isofit.radiative_transfer.modtran

class ModtranRT(engine_config, full_config)

Bases: isofit.radiative_transfer.look_up_tables.TabularRT

A model of photon transport including the atmosphere.

find_basedir(config)

Seek out a modtran base directory.

load_tp6(infile)

Load a ‘.tp6’ file. This contains the solar geometry. We Return cosine of mean solar zenith.

load_chn(infile, coszen)

Load a ‘.chn’ output file and parse critical coefficient vectors.

These are:

• wl - wavelength vector
• sol_irr - solar irradiance
• sphalb - spherical sky albedo at surface

• transm - diffuse and direct irradiance along the

  sun-ground-sensor path

• transup - transmission along the ground-sensor path only

Be careful with these! They are to be used only by the modtran_tir functions because MODTRAN must be run with a reflectivity of 1 for them to be used in the RTM defined in radiative_transfer.py.

• thermal_upwelling - atmospheric path radiance

• thermal_downwelling - sky-integrated thermal path radiance

  reflected off the ground and back into the sensor.

We parse them one wavelength at a time.

ext550_to_vis(ext550)

.

modtran_driver(overrides)

Write a MODTRAN 6.0 input file.

build_lut(rebuild=False)

Each LUT is associated with a source directory.

We build a lookup table by:

1. defining the LUT dimensions, state vector names, and the grid of values;
2. running modtran if needed, with each MODTRAN run defining a different point in the LUT; and
3. loading the LUTs, one per key atmospheric coefficient vector, into memory as VectorInterpolator objects.

rebuild_cmd(point, fn)

.

required_results_exist(fn)

load_rt(fn)

.

get(x_RT, geom)

get_L_atm(x_RT, geom)

get_L_atm_vswir(x_RT, geom)

get_L_atm_tir(x_RT, geom)

get_L_down_transmitted(x_RT, geom)

get_L_down_transmitted_vswir(x_RT, geom)

get_L_down_transmitted_tir(x_RT, geom)

thermal_downwelling already includes the transmission factor. Also assume there is no multiple scattering for TIR.

wl2flt(wls, fwhms, outfile)

Helper function to generate Gaussian distributions around the center wavelengths.