Calculate Bridge Overrides (Defense Mapping)
Summary
Calculates the overrides necessary to properly display bridge representations at a given location.
Overrides can be calculated for either line or point bridge features. For a line bridge feature, an override will be calculated for the width of a bridge representation based on the overpassing feature representation that runs through the bridge.
For point bridges, overrides include:
- The rotation angle of a bridge representation based on its overpassing feature
- The position of the bridge, if the original position is not coincident with the overpassing feature
Note:This tool should not be confused with the Create Overpass tool in the Cartography toolbox. The Create Overpass tool generates new bridge features at the intersection of other features; this tool symbolizes existing features.
Usage
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This tool is meant to be used on Topographic Line Map (TLM)-style datasets and requires a well-defined representation structure for point and line bridges.
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A progress indicator displays during calculation. You can cancel the tool execution at any point. However, cancelling only stops further execution; it does not undo any overrides that have already been written.
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This tool works inside and outside edit sessions. If you are already in an edit session, you will be able to undo overrides that have been created.
Syntax
| Parameter | Explanation | Data Type |
in_bridge_features in_bridge_features |
The feature layer that contains the bridge features on which the overrides are calculated. | Layer |
in_overpassing_features in_overpassing_features |
The feature layer that contains the features overpassing the bridges. | Layer |
search_dist (Optional) |
This is the distance by which this tool will buffer point bridge features when identifying the overpassing features, calculated in map units. This parameter is only available for point bridges. The default value is 0 meters. | Linear unit |
expand (Optional) |
Indicates whether or not this tool considers marker layers on overpassing representations when analyzing widths.
| Boolean |
offset (Optional) |
The optional value that can be added to the bridge width override. The default value is 0 points. | Linear unit |
min_length (Optional) |
The optional value that sets the minimum length of a line bridge. The default value is 1.35 millimeters. | Linear unit |
bridge_subtype (Optional) |
The subtype of the feature class from the in_bridge_features parameter that will be modified by this operation. | String |
overpassing_subtype (Optional) |
The subtype of the feature class in the in_overpassing_features parameter that will be used in this operation. The subtype of the feature class in the Overpassing Features With Representations parameter that will be used in this operation. | String |
Code Sample
# Name: CalculateBridgeOverrides.py
# Description: Calculates the overrrides to display bridges properly at a location
# Date: June 2010
# Import arcpy module
import arcpy
from arcpy import env
# Check out a DefenseMapping extension license
arcpy.CheckOutExtension("defense")
# Import the Defense Mapping toolbox - you may have to alter this path
arcpy.ImportToolbox(r'C:\Program Files\ArcGIS\Desktop10.0\ArcToolbox\Toolboxes\Defense Mapping Tools.tbx')
# Set Cartography environment settings
env.cartographicCoordinateSystem = "GEOGCS['GCS_WGS_1984',DATUM['D_WGS_1984',SPHEROID['WGS_1984',6378137.0,298.257223563]],PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]]"
env.referenceScale = "10000"
# Local variables:
in_bridge_features = "C:/Data/10.0/Layers/Bridge.lyr"
in_overpassing_features = "C:/Data/10.0/Layers/Railroad.lyr"
search_dist = "25 Meters"
expand = "NO_EXPAND"
offset = "0 Points"
min_length = "1.35 Millimeters"
# Execute Calculate Bridge Overrides function
arcpy.CalculateBridgeOverrides_defense(in_bridge_features, in_overpassing_features, search_dist, expand, offset, min_length)