Edit/view surfaces - Delete triangles with centroid inside polygon

[gvdpeor]

In order to perform this command is it necessary to plot tins? Sometimes it is very hard to select the trim border under all those tins.

[Lars]

Yes, this command is often used to create holes in a surface. You can create a polyline, drape it on to the surface and then triangulate all your input data plus your draped polyline (draped line as breakline). The draped polyline clips triangels and makes it possible to delete all triangles inside the polyline.