Extract Scanned Lines (Conversion Tools)

Summary

Generates polyline features from scanned images.

Illustration

Extract Scanned Lines tool illustration

Usage

The raster must be classified into two classes (binary image) in order to extract features.
Results may be determined by the state of the scanned map at the time of the extraction. To eliminate noise and unwanted pixels it is sometimes necessary to modify the image prior to the extraction of features.
The parameters control which cells are extracted as well as the amount of generalization and smoothing that is applied to the output polyline features.
Generating output polygon features is optional.

Label	Explanation	Data type
Input Scanned Map Image	The input raster dataset. The raster must be classified into two classes (binary image).	Raster Layer
Foreground Value	The foreground value that represents the raster cells that will be extracted to line features.	Long
Output Centerline Features	The output converted polylines.	Feature Class
Intersection Solution	Specifies how polyline features will be created at raster intersections. Raster intersections are locations where three or more raster lines meet. Geometrical—Angles and straight lines will be preserved at intersections. Use this option when the accuracy of angles and straight lines is critical, for example, for site plans or drawings. This is the default. Median—Nonrectilinear (irregular) angles will be handled by averaging directions. Use this option for natural or organic features where lines meet at irregular angles, for example, for environmental mapping. None—Intersections will have no special handling; features will be extracted as is. Use this option when intersections are not present or not important, for example, for elevation contours.	String
Maximum Line Width (Optional)	A filter that enables you to omit larger, thicker lines and focus on extracting only the thinner lines in the raster. This parameter also influences the construction of the output features, making it important to use the most accurate value for your data. Raster lines with a width at or below the maximum line width will be eligible for centerline extraction, while wider elements will be extracted as polygon features (if the Output Polygon Features parameter is specified).	Double
Noise Level (Optional)	The level of noise that will be omitted from the extraction to help improve results.	Double
Compression Tolerance (Optional)	Simplifies lines by removing vertices based on the specified tolerance. Higher compression tolerance values will result in fewer vertices and greater deviation from the original line shape. The compression tolerance indicates the degree of generalization, not map or pixel units.	Double
Apply Smoothing (Optional)	Specifies whether smoothing will be applied to polyline features during extraction. Checked—Smoothing will be applied to the extracted polyline features. Unchecked—Smoothing will not be applied to the extracted polyline features.	Boolean
Smoothing Weight (Optional)	The intensity of smoothing. Higher smoothing weight values produce smoother lines but may cause the output to deviate from the original shape. The smoothing weight value is not a specific map or pixel unit.	Double
Resolve Corners (Optional)	Specifies whether corners will be sharpened or smoothed at locations where raster lines intersect. When extracting natural features (such as contours, soil boundaries, or streams), the resolution of corners may not be as important as other types of map images that represent the built environment. Checked—Corners will be sharpened at locations where raster lines intersect. Unchecked—Corners will be smoothed at locations where raster lines intersect.	Boolean
Maximum Corner Angle (Optional)	The maximum angle of intersecting raster lines that will be considered a corner.	Double
Hole Size (Optional)	If a hole's diagonal length is less than or equal to the specified distance, it will be treated as part of the raster line when extracted. This parameter allows you to ignore holes (small gaps fully enclosed by foreground pixels) in raster lines during extraction. Holes often result from poor source quality or scanning errors.	Long
Close Gaps (Optional)	Specifies whether the tool handles breaks in a raster line and closes gaps that are less than or equal to the specified tolerance resulting in a continuous polyline. Gaps will not be closed at locations where raster lines intersect. Checked—Gaps will be closed for the extracted polyline features. Unchecked—Gaps will not be closed for the extracted polyline features.	Boolean
Gap Tolerance (Optional)	The distance, measured in pixels, that will be used to determine whether gaps between raster lines should be closed during extraction.	Double
Gap Search Angle (Optional)	The angle that will be used to search for gaps in raster lines to enhance extraction results. This parameter is helpful when extracting curved raster lines that contain interruptions, ensuring a more accurate and continuous output polyline.	Double
Output Polygon Features (Optional)	The output feature class that will contain the converted polygons that represent the outline of the raster cells.	Feature Class

arcpy.conversion.ExtractScannedLines(in_raster, foreground_value, out_centerlines, intersection_solution, {line_width}, {noise_level}, {compression}, {smoothing}, {smoothing_weight}, {corners}, {max_corner_angle}, {hole_size}, {close_gaps}, {gap_tolerance}, {gap_search_angle}, {out_polygons})

