Fit Weights
Double-clicking a point in the list will bring up the Best-Fit Item dialog.
This dialog provides another way to remove the point from the fit (Use in Fit), and conveniently allows you to change the reference point’s coordinates, as well as the per-component fit weight for the point. The 1 and 0 buttons are simply shortcuts for set- ting the corresponding fit weight value.
Fit weights give you control over defining whether a certain component of a point has any influence in the fit process. A value of zero indicates that the component has no influence in the fit, whereas a value of 1 indicates the component has full influence. Any intermediate value may be chosen. If a component is weighted to zero, it is displayed in gray in the point list. If an intermediate value is chosen, it is displayed in blue, and if the weight is set to 1, it is displayed in black.
One reason for reducing the weight of a specific component of a point is to reduce directional errors. Suppose you have a measured point that was performed on a floor that was flexing in the z-direction during measurement. It is reasonable to assume that the measured point has significant error in the z direction when compared to the x or y direction, therefore reducing the weight of the z component may be a wise choice. Another reason is when using discrete points to control specific degrees of freedom, an advanced technique that, while do- able using best-fit, is much easier to perform using relationship fits.
You’ll notice that you have a significant amount of control in the fit. Access to changing the fit parameters is provided via the controls in the upper-left hand corner of the dialog.