man/man1/gendaymtx.1

.\" RCSid $Id: gendaymtx.1,v 1.19 2025/02/26 20:39:28 greg Exp $
.TH GENDAYMTX 1 01/19/13 RADIANCE
.SH NAME
gendaymtx - generate an annual Perez sky matrix from a weather tape
.SH SYNOPSIS
.B gendaymtx
[
.B "\-v"
][
.B "\-h"
][
.B "\-A"
][
.B "\-d|\-s|\-n"
][
.B "\-u"
][
.B "\-D sunfile"
[
.B "\-M sunmods"
]][
.B "\-r deg"
][
.B "\-m N"
][
.B "\-g r g b"
][
.B "\-c r g b"
][
.B "-o{f|d}"
][
.B "\-O{0|1}"
][
.B "\-i intvl"
]
[
.B "tape.wea"
or
.B "tape.epw"
]
.SH DESCRIPTION
.I Gendaymtx
takes a weather tape as input and produces a matrix of sky patch
values using the Perez all-weather model.
The weather tape may be in the simple ASCII format understood
by DAYSIM, which contains a short header with the site parameters followed
by the month, day, standard time, direct normal and diffuse horizontal
irradiance values, one time step per line.
Alternatively, a standard EPW (Energy Plus Weather) input may be provided,
in which case additional information such as the dew point temperature may
be used in the calculation.
Each time step line is used to compute a column in the output matrix,
where rows correspond to sky patch positions, starting with 0 for
the ground and continuing to 145 for the zenith using the default
.I "\-m 1"
parameter setting.
.PP
Increasing the
.I \-m
parameter yields a higher resolution
sky using the Reinhart patch subdivision.
For example, setting
.I "\-m 4"
yields a sky with 2305 patches plus one patch for the ground.
Each matrix entry is in fact three values, corresponding to
red green and blue radiance channels (watts/sr/meter^2).
Thus, an hourly weather tape for an entire year would
yield 8760x3 (26280) values per output line (row).
.PP
The
.I \-A
option tells
.I gendaymtx
to generate a single column corresponding to an average sky
computed over all the input time steps, rather than one
column per time step.
.PP
The
.I \-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
.I "\-c 0.960 1.004 1.118".
Similarly, the
.I \-g
option may be used to specify a ground color.
The default value is
.I "\-g 0.2 0.2 0.2"
corresponding to a 20% gray.
.PP
If there is a sun in the description,
.I gendaymtx
will include its contribution in the four nearest sky patches,
distributing energy according to centroid proximity.
The
.I \-d
option may be used to produce a sun-only matrix, with no sky contributions,
and the ground patch also set to zero.
Alternatively, the
.I \-s
option may be used to exclude any direct solar component from the output,
with the other sky and ground patches unaffected.
.PP
The
.I \-u
option ignores input times when the sun is below the horizon.
This is a convenient way to average daylight hours only with the
.I \-A
option or to ensure that matrix entries correspond to solar positions
produced with the
.I \-D
option, described below.
.PP
The
.I \-n
option may be used if no matrix output is desired at all.
This may be used to merely check the input, or in combination with the
.I \-D
option, below.
.PP
The
.I \-D
option may be used to specify an output file to contain a list of
solar positions and intensities corresponding to time steps in the
weather tape where the sun has any portion above the horizon.
Sun radiance values may be zero if the direct amount is zero on the input.
Sun modifiers and names will be indexed by the minute, numbered from
midnight, January 1st.
If a hyphen ('-') is given as the argument to
.I \-D,
then the sun descriptions  will be directed to the standard output.
This implies the
.I \-n
option just described.
If the
.I \-M
option is given as well, it will be used to record the modifier
names used in the
.I \-D
output, for convenient input to
.I rcontrib(1).
.PP
By default,
.I gendaymtx
assumes the positive Y-axis points north such that the first sky patch
is in the Y-axis direction on the horizon, the second patch is just
west of that, and so on spiraling around to the final patch near the zenith.
The
.I \-r
(or
.I \-rz)
option rotates the sky the specified number of degrees counter-clockwise
about the zenith, i.e., west of north.
This is in keeping with the effect of passing the output of
.I gensky(1)
or
.I gendaylit(1)
through
.I xform(1)
using a similar transform.
