Global Image Composite of ADEOS/OCTS GAC Data
The
OCTS products contain the satellite position and
velocity in ECR. But, the satellite movement can
be also expressed using the distance between the
Earth center and the satellite center (R), the
longitude of ascending node(O), the inclination(i), the latitude argument from ascending node on the orbital plane(u) as follows (Hashimoto, T., 1998).
Both ( P
s, V
s ) and (R, O, i, u) are time dependent. The variation ratios of the former are bigger than those of the latter, especially at the equator or the Polar Regions. So the latter is suitable for the expression of satellite movement. In this work, the parameters for satellite movement and attitude are expressed by the polynomials of line number (L) as ;
The coefficients of polynomials for (R, O, i, u) and attitude are determined by the regression analysis using the navigation data.
The view vector and the observed ground point (X, Y, Z) satisfy the collinearity equations as follows (Hashimoto, T., 1997).
In
the equation (4), the parameters (R, O, i, u) and
(
w,
f,
k
) are treated as exterior orientation parameters.
Sufficient numbers of GCPs are necessary for exterior orientation. Conventionally, the GCP has been collected by human interpretation. Such procedure is very time consuming and not proper for daily process. In this work, the GCP collection is realized automatically by the image matching technique. The matching was done using two kinds of templates; one from the Generic Mapping Tool (GMT) coastal data (Wessel, P., 1999) prepared in advance, another from the original image which was binarized to make coast line data. The position of templates was selected as a GCP candidate from the GCP library. The precise navigation data are determined using the GCPs. A rectified image is generated using the newly determined navigation data.
