LAS to POD File Compression

Question

Does anyone have more info on these compression figures? (see image below) Is there a way to have no compression? What does "Automatic" mean? Why do we have POD files in the first place? Ha. 
 
 Thank you.

Dan Weston · Answer

MicroStation describes their intent in the Point Cloud Help chapter: Sets the maximum allowable loss of accuracy in meters during compression. A higher number means more compression. 
 
 And from the Pointools Users Guide: 
 
 Compression 
 POD files compress cloud data for efficient storage and faster retrieval from disk. You can set the accuracy you wish to maintain. It is important to consider the accuracy of the instrument used to acquire the data and to not set the compression accuracy too high. If the required accuracy cannot be achieved the data will not be compressed 
 
 Compression sets the desired accuracy of the points and allows efficient point storage within the POD file. If, for example you have an aerial LIDAR dataset with accuracy of +/- 10cm setting the compression to 1mm would be unnecessary. Instead it should be set to 10cm. For terrestrial LIDAR, 1cm is usually sufficient for general purpose use. 
 --- 
 These questions will generate more response from the Descartes and Pointools Forum; moving the post there.