Union replaces selected items with an item containing combined geometry.

Select Analysis > Boolean Operations > Union.


  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.
  4. 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.
  1. 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 prefer a final LineString Item rather than a MultiLineString Item, use the Join Linestrings (CAD > Alter) command with an Exact Tolerance value of 0.