Clip Grid by Polygon

On the Grid tab, in the Utility group: Click Clip Grid by Polygon to clip a grid by a set of polygons. (Ctrl+G,C)

Input Data

Select the Source of the polygons used to clip the selected grids:

Selection	Design elements you have interactively selected in the Design Window.
Visible	Design elements that are visible in the loaded layer. Elements that have been specifically hidden are excluded. This a quick way of selecting all visible elements in a layer without having to explicitly select them.
Layer	One or more layers that you select. Names of layers currently loaded in the Design Window are shown in bold.

Plane Selection

Choose a plane source. Note that this will be used as the clipping plane.

Plan	Use Plan View (looking top down).
Camera	Use the current Camera view.

* The current plane of the view in the Design Window is not changed.

Settings

Select the Grids (layers) to be clipped by the input polygons

Select a Clip Mode or accept the default:

Keep Inside	Keep the grid points that fall inside the polygons and discard the outside points. This is the default.
Keep Outside	Keep the grid points that fall outside the polygons and discard the inside points.

Select the Show Hidden Points check box to ?

Apply

Finally, click Apply to clip the selected grids.

If necessary: On the Design tab, in the Action group, click Undo (CTRL + Z) and Redo (CTRL + Y) to undo and redo (revert the undo of) the last action.

To reduce memory usage and avoid out of memory exceptions when working with very large grids, the following settings are available in All Settings > Grid Triangulation