The best fit takes place in three steps:• Gaussian best fit of the actual points to the respective nominalpoints.• Calculation of the perpendicular leg points of the best fit nominalpoints on the CAD model.• Gauss best fit of the actual points to the respective perpendicularleg points.The 3D best fit assumes that the part in the vicinity of the nominal points isflat.This is usually an acceptable approximationWith “ Best Fit to CAD model“, the curvature of the model in the vicinity of thenominal points is taken into consideration