As the user starts to reverse engineer their part.  Sometimes it is important to look at how closely that CAD deviates from the original scan data.  This can help a user make sure the part is with-in tolerance of the project guidelines.  XTract3D has a tool that colormaps the difference between the CAD and the scan data.  The slider can be tweaked so that users can see where they are missing material and where there is too much present.  Here is a video demonstrating that: