Data Clip Boundaries in Civil 3D

By Graham Riddleston 

I had an enquiry recently from a customer who was having problems with Data Clip boundaries in Civil 3D.

Their problem was that after creating a surface from a point file and adding a data clip boundary (to reduce the amount of data in the dwg) the chosen boundary didn’t appear to do anything.

The solution is to look at the order of the surface definitions. To do this, select the surface and go to Surface Properties then select the Definitions tab:

The way a surface is built is to apply all the definitions in the order they are displayed. So in the above case the entire contents of the csv file has been imported then the data clip boundary has been applied. This scenario won’t work because the data clip boundary is designed to restrict the amount data to import.

This can easily be rectified but using the arrow buttons on the left hand side of the panel to force the boundary to be defined first:

The two yellow shield symbols indicate that the surface is out of date but after a rebuild you will get the required result:

An alternative to avoid this situation arising is to add the boundary to the surface first then import the data file.