Hello all, I'm trying to clariy a couple of things about ALOS AVNIR2 scene orthorectification, 1. From the ENVI help someone can read : The along track incidence angle is the angle (in degrees) between the vertical position of the satellite and its forward or backward viewing direction. If viewed from the ground point corresponding to the scene center, the along track incidence angle has a positive value if the viewing direction is northward. The across track incidence angle is the angle (in degrees) between the vertical position of the satellite and its side-viewing direction when the sensor is scanning along the side. If viewed from the ground point corresponding to the scene center, the across track incidence angle has a positive value if the viewing direction is eastward. 2. While search for information a came along this piece o finfo : Optical Instrument Frequently Asked Questions (FAQ) Document Issue 1 Several angle values are embedded in ‘workreport’ file, how are they defined? Img_SunAngleElevation’ is the sun elevation, expressed as (90 - Img_SunAngleElevation) gives SZA. Img_SunAngleAzimuth’ is the sun azimuth positive from the north to east. Img_PointingAngle’, is the angle between viewing vector and vector pointing from platform to the satellite subtrack (nadir) (if negative, the pointing is toward the west). It is related to satellite zenith angle (VZA). Img_SceneCenterAngle’ is the angle between the vector pointing to satellite direction and local normal vector Img_SceneCenterOrientation’ looks to be the orientation of the satellite track with local meridian. If pointing is equal to 0, it is equal to the azimuth angle. No real information is given on azimuth angle 3. The scene I am working with includes this : (workreport file) Img_SceneCenterAngle="L0.2" Img_SceneCenterOrientation="13.6" Img_PointingAngle="0.000" Given the above, what values should be set in Incidence Along track and Across track angles, in ENVI's Build RPCs module? for the ALOS- AVNIR-2 image? Also, some suggestions for Polyonmial Orders (XS, YS, ZS, Omega, Phi and Kappa) values for the same data? Kind Regards,