Name	Explanation	Data type
in_raster	The input raster dataset. The raster must be classified into two classes (binary image).	Raster Layer
foreground_value	The foreground value that represents the raster cells that will be extracted to line features.	Long
out_centerlines	The output converted polylines.	Feature Class
intersection_solution	Specifies how polyline features will be created at raster intersections. Raster intersections are locations where three or more raster lines meet. `GEOMETRICAL`—Angles and straight lines will be preserved at intersections. Use this option when the accuracy of angles and straight lines is critical, for example, for site plans or drawings. This is the default. `MEDIAN`—Nonrectilinear (irregular) angles will be handled by averaging directions. Use this option for natural or organic features where lines meet at irregular angles, for example, for environmental mapping. `NONE`—Intersections will have no special handling; features will be extracted as is. Use this option when intersections are not present or not important, for example, for elevation contours.	String
line_width (Optional)	A filter that enables you to omit larger, thicker lines and focus on extracting only the thinner lines in the raster. This parameter also influences the construction of the output features, making it important to use the most accurate value for your data. Raster lines with a width at or below the maximum line width will be eligible for centerline extraction, while wider elements will be extracted as polygon features (if the `out_polygons` parameter is specified).	Double
noise_level (Optional)	The level of noise that will be omitted from the extraction to help improve results.	Double
compression (Optional)	Simplifies lines by removing vertices based on the specified tolerance. Higher compression tolerance values will result in fewer vertices and greater deviation from the original line shape. The compression tolerance indicates the degree of generalization, not map or pixel units.	Double
smoothing (Optional)	Specifies whether smoothing will be applied to polyline features during extraction. `SMOOTHING`—Smoothing will be applied to the extracted polyline features. `NO_SMOOTHING`—Smoothing will not be applied to the extracted polyline features.	Boolean
smoothing_weight (Optional)	The intensity of smoothing. Higher smoothing weight values produce smoother lines but may cause the output to deviate from the original shape. The smoothing weight value is not a specific map or pixel unit.	Double
corners (Optional)	Specifies whether corners will be sharpened or smoothed at locations where raster lines intersect. When extracting natural features (such as contours, soil boundaries, or streams), the resolution of corners may not be as important as other types of map images that represent the built environment. `CORNERS`—Corners will be sharpened at locations where raster lines intersect. `NO_CORNERS`—Corners will be smoothed at locations where raster lines intersect.	Boolean
max_corner_angle (Optional)	The maximum angle of intersecting raster lines that will be considered a corner.	Double
hole_size (Optional)	If a hole's diagonal length is less than or equal to the specified distance, it will be treated as part of the raster line when extracted. This parameter allows you to ignore holes (small gaps fully enclosed by foreground pixels) in raster lines during extraction. Holes often result from poor source quality or scanning errors.	Long
close_gaps (Optional)	Specifies whether the tool handles breaks in a raster line and closes gaps that are less than or equal to the specified tolerance resulting in a continuous polyline. Gaps will not be closed at locations where raster lines intersect. `CLOSE_GAPS`—Gaps will be closed for the extracted polyline features. `NO_CLOSE_GAPS`—Gaps will not be closed for the extracted polyline features.	Boolean
gap_tolerance (Optional)	The distance, measured in pixels, that will be used to determine whether gaps between raster lines should be closed during extraction.	Double
gap_search_angle (Optional)	The angle that will be used to search for gaps in raster lines to enhance extraction results. This parameter is helpful when extracting curved raster lines that contain interruptions, ensuring a more accurate and continuous output polyline.	Double
out_polygons (Optional)	The output feature class that will contain the converted polygons that represent the outline of the raster cells.	Feature Class

Code sample

ExtractScannedLines example 1 (Python window)

The following sample demonstrates the use of this tool in the Python window:

import arcpy
arcpy.env.workspace = 'C:/data'
arcpy.conversion.ExtractScannedLines(
    in_raster="Scanned_Map_Image", foreground_value=[1],
    out_centerlines=r"C:\data\Extracted_Lines",
    intersection_solution="GEOMETRICAL", line_width=20, noise_level=65,
    compression=0.025, smoothing=True, smoothing_weight=3, corners=True,
    max_corner_angle=135, hole_size=0, close_gaps=True, gap_tolerance=5,
    gap_search_angle=100, out_polygons=r"memory\Extracted_out_polygons"
)

ExtractScannedLines example 2 (stand-alone script)

Extracts lines from a scanned map image

# Name: ExtractScannedLines_2.py
# Description: Extracts lines from a scanned map image
# Requirements: None

# Import system modules
import arcpy
# Set environment settings
arcpy.env.workspace = 'c:/data'

# Set Local Variables
inRaster = "c:/data/ScannedImage"
foregroundValue = [1]
outCenterlines = 'c:/data/output.gdb/ExtractedLines'
intersectionSolution = "GEOMETRICAL"
lineWidth = 20
noiseLevel = 65
compression = 0.025
smoothing = True
smoothingWeight = 3
corners = True
maxCornerAngle = 135
holeSize = 0
closeGaps = True
gapTolerance = 5
gapSearchAngle = 100
outPolygons = 'c:/data/output.gdb/Extracted_out_Polygons'

# Run ExtractScannedLines
arcpy.conversion.ExtractScannedLines(
    inRaster, foregroundValue, outCenterlines, intersectionSolution, lineWidth,
    noiseLevel, compression, smoothing, smoothingWeight, corners,
    maxCornerAngle, holeSize, closeGaps, gapTolerance, gapSearchAngle,
    outPolygons
)

Environments

Current Workspace, Extent, Output Coordinate System, Geographic Transformations, Output CONFIG Keyword, Output XY Domain, Output Z Domain

Licensing information

Basic: No
Standard: No
Advanced: Yes