Export To DLG (Coverage)
Summary
Creates a Digital Line Graph from a coverage. The DLG is output in DLG-3 Optional (as opposed to Standard) format.
Usage
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Before creating a DLG file using Export To DLG, each node should be sequentially numbered using the Renumber Nodes tool. This will ensure that all arc, node, and polygon feature internal numbers are sequential.
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There are two distribution formats for a DLG file: Standard and Optional. This tool writes a DLG in the Optional format only.
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The DLG To Coverage tool reads and converts Standard or Optional DLG files into a coverage.
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To create a DLG file that contains only point features, you should specify an input coverage that contains one rectangular polygon defining the area covered by the points. Use the name of the point coverage for the Point Coverage option.
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Only one DLG category or layer can be saved in a DLG file created by Export To DLG. A DLG category is equivalent to a layer in a map.
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The internal feature numbers (cover#) are written as the output DLG feature numbers.
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Coverage topology is saved in the DLG file using conventions that are similar to the way topology is stored in a coverage (for example, polygons are defined in clockwise loops, islands as counterclockwise loops; each feature has a unique identification number;and negative numbers for lines indicate reverse directions).
Syntax
| Parameter | Explanation | Data Type |
in_cover |
The coverage to be converted to DLG format. It may contain polygon, line, and node features. | Coverage |
out_dlg_file |
The output DLG-3 Optional format file to be created. | File |
in_point_cover (Optional) |
A coverage containing point features to be written as zero length, degenerate Line (L) records in the output DLG. | Coverage |
in_projection_file (Optional) |
A text file containing input projection parameters to be saved in the DLG header. | File |
x_shift (Optional) |
A constant value to be added to all coverage x-coordinates during the conversion to DLG. X Shift overrides any x-shift parameters found in either projection file or input cover projection definition file. If a value for X Shift is not specified, the default is zero. | Double |
y_shift (Optional) |
A constant value to be added to all y-coordinates during conversion to DLG. Y Shift overrides any y-shift parameters found in either the projection file or input cover projection definition file. If a value for Y Shift is not specified, the default is zero. | Double |
in_header_file (Optional) |
The file containing information to be written into the header of the DLG file. | File |
transform (Optional) |
This operation controls whether a coordinate transformation is performed. Usually, coordinates are transformed to preserve accuracy when written to the DLG.
| Boolean |
Code Sample
The following stand-alone script demonstrates how to export a polygon and a point coverage to DLG format.
# Name: ArcDLG_Example.py
# Description: Exports two coverages to DLG format
# Requirements: ArcInfo Workstation
# Author: ESRI
# Import system modules
import arcpy
from arcpy import env
# Set environment settings
env.workspace = "C:/data"
# Set local variables
inCover = "stand"
outDlgFile = "C:/output/stand.dlg"
inPointCover = "tong_basin4"
inProjectionFile = "stand.prj"
xShift = -500000
yShift = -6000000
inHeaderFile = "standheader.txt"
# Execute ArcDLG
arcpy.ArcDLG_arc (inCover, outDlgFile, inPointCover, inProjectionFile,
xShift, yShift, inHeaderFile, "")