A Best Fit alignment is an alignment that causes a set of measured points or a set of actual feature centroids to match, as closely as possible to its nominal location or theoretical counterpart. In certain cases, it is also possible for a Best Fit alignment to optimally match a set of points to a CAD curve or surface.
To understand the different Best Fit Alignment methods, see "The Best Fit Alignment Methods".
About Exclusions
For 2D Vector Best Fit Alignments - Features with vector directions that are perpendicular to the 2D best-fit plane are excluded from the alignment calculation.
For All Best Fit Alignments - Features that are skipped during measurement routine execution are excluded from the alignment calculation.
If all features of the alignment are excluded, PC-DMIS displays an error message. If this occurs during execution, PC-DMIS pauses the execution and gives you the option of canceling execution. You can check the Best Fit Alignment dialog box (Insert | Alignment | New | Best Fit button) to see if any of the alignment's features were excluded due to invalid vectors or because they were skipped during execution.
More:
The Best Fit Alignment Methods
2D Best Fit Command Line Format
3D Best Fit Command Line Format
Constraints for Best Fit Alignments
Constructed Feature Sets and Curves as Best Fit Alignment Inputs
Scans as Best Fit Alignment Inputs