operation, the kernel size is reduced to 4 samples by 8 lines,
and a polynomial interpolation on the resulting correlation
matrix provides a fractional value for the lag position. This
is the final match position.
The relative height (DH) of a feature on the landscape is
then derived by the relationship:
DH ¼ DX=tan/; ð2Þ
where DX is the parallax, or final match offset, and / is the
intersection angle. As the image matching method uses a
‘‘kernel’’ operation, the exact parallax at any point is not
calculated, but instead an average parallax for the kernel is
derived, and the resulting calculated values of height are
essentially smoothed.1 The resulting ASTER DEMs of
Taranaki and Ruapehu (Fig. 3) were georeferenced initially