Trend surface

You can use the gaussian fitting process with 3D data to put a trend surface through a set of spot-height values.

This can be a useful way to visualise a landscape given a series of discrete altitude values. Contours are drawn at the Z-tickmarks if style ‘contour’ is set, and if style ‘riser’ is selected, the risers are drawn from the surface rather than from the XY-plane.