ArcMap

Raster to Polyline

Summary

Converts a raster dataset to polyline features.

Usage

  • The input raster can have any valid cell size greater than 0, and may be any valid integer raster dataset.

  • The Field parameter allows you to choose which attribute field of the input raster dataset will become an attribute in the output feature class. If a field is not specified, the cell values of the input raster (the VALUE field) will become a column with the heading Grid_code in the attribute table of the output feature class.

  • The following graphic illustrates how the input raster is vectorized when it is converted to a polyline feature output. The result is presented for both the settings of the Simplify parameter.

    Illustration of output with different simplify options
    Comparing the output with different simplify options

  • If Extent is specified in the environment setting, and the lower-left corner of the output extent does not match with any cell corner of the input raster, in the processing, a shift of the cell alignment of the input raster will be performed to match the specified extent. This shift will trigger a resampling of the input raster using the Nearest Neighbor method. Consequently, the output features will be shifted as well, and as a result, the output features may not overlay the original input raster exactly. You can avoid this shift by using the input raster as the Snap Raster in the environment.

Syntax

RasterToPolyline_conversion (in_raster, out_polyline_features, {background_value}, {minimum_dangle_length}, {simplify}, {raster_field})
ParameterExplanationData Type
in_raster

The input raster dataset.

The raster must be integer type.

Raster Layer
out_polyline_features

The output feature class that will contain the converted polylines.

Feature Class
background_value
(Optional)

Specifies the value that will identify the background cells. The raster dataset is viewed as a set of foreground cells and background cells. The linear features are formed from the foreground cells.

  • ZERO —The background is composed of cells of zero or less or NoData. All cells with a value greater than zero are considered a foreground value.
  • NODATA —The background is composed of NoData cells. All cells with valid values belong to the foreground.
String
minimum_dangle_length
(Optional)

Minimum length of dangling polylines that will be retained. The default is zero.

Double
simplify
(Optional)

Simplifies a line by removing small fluctuations or extraneous bends from it while preserving its essential shape.

  • SIMPLIFY —The polylines will be simplified into simpler shapes such that each contains a minimum number of segments. This is the default.
  • NO_SIMPLIFY —The polylines will not be simplified.
Boolean
raster_field
(Optional)

The field used to assign values from the cells in the input raster to the polyline features in the output dataset.

It can be an integer or a string field.

Field

Code sample

RasterToPolyline example (Python window)

Converts a raster dataset to polyline features.

import arcpy
from arcpy import env
env.workspace = "c:/data"
arcpy.RasterToPolyline_conversion("flowstr", "c:/output/streams.shp", "ZERO",
                                   50, "SIMPLIFY")
RasterToPolyline example (stand-alone script)

Converts a raster dataset to polyline features.

# Name: RasterToPolyline_Ex_02.py
# Description: Converts a raster dataset to polyline features.
# Requirements: None

# Import system modules
import arcpy
from arcpy import env

# Set environment settings
env.workspace = "C:/data"

# Set local variables
inRaster = "flowstr"
outLines = "c:/output/flowstream.shp"
backgrVal = "ZERO"
dangleTolerance = 50
field = "VALUE"

# Execute RasterToPolygon
arcpy.RasterToPolyline_conversion(inRaster, outLines, backgrVal, 
                                  dangleTolerance, "SIMPLIFY", field)

Environments

Licensing information

  • ArcGIS Desktop Basic: Yes
  • ArcGIS Desktop Standard: Yes
  • ArcGIS Desktop Advanced: Yes

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