Image Analysis, Classification and Change Detection in Remote Sensing, 3rd Edition

Image–image registration 219

FIGURE 5.34

Closed contours der ived from the 3N band of an ASTER imag e over Nevada

acquired in July 200 3.

where b

1

= a

1

and b

i

= q

i

. T he integer q

i

satisfies (q

i

−a

i

) mod 8 = 0 and |q

i

−

b

i−1

| → min, i = 2, 3 . . . n.

∗

They also suggest applying the smoothing filter

{0.1, 0.2, 0.4, 0.2, 0.1} to the result. After both processing steps, two chain

codes can be easily compared by “sliding” one over the other and determining

their maximum correlation. The closed contours a re further characterized by

determining their first four Hu moments h

1

. . . h

4

, Equations (5.14).

∗

This is rather cryptic, so here is an example: For the wraparound ...