The make_adb utility has several command line options that allow the user to learn about how the utility has been configured and which allow the user to control the atmospheric modeling. If you run the make_adb utility without any arguments or with the -help you will get the following output:
prompt> make_adb
Build Date: Aug 28 2003 08:40:46
usage: make_adb [options] <CFG file>
where [options] are:
-help Print this help/usage message
-use_config <file> Use alternate configuration info
-config Print configuration info
-standard Run in standard mode
-fast_sky Use a single MODTRAN run for the sky dome
-fascode_sky Use FASCODE for downwelled sky dome
-max_inversion <alt> Set the max inversion altitude
-max_range <range> Set the max range for sensor paths
The Build Date: is a useful piece of information that can allow you to compare the age of your version of the make_adb utility with the most recent version.
The -use_config option allows the user to specify an alternate configuration file for make_adb which will be used instead of the configuration file in the $DIRSIG_HOME/config directory. This is a useful option is a user wants to use make_adb with a different version of MODTRAN or FASCODE
The -config option will print out the configuration defined by the either the default or user-supplied configuration file. Running the command with this option also performs a few basic configuration tests. For the configuration file shown above, the output of this option would be:
MODTRAN is configured
MODTRAN executable path = /usr/local/mod4r01/mod4r01.exe
MODTRAN Data directory path = /usr/local/mod4r01/DATA
MODTRAN minimum frequency delta = 1
MODTRAN output log filename = modtran.log
FASCODE is configured
FASCODE executable path = /usr/local/fascode-3.0/fascode.exe
FASCODE PRT11 executable path = /usr/local/fascode-3.0/prt11.exe
FASCODE tape3 directory path = /usr/local/fascode-3.0/tape3
FASCODE output log filename = fascode.log
FASCODE maximum frequency = 3500
Background radiance file = /use/local/dirsig/lib/data/misc/star_light.dat
The -fast_sky option instructs make_adb to use a single MODTRAN run to estimate the sky radiance. This is a not a good approximation of the downwelled sky radiance, but it does allow the make_adb utility to run much faster which may be useful when you are initially setting up a simulation.
Do not use this option to create production imagery.
Under normal operation, make_adb only uses FASCODE for the paths from the sensor to the scene. All the other path radiances and transmissions are extrapolated from MODTRAN runs at the MODTRAN maximum resolution. The -fascode_sky option instructs make_adb to use FASCODE for all the sky radiances. Enabling this option will dramatically increase the total run time for make_adb but when the sky is viewed by the sensor this option should always be used.
This option is only relevant when you are modeling a system that has a spectral resolution higher than the MODTRAN limit.
If the template tape5 supplied to make_adb contains radiosonde data (or what MODTRAN refers to as a "user-defined atmosphere"), then make_adb attempts to correct the boundary layer temperature of the atmospheric profile so that it matches the temperature in the weather file for the current simulation time. This process involves attempting to interpolate the air temperatures from the ground to an inversion layer in the supplied atmospheric profile. This inversion layer is automatically found by identifying changes in the slope of the air temperature. If you know what altitude the inversion layer is at, this value can be supplied with the -max_inversion option. To avoid any inversion adjustments, supply a -max_inversion value of 0.0.
This option is only relevant when your template tape5 contains a "user-defined atmosphere".
If your simulation entails a sensor with a "up-looking" or "forward-looking" view then the -max_range option will need to be used. This option controls how make_adb will create the sensor-to-target path radiance and transmission commands by defining the maximum range that a target will be viewed. This constrains the interpolation and extrapolation of the path radiances and transmissions to different ranges to reasonable limits to minimize interpolation and extrapolation errors. The value supplied with this argument is in kilometers and should be chosen based on scene knowledge. For example, if you are looking up at a factory stack from 1 km away, the value supplied with the -max_range should be 1.0.
This option is only relevant when you are modeling an "up-looking" or "forward-looking" sensor.