Common: The geometric correction process consists of three steps. The first step is an off-line process from Level-1 data product generation to prepare geometric parameters such as the line-of-sight vectors of detectors and the pointing axes information. These parameters are effective for a long time, depending on the instrument stability, and are recorded in the geometric correction data base files.

The second step is an on-line process executed during Level-1 product generation to identify the observing points of detectors, using the geometric parameters available in the geometric correction data base files and the engineering information supplied by the instrument and the spacecraft. This process is called "Geometric System Correction".

The third step is also an on-line process to enhance band-to-band registration accuracy by image matching techniques. This step consists of two parts. One is the SWIR parallax correction process. Another is the inter-telescope registration process.

Generation of Geometric Correction Data Base: The geometric correction data base files contain the line-of-sight vectors of the detectors, the pointing axis vectors and the conversion coefficients from encoder values to angles. The line-of-sight vectors of the detectors and the pointing axis vectors were evaluated toward the Navigation Base Reference of the spacecraft during the preflight test period using the collimator data and the alignment data on the spacecraft.

These geometric parameters will be corrected after launch through the validation activity using GCPs (Ground Control Points) and band-to-band image matching techniques.