Methods for best fit of curves

[[Me...]]

Hi, I have a question about Methods for best fit of curves.
Can someone tell me more about the theory than is in the instructions about method gaussian best fit and/or method tolerance band ? When is used which method ? Or some facts to the theory. I would be very thankful.

Here is the extract from the operating instructions:

Methods for best fit of curves
CALYPSO uses four best fit methods for curve measurement, whereby
the Chebyshev and L1 methods can be selected only for 2D:
– Gaussian best fit
With the Gaussian best fit (LSQ feature), the measured values are
translated and/or rotated until the sum of the error squares reaches
a minimum (certain degrees of freedom may be restricted here). This
operation leaves only the curve's form deviation.
Note: If the degrees of freedom are not restricted, the curve will be
rotated around the curve center of gravity. This usually corresponds
to a rotation around all coordinate axes. With a best fit with re-
stricted degrees of freedom, the result normally deviates from a best
fit around all axes as the curve is generally not located in a main
plane of the coordinate system. The greater the deviation, the far-
ther away the curve center of gravity is from the curve origin.
– Tolerance band
A Gaussian best fit is initially used for the best fit into the tolerance
band. Then the measurement points are moved further such that the
distances from the tolerance centers in the nominal normal direction
become minimal.

[[Cl...]]

This may give you some insight as to how this best-fit function might be used, (minus the GAUSS filter) I have two 2d curves
used in a freeform surface for evaluation as a surface profile. The part is cylindrical and lays along the X axis. On the right end
is a spherical cone and on the opposite end is the concentric primary datum (-A-) a vertical plane next to that is the secondary datum (-B-). The spherical cone needs to be within 0.1 to A & B. Because there is no clocking datum I locked rotation around of the two curves (Free from surface) around X.

[[Ma...]]

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Sorry, but here you are not locking axis but selecting axis which will be used for fitting - so you just selected to rotate around X axis.

But i wonder why i can not select Gauss or Tschebyscheff - when i do, profile of surface has wrong numbers ( i.e. 7 - depends on radius of tip )

[[SH...]]

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Can I ask what is the difference between opening and closing filter?.I never worked with freeform surface.

[[Cl...]]

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In my defense, this is the first time I've used the best-fit. I was on the phone with Zeiss support while I was doing this. He explained to me what exactly it was doing. I must have misunderstood what he was saying?

[[Ma...]]

What i know of using 2d/3d curve or free form bestfitting is, that if you select only one axis for rotate or translate and create alignment from it, then changes are only from selected axis.

[[Cl...]]

In this instance, no alignment was created as the profile was relative to two datum's.