International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B1. Istanbul 2004 
  
  
Figure 1 Optics of GLI Sensor in the Satellite Coordinates 
ER E¥RERD 4 * gp um us885u 
s 
  
  
  
ILLE LITT 
CUI = x a 
DGF in 
Figure 2 Example of Detectors on Focal Plane (250m, Ikm) 
  
  
  
  
  
  
  
  
  
  
focal channel No. 
plane |km 250m 
VNI 1-9 20, 21 
VN2 10 — 19 22.23 
SWI 24 — 27 
SW2 28, 29 
MT 30 — 36 
  
  
Table 2 Channels of GLI 
In this work, the ECR (Earth Centred Rotating) coordinates are 
used as the object coordinate system. The view vector in the 
satellite coordinates can be related with the observed object on 
the ECR coordinates by the following collinearity equations. 
  
RY Ía a aXX, 
| 2 
R, esa d t fr (2) 
R (a, a, ag ZZ, 
a, a, az) 
a, à. a, l= PP! (3) 
a, a, Hs 
R. 
Fzb-—p fc 
AR, (4) 
R 
  
where (Xo, Yo, Zo)= satellite position 
(X, Y, Z )=object Coordinates in ECR coordinates 
P — transformation matrix from satellite coordinates 
to ECR coordinates 
The matrix P at any time is determined by the satellite motion 
and attitude. The products of the GLI contain the position and 
velocity in the ECI (Earth Centred Inertial) coordinates as well 
as the attitude of every scan. 
2. CORRECTION PROCEDURE 
2. GCP Extraction 
The correction procedure is conducted utilizing a Ground 
Control Point (GCP). The GCPs are extracted automatically by 
the template matching as shown in Figure 1. About 1,000 GCP 
candidates are selected from the capes or islands all over the 
world and stored in the library. As the coastal data base, the 
GSHHS (Global Self-consistent, Hierarchical, High-resolution 
Shoreline database) prepared by Univ. of Hawaii are used 
(Wessel, 1999). The matching procedure can be done with sub- 
pixel unit. In this works, the size of 1/4 pixel was adopted. 
Besides of the pair of object coordinates and image coordinates 
of each GCP, the GCP data set contains the errors derived by 
the subtraction of estimated image coordinates (L, P.) from 
actual image coordinates (L, P). The GCP data sets are made by 
different process levels (or different parameters) as shown in 
Table 3. Although most of the GCPs are from the non-tilt 
operation, some GCPs are from the tilt operation. 
  
  
  
  
  
| GCP lib. | | coastal data | LIA image 
| L/O flag on L1À image coord. | image chip 
  
    
   
  
matching 
   
  
Correlation 
Es > "es 9 
coefficient threshold 
    
Figure 3 Automatic GCP Extraction 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
; remarks 
res. | name | level No. channels 
Ql a 678 | 23 
Q2 b 231 all 
Boe 1719 | all 
Q4 d 2034 | all 
K1 a 3418 | 19,24,26,30,34,35,36 
1km K2 b 13574 | all (except 31, 32, 33) 
K3 d 12499 | all (except 31, 32, 33) 
  
*) a: just after launch 
b: after correction of Sat/GLI alignment 
c: after modification of detector address 
d: after all corrections 
Table 3 GCP Data Sets