The clipping planes option lets you view a specific area of an image by clipping the parts of the image that you do not want to view.
1. Click Clipping Planes icon 
in the 3D tab of the toolbar.
2. Click to mark the starting point of the clipping plane, move the cursor to the end point and click again.
The part of the volume from the line outward is deleted. You can draw more than one clipping plane and delete them separately.
Use the Screen Clipping Plane tool 
in the 3D tab of the toolbar to create a clipping plane that is always perpendicular to the current view.
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