GAMMA Questions

Dear Gamma Users,

I have faced some difficulty understanding how Gamma calculates the scene centre Lat/Lon and heading angle (as in *.slc.par). Actually, these metadata are left blank in ALOS-1 SLC Leader file. According to the FacilityRelatedDataRecord of leader file, the Record sequence number 17 (Bytes 1025-2024) seems to contain coefficients, a0,a1,..a24 and b0,b1,...,b24 of the 8th polynomial expression to convert from (pixel, line) to (latitude, longitude). I have calculated scene centre Lat/Lon using the same formula but this is not the same as the value calculated by Gamma. Also, I have no clue about how the heading angle is calculated. Any help regarding this matter would be greatly appreciated.

Thanks and regards
Kaushik