Trimming and Breaking Objects

At one point or another, we are all faced with the tedious prospect of breaking or trimming a lot of drawing objects on different layers.  TheMAP > TOOLS menu offers two great utilities to make these tasks easier: Boundary Trim and Boundary Break.  The dialog boxes that control these two tools are very similar.


This tutorial shows how Boundary Trim works. Simply substitute the word “trim” with “break”, and most of the following information applies to the Boundary Break dialog box, as well. The Trim dialog box has four sections: Boundary, Objects to Trim, Trim Method and Objects That Cannot be Trimmed.

The Boundary section controls what object is used to determine which objects are trimmed and where they are trimmed. You can select an object in the drawing (a closed polyline or circle), or you can define a closed polyline by picking the vertices.

The Objects to Trim section controls what gets trimmed. You can select objects manually, by picking them on screen, or you can use powerful filtering tools to automatically select objects on certain layers.

The Trim Method section controls how the objects are trimmed, either inside or outside the trim boundary. You can also choose whether to ignore objects which have topology data and/or whether to retain data attached to objects after they are trimmed.

The Objects That Cannot be Trimmed section controls how MAP treats objects like text, which cannot be trimmed. You can choose whether to ignore such objects that intersect the trim boundary, delete them, or to delete them only if their insertion points are inside (or outside) the trim boundary.

Anyone who has used AutoCAD’s standard trim or break commands on large groups of objects can immediately see the value of this tool, particularly when you need to be selective about which objects are trimmed.  The tool is particularly useful for dividing very large datasets into individual “tiles”, such as a city-wide drawing into individual files for a map grid.

The Boundary Break version is very useful for tasks where you need to retain the portions of objects that are trimmed, such as contour lines within building footprints.

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