I retrieve AOD from MOD04 based on MCTK. But the resolution of output is random when use geographic coordinate system. I wonder if I could get geographical output with a certain resolution without resampling or resizing the output. I use 'out_ps = [0.03d,0.03d] ;' in my IDL pro, but it doesn't work for MOD04 is not the grid dataset. And I kown I can get the output with 10km resolution when I choose the projected coordinate system. However, I prefer the output with geographic coordinate system and a cerain spatial resolution. My part code is as following: ... output_projection = envi_proj_create(/geographic) out_ps = [0.03d,0.03d] ; convert_modis_data, in_file=modis_swath_file, $ out_path=output_location, out_root=output_rootname, $ swt_name=swath_name, sd_names=sd_names, $ out_method=out_method, out_proj=output_projection, $ interp_method=interpolation_method, /no_msg,$ background=-999,fill_replace_value=-999, $ r_fid_array=r_fid_array, r_fname_array=r_fname_array, $ bridges=bridges, msg=msg .... Thanks for your kind instuction. Regrads, Qingqing