Union

Applicability:

• Cadcorp SIS Map Modeller
• Cadcorp SIS Map Editor
• Cadcorp SIS ActiveX Modeller

Ribbon Group:

Analysis-Boolean Operations

Conditions for use:

• Item Class: LineString / Polygon
• Minimum number selected: 2
• Minimum item status: Editable

Associated commands:

• Dissolve
• Intersect
• Subtract
• Symmetric Difference

Description:

 Union replaces selected items with an item containing combined geometry.

Example:

1. Select the source items (two or more).
   
   
   
   
2. Select Union.
   
   
3. If the selected items do not have different attributes the new item containing combined geometry will now be created.

If any of the selected items do have different attributes, the Select item to keep dialog is displayed to prompt you for which item’s attributes you want to keep. When the items are merged, only the attributes belonging to the chosen item are kept.

In the above example this would be:

Click on Previous and Next to switch between items.

Note: If you do not want the Select item to keep dialog to be displayed every time you snap onto overlying items uncheck the Automatic tickbox.

4. Click OK in the dialog showing the item you wish to keep, in this example item 3 (Cabbage) is chosen, the following combined geometry will be created:

Note: If you are using the Union command with LineStrings and you want to end up with a LineString Item, rather than a MultiLineString Item, use the Join Linestrings [CAD-Alter] command with an Exact Tolerance value of 0.

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