You can construct a "best fit" ellipse from three or more features. The ellipse lies in the current workplane. The best fit construction method takes the actual measured points, rather than the ball's center (as is the case of best fit recompensate). In both cases, PC-DMIS computes a least squares ellipse, one for which PC-DMIS minimizes the average squared distance from the data points to the ellipse.
To construct a Best Fit Ellipse or a Best Fit Recompensate Ellipse:
Open the Construct Ellipse dialog box (Insert | Feature | Constructed | Ellipse).
From the Method list, select either the Best Fit or Best Fit Recompensate option (shown as Best Fit and BF Recomp).
From the Feature list, select at least four features or a scan or a set comprised of at least four points.
Select the In or Out option. For details, see the "In / Out Ellipse" topic in this documentation.
Select the 2D or 3D option. For details, see the "2D / 3D Ellipse" topic in this documentation.
Select the Remove outliers check box if you want to remove outliers based on the distance from the best fit feature. For details, see the "Remove Outliers / Standard Deviation Multiple for a Constructed Ellipse" topic in this documentation.
If you want to change the feature theoretical values, select the Feature theoreticals check box and type in the values. For details, see the "Specifying Feature Theoreticals" topic in the PC-DMIS Core documentation.
Click the Create button.
The Edit window command line for this option would
read:
CONSTR/ELLIPSE,BF,feat_1,feat_2,feat_3...
(Uses the actual measured points for construction.)
or
CONSTR/ELLIPSE,BFRE,feat_1,feat_2,feat_3...
(Uses the center of probe for measurement.)
More:
Remove Outliers / Standard Deviation Multiple for a Constructed Ellipse