Centerline that does not follow the entire valley length.
  3. Centerline may include bends at the end of some valleys.

References and Resources

  • FluvialCorridor Toolbox
  • Other methods for centerline generation
    • http://www1.pub.informatik.uni-wuerzburg.de/pub/haunert/pdf/HaunertSester2008.pdf
    • http://gis.stackexchange.com/questions/2775/find-tunnel-center-line
    • http://gis.stackexchange.com/questions/29863/creating-centrelines-from-road-polygons-casings
    • https://geonet.esri.com/thread/11548