I am working with MODIS Terra (and simultaneous ASTER) Level 1B swath data using ENVI and am having one of these "this should be easy" questions about the most direct way to get to geo-referenced datasets of radiances (and reflectances). There are two ways I'm familiar in reading in this data:
- If I download the HDF L1B swath datasets they come as files named MOD021KM.Ayyyyddd.[whatever].hdf containing scaled integers, with the scaling factors in the header. The geolocation information is in separate files MOD03.Ayyyydd.[whatever].hdf, which I have as well. ENVI is able to convert the scaled integers into radiances, but not to apply the geolocation (to effectively turn this into a Lat/Long projecton). So I'm currently stumped with this approach.
- Alternatively, I can download my swaths band-by-band as GeoTIFF from the NASA LAADSWEB site, which combines the relevant MOD021KM and MOD03 files. I read them into ENVI and stack the bands I need. But then I still need to convert the data into radiances/reflectances, which requires me to download the HDF file as well and search around in the header for the correct coefficients.
Right now I'm doing 2. But is there a way of going down the path of 1? ENVI's "Geolocate MODIS" function stumps me -- it seems there's something for L3 data and L1A data, but nothing for L1B.