GSRou

Hello, I am trying to understand what all is out there in terms of applying atmospheric corrections (i.e. calculating atmospheric transmittance and downwelling thermal radiance) to Thermal Infrared remotely sensed data. I know that ENVI has corrections for the TIMS Scanner. I also know that Landsat 8 higher level products have corrections through the Landsat Surface Reflectance Code (LaSRC). However, I am more interested in trying to find solutions not necessarily from satellite based thermal imagery but from airborne (and to a lesser extent) UAV based platforms. Are there methods that can determine these parameters on these two platforms? The most popular method is with MODTRAN, but it is quite expensive, and I wish to find other alternatives that more cost-effective.