Interpolate X,Y

Use the Coordinates > Interpolate X,Y menu option (XYFILL2 GX) to replace all dummies in X/Y channels by linear, cubic spline or maximum entropy prediction interpolation.

Interpolate X,Y dialog options

X channel

Select the X channel to interpolate.

Script Parameter: XYFILL2.XCH

Y channel

Select the Y channel to interpolate.

Script Parameter: XYFILL2.XCH

Fill method

Select the interpolation method: 

  • "Linear" interpolates gaps linearly between neighbors.
  • "Minimum Curvature" uses a minimum curvature interpolation. This produces the smoothest line, but the interpolation may be unstable if the data is noisy.
  • "Akima" is also a smooth interpolation, but it is more stable in the presence of noise.
  • "Prediction" uses a maximum entropy prediction algorithm to predict the missing values such that they will have noise characteristics similar to the original data.

Script Parameter: XYFILL2.METHOD

Fill dummy edges?

Choose "Yes" to interpolate dummies beyond the edges of the data.

Script Parameter: XYFILL2.EDGE

Application Notes

The XYFILL2 GX can be useful for replacing missing locations in coordinate data. Both Minimum curvature and Akima interpolation methods define a second-order cubic spline to interpolate dummy values. Minimum curvature produces the smoothest possible interpolation but may cause undesirable overshoot in some areas, whereas Akima interpolation tends to be less smooth but does not suffer from excessive overshoot. Prediction applies a maximum entropy prediction algorithm to estimate missing values with similar noise characteristics. Useful for FFT filtering. You can enforce continuity and periodicity at line ends. Linear is a standard straight-line interpolation between points. Nearest assigns the value of the nearest non-dummy point.

The XYFILL2.GX interpolates new X and Y values based on the fiducial channel only.

See Also: