Tools > Alignment > Best Fit Alignment (does not apply to point objects) changes the coordinates of one object to match the other using a best-fit algorithm.
This function operates in two phases:
the initial gross alignment phase, in which the objects are aligned only roughly using a lower number of points of comparison. Initial gross alignment can be bypassed if the user know the objects are already in rough alignment.
the fine adjustment phase, in which alignment is optimized using a higher number of points of comparison.
The Fixed object is the one that is pre-selected in the Model Manager.
Setup group - sets basic parameters that affect the speed of the process.
Object Name dropdown - (list contains the name of every object in the Model Manager) specifies which object is considered to be the Float.
Disable display checkbox - specifies whether to save system resources by eliminating real-time update of the Viewing Area during alignment.
Sample Size field (default 300) - specifies the number of points on the surface of each object that will be compared during the alignment process. A lower number may give faster but less precise alignment. Typically, accept the default. If you accept the default, a second alignment is performed using a value of 1500.
Tolerance field (decimal; not applicable when Fine Adjustments Only is checked) - specifies a degree of allowable error during an exhaustive symmetry check. Typically, accept the default.
Probe Radius field (decimal; default 0; use non-zero value only when the Test data was collected with a spherical hard probe or laser tracking ball, or if all test data is known to be offset by a known distance) - specifies the offset distance of all test data.
Thoroughness group - affects the precision (and computation time) of the alignment process.
Check Symmetry (Exhaustive) checkbox - specifies whether to perform initial gross alignment more exhaustively. This is useful for symmetric objects for which rough alignment might be achieved in several ways but for which there is an optimal rough alignment that must be detected exhaustively.
Fine Adjustments Only checkbox - specifies whether to skip the initial gross alignment phase, useful when you assume the object to be close to correct alignment already.
Automatic Deviator Elimination checkbox - automatically calculate the defective points that must be ignored during the alignment.
Statistics group - presents details about the most recent alignment.
Model Max. Length - indicates the greatest distance that any point moved during the alignment.
Avg. Error - indicates the average deviation of all points of comparison. The smaller the value, the more precise the alignment.
Deviator Elimination group (applicable when Automatic Deviator Elimination is OFF; available after Apply is pressed the first time) - During the first alignment, every point on the Float is assigned an “error” value that represents the distance of its final position from its original position. If the first alignment is imperfect, use this slider to eliminate the higher deviators or the lower deviators from the next alignment process, then press Apply again. Alignment will be performed again, but with some points of the Float being ignored. The alignment might be better than the previous attempt.
Slider and Error indicator - controls the degree to which deviant points on the Float are ignored during the next alignment. When Error is 0, relatively few points (those that were found to be perfect during the first alignment) are used in the next alignment. If no points were found to be perfect, the next alignment will not execute at all. If Slider is set to the maximum error, all points on the Float are considered during the next alignment (and the next alignment will give the same result as the previous).
Reverse Selection checkbox - toggles the effect of the Slider. The next alignment will be based on low deviators rather than high ones, or on high deviators rather than low ones.
OK button - saves the reoriented Float object and closes the dialog.
Cancel button - closes the dialog without saving a modified Float object.
Apply button - performs exhaustive symmetry check (if requested), initial gross alignment (unless Fine Adjustments Only is checked), then fine adjustment, and leaves the dialog open for further fine-tuning of the alignment. If it is necessary to fine-tune the alignment, you will typically check Fine Adjustments Only, set the Sample Size greater than the default 1500, and press Apply again.