genskyvec - compute patch radiance averages for a specific sky
genskyvec [ -m N ][ -c r g b ]
Genskyvec samples the Radinace sky description given on the standard
input to generate a list of average patch radiances. If there is a sun
in the description, genskyvec will include its contribution in the
three nearest sky patches, distributing energy according to centroid
By default, genskyvec divides the sky into 2305 patches, plus one patch
for the ground. This corresponds to Reinhart’s extension of the
Tregenza sky, where the original 145 patches are subdivided into 16
subpatches, except at the zenith. A different subdivision may be
specified via the -m option. The value given will be used to subdivide
each dimension, so the default of 4 yields almost 16 times as many
patches as the original Tregenza sky, which can be specified with -m 1.
A higher resolution sky is generally better for daylight coefficient
analysis where solar position is important.
The -c option may be used to specify a color for the sky. The gray
value should equal 1 for proper energy balance The default sky color is
-c 0.960 1.004 1.118 .
To generate 578 patches corresponding to a 2x2 subdivision of the
Tregenza sky on a sunny equinox noon:
gensky 9 21 12 | genskyvec -m 2 > sky09_21_12.dat
dctimestep(1), gensky(1), gentregvec(1), rtcontrib(1), rtrace(1)