AVNIR-2 Products Information

ALOS-1 products follow the standard CEOS format convention. The detailed product format specifications were defined and maintained by JAXA.

Level	Definition	Option	Note
1A	Uncompressed, reconstructed digital counts appended with radiometric calibration coefficients and geometric correction coefficients (appended but not applied)		Separate image files for each band
1B1	Radiometrically calibrated data at sensor input		Separate image files for each band
1B2	The following correction options are available: R: Geo-reference data; G: Geo-corded data; D: Rough DEM (Digital Elevation Model) correction: this option corrects the topographical influence to the areas where DEM was covered. DEM correction is effective only in Japanese region. There is a possibility that DEM correction error will occur when pointing angle is large. In this case, accuracy is not guaranteed because interpolation is carried out in the error area. If specifying this option outside the Japanese region, D option becomes effective, however, DEM applied product is not generated. That is; the product, which is defined as altitude = 0m, will be generated.	Map-Projection: UTM, Polar Stereographic	Separate image files for each band

NB : Level 0 is not available for use

AVNIR-2 Product Characteristics

Level 1A is not calibrated
A summary file (ASCII file) is provided with all data processed. This ASCII file embeds basic information on product metadata.
Pixel spacing, to be applied for transformation from level 1B1 to level 1B2, is strongly dependent on the pointing angle of the AVNIR-2 instrument when observing the area of interest. This parameter is fixed by the processor based on the following pointing angles:

Pointing angle	0 to 31.6 degrees	Angle 31.6 to 40.3 degrees	More than 40.3 degrees
Pixel spacing (m)	10	15	20

Radiometric rescaling gain and offset values for each band are expressed in W/m2strm and can be retrieved from products processed into CEOS format. These values are stored in the scene header record. It should be noted that the processing chain applies a pre-flight calibration and the coefficients have been determined before launch. No in-flight calibration was applied.
Solar spectral irradiance values are not provided with the products processed into CEOS format. They can be computed using the following values (Thuillier 2003):

Band	Band 1	Band 2	Band 3	Band 4
Central Wavelength (nm) (m)	463	560	652.1	820.6
Solar spectral irradiance (W/m2/_m)	1943.3	1813.7	1562.3	1076.5

For the projection parameter, users can choose between UTM or Polar Stereographic. The projection parameters are fixed by the processor. The Polar stereographic parameter corresponds to the latitude/longitude of the scene centre.
Rational Polynomial Coefficients (RPC) are not provided with the product format. If users want to apply map projection; to transform geo referenced product to geo coded product, they need to use the polynomial coefficients provided with the CEOS format.