Overlay!
By Ehsan Hamzei 810392121
Type of Overlay
• Intersection
• Union
• Erase
• Identity
• Symmetrical Difference
• Update
Intersect
• Computes a geometric intersection of the input features.
Features or portions of features which overlap in all
layers and/or feature classes will be written to the output
feature class.
Union
• Computes a geometric union of the input features. All
features and their attributes will be written to the output
feature class.
Erase
• Creates a feature class by overlaying the Input Features
with the polygons of the Erase Features. Only those
portions of the input features falling outside the erase
features outside boundaries are copied to the output
feature class.
Identity
• Computes a geometric intersection of the input features
and identity features. The input features or portions
thereof that overlap identity features will get the
attributes of those identity features.
Symmetrical Difference
• Features or portions of features in the input and update
features that do not overlap will be written to the output
feature class.
Update
• Computes a geometric intersection of the Input Features
and Update Features. The attributes and geometry of the
input features are updated by the update features in the
output feature class.
References
• ESRI Arc GIS Help…
Thanks

Arc GIS Overlay Functions

  • 1.
  • 2.
    Type of Overlay •Intersection • Union • Erase • Identity • Symmetrical Difference • Update
  • 3.
    Intersect • Computes ageometric intersection of the input features. Features or portions of features which overlap in all layers and/or feature classes will be written to the output feature class.
  • 4.
    Union • Computes ageometric union of the input features. All features and their attributes will be written to the output feature class.
  • 5.
    Erase • Creates afeature class by overlaying the Input Features with the polygons of the Erase Features. Only those portions of the input features falling outside the erase features outside boundaries are copied to the output feature class.
  • 6.
    Identity • Computes ageometric intersection of the input features and identity features. The input features or portions thereof that overlap identity features will get the attributes of those identity features.
  • 7.
    Symmetrical Difference • Featuresor portions of features in the input and update features that do not overlap will be written to the output feature class.
  • 8.
    Update • Computes ageometric intersection of the Input Features and Update Features. The attributes and geometry of the input features are updated by the update features in the output feature class.
  • 9.
  • 10.