Union 3D (3D Analyst)


Merges closed, overlapping multipatch features from an input feature class.


Union 3D


  • Closed multipatch geometry is required for this analysis. The Is Closed 3D tool can be used to determine if a multipatch feature class contains closed features, and the Enclose Multipatch tool can be used to eliminate gaps in multipatch features.

  • Multipatch features encompassing overlapping volumes are combined by intersecting the shells of the features and removing redundant interior portions. This process occurs iteratively until all multipatch features in the feature class have been processed.

  • A grouping field can be used to identify features to be unioned, such as when the multipatches represent building parts in a city where multiple features represent one building. This can significantly improve performance by reducing the number of times the tool must iterate through the dataset. Rather than comparing a feature against all features, it is only compared against those that participate in its group.

  • When optimization is enabled, the tool attempts to automatically subset the features into groups by analyzing the bounding box for each feature. Disabling optimization can increase the tool's performance if a grouping field has been specified. Optimization can also be disabled in the absence of a grouping field if the desired output is to union all overlapping features into a single multipatch.

  • Use caution when deciding how many features to aggregate, as very large and complex features may be created in the output feature class which may exhibit poor display performance.

  • A warning stating that the resulting feature is not simple and could not be created is raised if two or more multipatch features share only an edge or a vertex. The same message is returned if a group contains multipatches that share no volume or space.

  • An optional table can be created to identify the attributes of the source features that were unioned to create each unioned output.


arcpy.3d.Union3D(in_feature_class, out_feature_class, {group_field}, {disable_optimization}, {output_all}, {out_table})
ParameterExplanationData Type

The multipatch features that will be unioned.

Feature Layer

The output multipatch feature class that will store the aggregated features.

Feature Class

The field used to identify the features that should be grouped together.


Specifies whether optimization is performed or not performed on the input data. Optimization will preprocess the input data by grouping them to improve performance and create unique outputs for each set of overlapping features.

  • ENABLEOptimization is enabled, and the grouping field is ignored. This is the default. This is the default.
  • DISABLENo optimization is performed on the input data. Features will either be stored in a single output feature or be unioned according to their grouping field, if one is provided.

Determines if the output feature class contains all features or only the overlapping ones that were unioned.

  • ENABLEAll input features are written to the output. This is the default.
  • DISABLEOnly unioned features are written to the output. Non-overlapping features will be ignored.

A many-to-one table that identifies the input features that contribute to each output.


Code sample

Union3D example 1 (Python window)

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

import arcpy
from arcpy import env

env.workspace = 'C:/data'
arcpy.Union3D_3d('multipatch.shp', 'union_output.shp', 'GROUP_FIELD', 
                'DISABLE', 'ENABLE', 'UnionTable.dbf')
Union3D example 2 (stand-alone script)

The following sample demonstrates the use of this tool in a stand-alone Python script.

Name: Union3D Example
Description: This script demonstrates how to use the 
             Union3D tool.
# Import system modules
import arcpy

# Set environment settings
arcpy.env.workspace = 'C:/data'

# Set Local Variables
inMP = "multipatch.shp"

# Ensure output multipatch has a unique name
outMP = arcpy.CreateUniqueName("union_output.shp")
outTbl = arcpy.CreateUniqueName("UnionTable.dbf")
GroupField = "Type"
optimize = "DISABLE"
solids = "ENABLE"

# Execute Union3D
arcpy.ddd.Union3D(inMP, outMP, GroupField, optimize, solids, outTbl)

Licensing information

  • Basic: Requires 3D Analyst
  • Standard: Requires 3D Analyst
  • Advanced: Requires 3D Analyst

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