Model for Trend

Select how you wish to treat trends in your data by selecting one of five options under Data Trend Treatment near the bottom of the Kernel Gridding window.

$image\Trend_No.gif$ No action on trend – The input data is gridded without applying a model for trend treatment. The trend is assumed to be a flat plane.

$image\Trend_Mean.gif$ Mean value of input data – Use this option when you wish to extract residuals without applying a trend. The residuals will be represented as the difference from the mean of the input data.

$image\Trend_1st.gif$ 2D 1st-order polynomial – Fits a 2D 1st-order polynomial (y = a + bx) to the input data, which is appropriate if the trend has one predominant dip direction. This is the default.

$image\Trend_2nd.gif$ 2D 2nd-order polynomial – Fits a 2D 2nd-order polynomial (y = a + bx + cx2) to the input data, which is appropriate if the trend has two predominant dip directions.

$image\Trend_3rd.gif$ 2D 3rd-order polynomial – Fits a 2D 3rd-order polynomial (y = a + bx + cx2 + dx3) to the input data, which is appropriate if the trend has more than two predominant dip directions.

If the Action on Trend is set to Default, then WinPICS uses the 2D 1st-order polynomial as the trend model. If the Action on Trend is set to Grid raw input, then No Action on trend is the trend model. treatment.