To use the Best Fit Analyser dialog

Use the Best Fit Analyser dialog to calculate the Best Fit and view the results.

To run a Best Fit item:

  1. Right-click the Best Fit item in the inspection sequence and select Play item from the context menu. The Best Fit Analyser dialog displays:
    • the method you selected in the Edit Best Fit Definition dialog.
    • the mean distance from the nominal and the standard deviation for the groups you selected.
    • a graph showing the distance of each point from the nominal. Click to change the scale of the graph's Y axis.
  2. In the Maximum iteration box, enter the number of fitting calculations to be performed each time you click Go Step.
  3. In the Threshold box, enter a cut-off distance. If the movement between successive calculations is smaller than this distance for all points, the analysis stops. If you enter a distance of less than 0.0001, the value is converted to exponential notation when you click Go Step.
  4. By default, the analysis uses all points in the selected groups. To exclude outlying points from the calculations, select the Use filter check box and move the sliders to identify the points to be used.

    In this example, only points in the range +0.1 to +0.5 are used in the best-fit calculation.

  5. Click Go Step. The analyser performs the number of calculations specified in the Maximum iteration box and updates the dialog:
    • Calculation information displays the current mean and standard deviations of the points, and the rotation and translation used to achieve this result.
    • Previous step results displays the mean and standard deviation of the points before this step.
    • The graph displays the updated deviations as a red line. For example:

  6. Repeat step 5 to refine the fit, or click OK to accept the result and close the dialog.
  7. To display information about the Best Fit, click the Info tab.

    This example shows that the selected alignment was:

    • rotated about the X axis by 0.097 degrees.
    • rotated about the Y axis by -0.330 degrees.
    • rotated about the Z axis by 0.464 degrees.
    • translated by an X of 0.405, Y of -1.580 and Z of -0.785.
Parent topic: To create a Best Fit alignment