Warping surfaces to match control points

[brad.nelson(at)nrc.ca (Brad Nelson)]

I purchased a magnetic field grid which was generated from poor
navigation data. When we flew through the area again and measured the
magnetic field, many of the anomalies were displaced by km.  Does
anyone have an IDL procedure for warping an existing image (my grid
data) to a set of control points (my flight measurements). All of the
warping programs that I have seen rely on two images and a few "this
pixel should be over here" control points.  Nowhere have I found an
algorithm that takes many points and matches features.  Any
suggestions?