A ClearanceCube is a three-dimensional virtual box that you define in PC-DMIS. It's purpose is to act as an invisible protective envelope that surrounds your part and its fixture. During measurement routine execution, PC-DMIS uses the faces of the ClearanceCube as safe pathways for your probe to travel to avoid collisions with your part.
Sample ClearanceCube Surrounding the CAD Model
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ClearanceCube Definition - Size tab