🛠️ Identity

Purpose: > The output of Identity has the extent and all the features of input layer, with the geometry and attributes merged in the area where input and identity layer overlaps. At the places of overlaps, Input layer features will get the attributes of Identity layer.

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🎭 Illustration

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📋 Technical Specifications

Requirement	Detail
Input Feature Types	Any
Output Feature Type	Same or lesser dimension
Map Name	04.Intersect
inputs GDB	04.input_intersect.geodatabase
output GDB	04.output_intersect.geodatabase

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🧠 Logic & Arithmetic Operation

Logic: $(A - B ) \cup (A \cap B)$

⚙️ Parameters & Conditions

Input Parameter: Input Features

Overlay Parameter: identity Features

Geometry: Any

No. of Inputs: Two or more

Order: Doesn’t matter $A \cap B = B \cap A$

Coordinate System: Same as 1st input layer

⚙️ Identity Tool: Parameters and Combinations

🔧 Parameters

• Input Features
  • Geometry: Can be Point, Line, or Polygon
  • Input and Identity layers can be the same or different
• Identity Features
  • Must be either Polygon geometry or the same geometry type as the input
  • Defines the identity layer for overlay
  • Output layer always has the same geometry type as the input

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🔗 Input and Identity Combinations

Valid combinations (Format: Input, Identity):

1. (Point, Point)
2. (Line, Line)
3. (Polygon, Polygon)
4. (Point, Polygon)
5. (Line, Polygon)

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🚩 Important Notes

• Unlike Union or Intersect, Identity is not commutative:

\[A \; \text{Identity} \; B \neq B \; \text{Identity} \; A\]

• For combinations with different geometries (4 and 5), output is not possible.
• For combinations with the same geometry type, results differ depending on the extent of the layers.
• This gives us eight possible scenarios to consider when starting experiments.

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🐍 Arcpy Function

arcpy.analysis.Identity(in_features, identity_features, out_feature_class, {join_attributes}, {cluster_tolerance}, {relationship})

for more on function parameters, check: Arcpy Documentation Here.

🖼️ Figures

🖼️ Same Input with different Order

🟢 Point

Inputs	Output AB	Output BA

🟢 Line

Inputs	Output AB	Output BA

🟢 Polygon

Inputs	Output AB	Output BA

🟢 different Inputs

Input-Identity	Input	Output
Point-Polygon
Line-Polygon

🎨 Symbology Note

Output features may vary in colour and appearance depending on the attribute symbology used in the Identity tool. This highlights changes in features and attributes of the input layer.