Cul-De-Sac Masks (Cartography)
Summary
Creates a feature class of polygon masks from a symbolized input line layer.
Usage
-
This tool only creates masks at the unconnected ends of lines (also called culs-de-sac). A line end is considered connected if it shares its endpoint with the endpoint of another line. This tool only accepts line layers as input.
This tool is specifically designed to provide line end masks in cases in which lines have been symbolized using a rounded end cap to smooth the transition of line connections. Rather than having lines end with a rounded end cap, the end of the line can be masked using the polygon feature class created with this tool.
-
Masks will be created if the margin distance is 0 or negative. A margin size of 0 will create a polygon that represents the exact shape of the symbolized feature. A negative margin will result in a polygon smaller than the symbolized feature. Generally, a margin value larger than 0 will be specified to produce the desired masking effect.
-
If the input line layer contains multipart line geometries, then cul-de-sac masks are created for all unconnected line ends, including the ends of parts within multipart lines.
-
When creating masks, it is important to know that adding masks to maps adds complexity that will slow map drawing and affect map printing and exporting. Generally, there are three things to consider when creating masks for a map: (1) the number of masks, (2) the complexity of the masks, and (3) whether the masks will be used to mask polygon features filled with marker or line symbols. An increase in the number of masks, having more complex masks, and/or masking against marker or polygon fill symbols will result in slower drawing on your screen. In addition, printing and exporting performance can be poor and even fail to produce valid output, first, because of the large amount of processing required to print and export maps with masks, and second, because of known limitations in how graphic file formats store map export results that have many complicated masks.
-
Margin values are specified in either page units or map units. Most of the time you will want to specify your margin distance value in page units.
Margin value units are interpreted differently depending on which units you choose. If you choose points, inches, millimeters, or centimeters, then masks are created using the margin distance as calculated in page space (you can think of the margin as a distance measured on the paper). The reference scale parameter value is accounted for in this calculation.
If you choose any other units for your margin, then masks are created using the margin distance as calculated in map space (you can think of the margin as a real-world distance measure on the earth). Also, in this case, the reference scale parameter value is not used as part of the calculation.
Syntax
| Parameter | Explanation | Data Type |
input_layer |
Input line layer from which to create masks. | Layer |
output_fc |
The feature class that will contain the mask features. | Feature Class |
reference_scale |
The reference scale used for calculating the masking geometry when masks are specified in page units. This is typically the reference scale of the map. | Double |
spatial_reference |
The spatial reference for which the masking polygons will be created. This is not the spatial reference that will be assigned to the output feature class. It is the spatial reference of the map in which the masking polygons will be used since the position of symbology may change when features are projected. | Spatial Reference |
margin |
The space in page units surrounding the symbolized input features used to create the mask polygon. Typically, masking polygons are created with a small margin around the symbol to improve visual appearance. Margin values are specified in either page units or map units. Most of the time you will want to specify your margin distance value in page units. Margin value units are interpreted differently depending on which units you choose. If you choose points, inches, millimeters, or centimeters, then masks are created using the margin distance as calculated in page space (you can think of the margin as a distance measured on the paper). The reference scale parameter value is accounted for in this calculation. If you choose any other units for your margin, then masks are created using the margin distance as calculated in map space (you can think of the margin as a real-world distance measure on the earth). Also, in this case, the reference scale parameter value is not used as part of the calculation. | Linear unit |
attributes (Optional) |
Determines which attributes will be transferred from the input features to the output features.
| String |
Code Sample
The following Python window script demonstrates how to use the CulDeSacMasks tool in immediate mode.
import arcpy
from arcpy import env
env.workspace = "C:/data"
arcpy.CulDeSacMasks_cartography("C:/data/cartography.gdb/transportation/roads",
"C:/data/cartography.gdb/transportation/cds_polys",
"25000", "", "5 meters", "ALL")
This stand-alone script shows an example of using the CulDeSacMasks tool.
# Name: CulDeSacMasks_standalone_script.py
# Description: Creates masks at the unconnected ends of lines in the input layer.
# Author: ESRI
# Import system modules
import arcpy
from arcpy import env
# Set environment settings
env.workspace = "C:/data"
# Set local variables
input_layer = "C:/data/cartography.gdb/transportation/roads"
outpuf_fc = "C:/data/cartography.gdb/transportation/cds_polys"
reference_scale = "25000"
spatial_reference = x
margin = "5 meters"
attributes = "ALL"
# Execute Cul De Sac Masks
arcpy.CulDeSacMasks_cartography(input_layer, output_fc, reference_scale, spatial_reference, margin, attributes)