By Polygons – 12D Wiki Beta Test

Null Triangles – Outside of a Polygon

This option is used to Null (remove) any Triangle whose centroid is outside a selected polygon. Continue down the page to see the Null Triangles Outside Polygon options. To Null Triangles Outside Polygon, Use: Tins => Null => Null After a TIN has been created, it can be edited at any time and one of [...]

Null by Polygons

If you are used to nulling triangles by drafting a freehand rectangle on the screen, then you might be stumped by the new ‘Null Triangles by Polygon’ panel. The default pick method is the pink arrow, which will let you choose an existing polygon. But it’s a hassle to draft the rectangle first, then to [...]