ENVI Classic definitely does support AVNIR-2 imagery. You can open it using File > Open External File > ALOS > AVNIR-2. In FLAASH, "Ground Elevation" means the elevation of the ground surface. It is looking for a representative elevation for the image as a whole. It doesn't have to be a precise average elevation for the image. Just an elevation that occurs in the image area, to give a general sense for the elevation of the study area. If you are finding it difficult to come up with all of the parameters needed to run FLAASH, you might want to try QUACC. It gives comparable results, and doesn't require that you set as many parameters. - Peg Exelis VIS