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.\" RCSid $Id: gensdaymtx.1,v 1.16 2022/08/13 17:24:56 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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] |
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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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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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irradiance values, total cloud cover, and broadband aerosol optical depth, one time step per line. |
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Such file can be generated by |
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.I epw2wea |
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with appending |
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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 adapted from gendaymtx |
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.SH "SEE ALSO" |
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dctimestep(1), genBSDF(1), gendaylit(1), gendaymtx(1), gensky(1), genskyvec(1), |
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rcollate(1), rcomb(1), rcontrib(1), rfluxmtx(1), xform(1) |