Select the Inverse Distance Weighting gridding method from the Gridding window and then click <More Options> to open a window. The upper left-hand corner of the window contains power and smoothing parameters, which are specific to the inverse distance weighting algorithm.
Enter a value in the Power to the distancetext box in the upper left-hand corner of the window to specify a weighting factor. The larger the power, the less effect data points far from a grid node have during interpolation. The smaller the power, the more evenly distributed the weighting is over neighboring input data values.
For example, at a power of 5 the grid node value approaches the value of the nearest input data point. At a power of 0, all data input values are given the same weight, resulting in a highly smoothed grid. The default power setting of 2 provides acceptable results for most datasets.
Enter a value in the Smoothing factor text box in the upper left-hand corner of the window. This smoothing factor will help minimize the bulls-eye effect, characteristic of this algorithm. A value of 4 results in a high degree of smoothing, while 2 results in a more moderate degree of smoothing. 0 is the default. The greater the smoothing factor, the less closely your grid node values will match input data points.
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