compamb - compute good ambient value for a rad input file
compamb [ -c ][ -e ] rad_input_file
Compamb computes a good ambient value for the specified rad(1) variable file and appends it to the file as a "render= -av" option. If the -c option is specified, then compamb includes color information in the computed ambient value, rather than estimating a grey value to avoid rendering color shifts. If the -e option is specified, then compamb also computes a good exposure value for this scene, and appends it to the rad file as well.
Compamb is a shell script that makes calls to other RADIANCE programs and utilities to do the actual work. A substantial amount of time may be required to complete this script, since compamb calls rpict(1) to render low resolution frames for each view in the rad file, setting "QUALITY=High" to compute interreflections. The resulting ambient file is thrown away, since it would disagree with the new -av setting used for the final renderings. This method is preferable to setting the -aw option of rpict, which frequently results in splotchy artifacts.
Greg Ward Larson
lookamb(1), rad(1), rpict(1)