RivEX

Summary :: Usage :: Parameters :: Outputs :: Warnings :: Limitations :: Code sample

Summary

Checks for self-intersecting polylines, any found are logged in the error log table.

Usage

This tool checks for self-intersecting polylines. This is a line that crosses over itself which is an illogical situation for a river and can cause errors in subsequent processing of the network. It is strongly advised that all self-intersections are removed from your river network layer.

A self-intersection is usually the result of poor digitising.  They can be hard to spot if the self-intersection is very small.  They often appear as small spurs when zoomed in.  Experience has shown that it is typically the misplacement of a single vertex. A self-intersecting polyline can be corrected by entering edit mode and show the vertices (). You can either move the vertex or right click on the incorrect vertex and delete it. RivEX has a tool that will auto-correct self-intersections which is discussed here.

Any found to have self-intersections have their polyline ID written to an error log table called tblSelfIntersections. If the table already exists then a new table name is created with a simple numeric suffix.

The tool optionally adds the error log table to the map (default) and if selected builds a standard relate between river network layer and error log table. You can use the relate to select and jump to the polyline to streamline your editing experience.

Parameters

Outputs

This tool creates a stand alone table named tblSelfIntersections, if any self-intersections are encountered within the river network.  The table is created in the RivEX workspace folder and stored in the File GeoDatabase found in ..\RivEX_Workspace\ErrorLogs\fGDB_RivEXErrorLogs.gdb

Advice on the structure of the error log table and how it can be used is found within this section of the manual. Take note of the warning if you plan to construct a model using the error log output in subsequent processing.

Warnings

Removing self-intersections does not alter the connectivity of a network but it will shorten your network (albeit a small amount); any previous analysis that involved distances should be re-run.  If you do not remove self-intersections because for example you deem them as insignificant in length, then other RivEX tools you might use will fail.

With the release of ArcGIS Pro 3.2.1 a switch control appears on parameters that accept tables\feature classes, do not interact with it! More advice here.

Limitations

Any selection on the input layer is cleared and then the tool checks all polylines in the river network. This tool uses the python module shapely which must be installed before using RivEX.

Code sample

A minimum code example showing how to call this tool in a python script. This can be run in console or your preferred IDE. If you right click on the tool in the RivEX toolbox and select properties you can view parameter order.

import arcpy

# Import RivEX toolbox
arcpy.ImportToolbox(r"C:\RivEX_ArcPro\RivEX.atbx")

try:
    # Input river Feature Class
    fc = r"C:\Temp\ORN\ORN.gdb\ORN"

    # Run RivEX quality control tool
    res = arcpy.scrQCSelfIntersecting_RivEX(fc, False, False)

    # The rivers Feature Class, a derived output
    fcRivers = res.getOutput(0)
    
    # Get error table
    tblError = res.getOutput(1)

    # Check if error table exists
    if arcpy.Exists(tblError):
        # Count number of rows
        res = arcpy.GetCount_management(tblError)
        n = int(res.getOutput(0))
        if n > 0:
            print(str(n) + " error(s) were recorded")
    else:
        print("No error table created!")
except arcpy.ExecuteError:
    print("FAILED to quality control network")