The PolyWorks methodology consists in managing the point clouds by using grid cells uniformly distributed along the XY plane. As all the points cannot be kept in physical memory simultaneously, incoming point cloud files are read scan by scan, and points are relocated into their respective cells and written back to disk. Once all points have been imported, users can access specific areas to perform measurements or feature extraction by enabling or disabling grid cells. To prevent physical memory exhaustion, PolyWorks offers a grid cell manager that indicates to users how much RAM they will use when they enable N grid cells.
More information on PolyWorks huge dataset feature can be found on InnovMetric's website at http://www.innovmetric.com/Surveying/english/whats_new.html.
Source: Innovmetric, Dec. 20, 2004