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.\" RCSid $Id: gensdaymtx.1,v 1.3 2025/03/27 01:26:55 greg Exp $
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.TH GENSDAYMTX 1 01/19/13 RADIANCE
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.SH NAME
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gensdaymtx - generate an annual spectral sky matrix from a weather tape
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.SH SYNOPSIS
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.B gensdaymtx
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[
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.B "\-v"
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][
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.B "\-h"
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][
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.B "\-d|\-s"
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][
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.B "\-u"
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]][
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.B "\-r deg"
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][
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.B "\-m N"
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][
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.B "\-p Dir"
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][
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.B "\-n N"
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][
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.B "-o{f|d}"
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]
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[
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.B "tape.wea"
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or
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.B "tape.epw"
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]
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.SH DESCRIPTION
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.I Gensdaymtx
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takes a weather tape as input and produces a matrix of spectral sky patch
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values using the precomputed atmospheric scattering model.
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Unlike the similarly-named
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.I gendaymtx
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tool, the Perez sky model is not used.
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The weather tape is assumed to be in a special form of the .wea file, which contains
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a short header with the site parameters followed
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by the month, day, standard time, direct normal and diffuse horizontal
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illuminance values, total cloud cover, and broadband aerosol optical depth, one time step per line.
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Alternatively, a standard EPW (EnergyPlus Weather) file may be provided.
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Such file can be generated by
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.I epw2wea
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with the
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.I \-a
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flag.
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Each time step line is used to compute a column in the output matrix,
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where rows correspond to sky patch positions, starting with 0 for
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the ground and continuing to 145 for the zenith using the default
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.I "\-m 1"
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parameter setting.
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.PP
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.I Gensdaymtx
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uses the OPAC continental average aerosol profile for the Mie scattering calculation.
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For every distinct AOD value in the weather tape, a new set of the atmospheric parameters
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is computed and stored in the atmos_data directory in the current directory, which
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can be changed using the -p flag. This precomputation can be sped up using the
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.I \-n NThreads
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option. There is no speedup after NTHREADS=16.
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.PP
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Increasing the
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.I \-m
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parameter yields a higher resolution
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sky using the Reinhart patch subdivision.
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For example, setting
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.I "\-m 4"
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yields a sky with 2305 patches plus one patch for the ground.
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Each matrix entry is in fact 20 values, corresponding to
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spectra from 380nm to 730nm at 20nm interval (watts/sr/meter^2).
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Thus, an hourly weather tape for an entire year would
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yield 8760x20 (175200) values per output line (row).
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.PP
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The
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.I \-g
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option may be used to specify a ground color.
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The default value is
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.I "\-g 0.2"
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corresponding to a 20% gray.
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.PP
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If there is a sun in the description,
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.I gensdaymtx
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will include its contribution in the four nearest sky patches,
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distributing energy according to centroid proximity.
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The
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.I \-d
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option may be used to produce a sun-only matrix, with no sky contributions,
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and the ground patch also set to zero.
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Alternatively, the
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.I \-s
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option may be used to exclude any direct solar component from the output,
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with the other sky and ground patches unaffected.
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.PP
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The
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.I \-u
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option ignores input times when the sun is below the horizon.
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.PP
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By default,
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.I gensdaymtx
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assumes the positive Y-axis points north such that the first sky patch
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is in the Y-axis direction on the horizon, the second patch is just
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west of that, and so on spiraling around to the final patch near the zenith.
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The
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.I \-r
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(or
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.I \-rz)
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option rotates the sky the specified number of degrees counter-clockwise
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about the zenith, i.e., west of north.
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This is in keeping with the effect of passing the output of
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.I gensky(1)
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or
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.I gendaylit(1)
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through
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.I xform(1)
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using a similar transform.
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.PP
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The
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.I \-of
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or
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.I \-od
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option may be used to specify binary float or double output, respectively.
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This is much faster to write and to read, and is therefore preferred on
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systems that support it.
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(MS Windows is not one of them.)\0
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The
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.I \-h
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option prevents the output of the usual header information.
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Finally, the
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.I \-v
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option will enable verbose reporting, which is mostly useful for
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finding out how many time steps are actually in the weather tape.
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.SH EXAMPLES
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Produce an annual spectral sky matrix without solar direct:
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.IP "" .2i
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epw2wea Detroit.epw Detroit.wea -a;
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gensdaymtx -m 1 -s Detroit.wea > Detroit.mtx
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.PP
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Produce an hourly, annual Reinhart sky matrix
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with 2306 patches including solar contributions
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and send float output to
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.I dctimestep(1)
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to compute a sensor value matrix:
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.IP "" .2i
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gensdaymtx -m 4 -of VancouverBC.wea | dctimestep -if -n 8760 DCoef.mtx > res.dat
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.SH AUTHORS
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Taoning Wang
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.SH "SEE ALSO"
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dctimestep(1), epw2wea(1),
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genBSDF(1), gendaylit(1), gendaymtx(1), gensky(1), genskyvec(1), genssky(1),
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pvsum(1), rcollate(1), rcomb(1), rcontrib(1), rfluxmtx(1), rmtxop(1), xform(1)
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