Skyline Barrier (3D Analyst)
Summary
Generates a multipatch feature class representing a skyline barrier or shadow volume.
Illustration
Usage
The barrier resembles a triangle fan formed by drawing a line from the observer point to the first vertex of the skyline, then sweeping the line through all of the vertices of the skyline. Consider using this tool to determine whether features, such as multipatches representing buildings, violate the barrier by protruding up through it, or whether a proposed building would alter the skyline.
Use the Skyline tool first to generate a skyline or silhouette. A silhouette would produce a volumetric representation of the shadow cast by light coming from the observation point.
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The Minimum Radius and Maximum Radius parameters define the length of the triangle edges emanating from the observation point. If the default value of 0 is specified for the Minimum Radius or Maximum Radius, then no minimum or maximum length is used in the analysis.
If you choose to create a closed multipatch, then the output will be extruded to the height defined in the Base Elevation parameter, and a horizontal ring will be created to form the bottom of the closed geometry. If the specified base elevation is greater than the highest vertex in the skyline barrier, then the base will actually be a ceiling.
The new multipatch feature class will have the following fields:
- OBSV_PT_ID—The FID of the observer point used to create the skyline which, in turn, was used to create this skyline barrier multipatch.
- ORIGFTR_ID—The FID of the original feature, such as a building, represented by the skyline segment or silhouette which was used to create this shadow volume.
- SILHOUE_ID—The FID of the multipatch feature (silhouette) used to create this shadow volume (for silhouettes only).
Syntax
| Parameter | Explanation | Data Type |
in_observer_point_features |
The point feature class containing the observer points. | Feature Layer |
in_features |
The input line feature class which represents the skylines, or the input multipatch feature class which represents the silhouettes. | Feature Layer |
out_feature_class |
The output feature class into which the skyline barrier or shadow volume is placed. | Feature Class |
min_radius_value_or_field (Optional) |
The minimum radius to which triangle edges should be extended from the observer point. The default is 0, meaning no minimum. | Linear Unit; Field |
max_radius_value_or_field (Optional) |
The maximum radius to which triangle edges should be extended from the observer point. The default is 0, meaning no maximum. | Linear Unit; Field |
closed (Optional) |
Whether to close the skyline barrier with a skirt and a base so that the resulting multipatch will appear to be a solid.
| Boolean |
base_elevation (Optional) |
The elevation of the base of the closed multipatch; it is ignored if the barrier is not to be closed. The default is 0. | Linear Unit; Field |
project_to_plane (Optional) |
Whether the front (nearer to the observer) and back (farther from the observer) ends of the barrier should each be projected onto a vertical plane. This is typically checked (turned on) in order to create a shadow volume.
| Boolean |
Code Sample
The following sample demonstrates the use of this tool in the Python window:
import arcpy
from arcpy import env
arcpy.CheckOutExtension("3D")
env.workspace = "C:/data"
arcpy.SkylineBarrier_3d("observers.shp", "skyline_outline.shp", "barrier_output.shp")
The following sample demonstrates the use of this tool in a stand-alone Python script:
'''****************************************************************************
Name: Skyline Barrier Example
Description: This script demonstrates how to use the
Skyline Barrier tool.
****************************************************************************'''
# Import system modules
import arcpy
import exceptions, sys, traceback
from arcpy import env
try:
# Obtain a license for the ArcGIS 3D Analyst extension
arcpy.CheckOutExtension('3D')
# Set environment settings
env.workspace = 'C:/data'
# Set Local Variables
inPts = 'observers.shp'
inLine = 'skyline.shp'
outFC = 'output_barriers.shp'
minRadius = '0 METERS'
maxRadius = '200 METERS'
#Execute SkylineBarrier
arcpy.SkylineBarrier_3d(inPts, inLine, outFC, minRadius,
maxRadius, 'CLOSED')
except arcpy.ExecuteError:
print arcpy.GetMessages()
except:
# Get the traceback object
tb = sys.exc_info()[2]
tbinfo = traceback.format_tb(tb)[0]
# Concatenate error information into message string
pymsg = 'PYTHON ERRORS:\nTraceback info:\n{0}\nError Info:\n{1}'\
.format(tbinfo, str(sys.exc_info()[1]))
msgs = 'ArcPy ERRORS:\n {0}\n'.format(arcpy.GetMessages(2))
# Return python error messages for script tool or Python Window
arcpy.AddError(pymsg)
arcpy.AddError(msgs)