International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B3. Istanbul 2004
Figure 3 Warped Imge using Wavelet Modulus Maxima
absolute value and location indicates the rotation and scale. A
new image constructed by applying the rotation and scale and it
is created by using bilinear interpolation. Once again by finding
the phase correlation ratio of the newly generated image with
the reference image, shift between the images are identified.
The maximum absolute value of the Inverse FFT of this ratio
provides the shifts in both x and y directions. After deriving all
Figure 4 Simulated Image to be warped using FFT
the three parameters of translation, rotation and scale, the input
image is warped by taking care of all the three errors
simultaneously, to avoid multiple re-sampling of the image. To
test this algorithm an IRS PAN images of different dates are
“simulated” for rotation of 9 degrees, translation in X is 12
and in Y is —10 pixels. Due to the same sensors data scale
factor is same. This algorithm could identify the shifts exactly
but only the rotation is identified as 9.09 degrees instead of 9
Figure 5 Log — Polar image of simulated image
degrees. When the rectified image is swiped on the reference
image it could be observed easily for its well registration.
Figure 6 shows the rectified image.
Figure 6 Warped Image using FFT
4.5 MORPHOLOGICAL PYRAMID APPROACH
The MPIR technique minimizes the SSE between two images
based on the intensity for matching, since registration methods
based on initial intensity values can make effective use of all
data available. This technique uses an optimization scheme of
coarse-to-fine iterative refinement strategy over the MP pair
(Zhongxiu Hu, 2000). Based on the matching criteria,
convergence indication can be obtained. Once convergence has
been achieved at a particular pyramid level a transition to finer
level is made. The solution from the previous pyramid level is
used as an initial estimate. The new incremental estimate is
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