The Strength calculation represents the relative stiffness of the cloud-to-cloud registration with respect to the six degrees of freedom (x,y,z).
As always Strength, C2C, and target error values are used together with visual inspection to determine the quality of any registration. A low strength value does not necessarily mean a bad registration, only that the values are of Strength are out of balance.
The calculation is now based upon how evenly distributed the x,y, and z transformation and rotations are accounted for in the point clouds in the overlap area. Values are now listed in a hover event over the Strength box in the right-side panel. The main value shown is the lowest out of the three values.
The highest Strength return is set at 100% and the other axis (usually x or y) are shown as a percentage of the strongest or 100%. Usually, the Z value has the highest value because of the floor (ground) and the ceiling, if inside.
The biggest change seen will be with scans performed inside. The Z value will be derived from both the floor and ceiling while the X and Y will be from walls. Depending on the number of walls the strength value can be low as the balance of the strength is in the Z while the X and or Y might be very low. While this overall value is low (the value shown in the strength box) the hover event is useful as it shows the percentage balance of each axis.