Hi all, My problem is how to project AMSR-E Sea Ice Concentration product(http://www.iup.uni-bremen...ygrid_swath/n6250/). This product has a hdf format, and I save it as a ENVI standard format. According to readme file of this product, its projection is "NSIDC Sea Ice Polar Stereographic North", whose datum is D_Hughes_1980 supported by the projection engine. So, I add "Hughes_1980, 6378273.0, 6356889.449" to the end of ellipse.txt, "D_Hughes_1980, Hughes_1980," to the end of datum.txt, and "D_Hughes_1980, D_HUGHES_1980" to the end of datum_overrides.txt. However, the datum "D_Hughes_1980" doesnot show when I define the projection. Also, I donot know how to define map projection for this product in ENVI. In addition, I try to solve this problem in ArcGIS. I define the project of this product(ENVI standard format) with "NSIDC Sea Ice Polar Stereographic North" using ArcGIS sucessfully. When I project a shapefile data (WGS 84) to match this product in order to subset this product, the programme require me to select geographic transformation. However, in the list there is no option of "WGS 84 to D_Hughes_1980". It seems that it is impossible to project other spatial data to match the AMSR-E Sea Ice Concentration product. I wonder if anyone could help me. Thank you! Long MA