Constructing a Best Fit or Best Fit Recompensate Sphere

You can construct a "best fit" sphere using five or more features. 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 sphere, one for which PC-DMIS minimizes the average squared distance from the data points to the sphere.

To construct a Best Fit or a Best Fit Recompensate Sphere:

  1. Open the Construct Sphere dialog box (Insert | Feature | Constructed | Sphere).

  2. From the Method list, select either the Best Fit or Best Fit Recompensate option (shown as Best Fit and BF Recomp ).

  3. From the Feature list, select five or more features.

  4. Select the In or Out option. For details, see the "In / Out Sphere" topic in this documentation.

  5. from the Best Fit Type list, select the type of best fit algorithm to use. For details, see the "Best Fit Type (for Sphere)" topic in this documentation.

For Best Fit (BF) or Best Fit Recompensate (BFRE) constructions, while you can use any feature type for your input features, BF and BFRE fit types are typically used with point features or point sets (a scan of points, a feature set with points, or an expression that resolves to an array of points).

For Best Fit Recompensate, one of the five features must be a point.

  1. 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.

  2. Click the Create button.

For a Best Fit constructed sphere, the Edit window command line would read:

CONSTR/SPHERE,BF,feat_1,feat_2,feat_3,feat_4,feat_5...

PC-DMIS uses the actual measured points for construction.

For a Best Fit Recompensate constructed sphere, the Edit window command line would read:

CONSTR/SPHERE,BFRE,feat_1,feat_2,feat_3,feat_4,feat_5...

PC-DMIS uses the center of the probe for measurement.


A - Best Fit Sphere Constructed from Five Points.

Constructing a Sphere from Five or more Points