.PP
The
.I \-i
option specifies the actual capture interval in minutes of the original
weather data.
Please see the man page for
.I gendaylit
to understand this correction, which is applied only near sunrise and
sunset.
.PP
The
.I \-of
or
.I \-od
option may be used to specify binary float or double output, respectively.
This is much faster to write and to read, and is therefore preferred on
systems that support it.
(MS Windows is not one of them.)\0
The
.I \-O1
option specifies that output should be total solar radiance rather
than visible radiance.
The
.I \-h
option prevents the output of the usual header information.
Finally, the
.I \-v
option will enable verbose reporting, which is mostly useful for
finding out how many time steps are actually in the weather tape.
.SH EXAMPLES
Produce an uncolored Tregenza sky matrix without solar direct:
.IP "" .2i
gendaymtx -m 1 -c 1 1 1 -s Detroit.wea > Detroit.mtx
.PP
Produce an hourly, annual Reinhart sky matrix
with 2306 patches including solar contributions
and send float output to
.I dctimestep(1)
to compute a sensor value matrix:
.IP "" .2i
gendaymtx -m 4 -of VancouverBC.wea | dctimestep -if -n 8760 DCoef.mtx > res.dat
.SH AUTHORS
Ian Ashdown wrote most of the code,
based on Jean-Jacques Delaunay's original gendaylit(1) implementation.
Greg Ward wrote the final parameter parsing and weather tape conversion.
.SH "SEE ALSO"
dctimestep(1), genBSDF(1), gendaylit(1), gensdaymtx(1), gensky(1),
genskyvec(1), genssky(1),
rcollate(1), rcontrib(1), rfluxmtx(1), rmtxop(1), rxfluxmtx(1), xform(1)
Revision:	1.20
Committed:	Thu Oct 23 23:34:59 2025 UTC (11 days, 7 hours ago) by greg
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.19:	+3 -5 lines
Log Message:	docs: Added rxfluxmtx man page and updated others accordingly
#	Content
1	.\" RCSid $Id: gendaymtx.1,v 1.19 2025/02/26 20:39:28 greg Exp $
2	.TH GENDAYMTX 1 01/19/13 RADIANCE
3	.SH NAME
4	gendaymtx - generate an annual Perez sky matrix from a weather tape
5	.SH SYNOPSIS
6	.B gendaymtx
7	[
8	.B "\-v"
9	][
10	.B "\-h"
11	][
12	.B "\-A"
13	][
14	.B "\-d\|\-s\|\-n"
15	][
16	.B "\-u"
17	][
18	.B "\-D sunfile"
19	[
20	.B "\-M sunmods"
21	]][
22	.B "\-r deg"
23	][
24	.B "\-m N"
25	][
26	.B "\-g r g b"
27	][
28	.B "\-c r g b"
29	][
30	.B "-o{f\|d}"
31	][
32	.B "\-O{0\|1}"
33	][
34	.B "\-i intvl"
35	]
36	[
37	.B "tape.wea"
38	or
39	.B "tape.epw"
40	]
41	.SH DESCRIPTION
42	.I Gendaymtx
43	takes a weather tape as input and produces a matrix of sky patch
44	values using the Perez all-weather model.
45	The weather tape may be in the simple ASCII format understood
46	by DAYSIM, which contains a short header with the site parameters followed
47	by the month, day, standard time, direct normal and diffuse horizontal
48	irradiance values, one time step per line.
49	Alternatively, a standard EPW (Energy Plus Weather) input may be provided,
50	in which case additional information such as the dew point temperature may
51	be used in the calculation.
52	Each time step line is used to compute a column in the output matrix,
53	where rows correspond to sky patch positions, starting with 0 for
54	the ground and continuing to 145 for the zenith using the default
55	.I "\-m 1"
56	parameter setting.
57	.PP
58	Increasing the
59	.I \-m
60	parameter yields a higher resolution
61	sky using the Reinhart patch subdivision.
62	For example, setting
63	.I "\-m 4"
64	yields a sky with 2305 patches plus one patch for the ground.
65	Each matrix entry is in fact three values, corresponding to
66	red green and blue radiance channels (watts/sr/meter^2).
67	Thus, an hourly weather tape for an entire year would
68	yield 8760x3 (26280) values per output line (row).
69	.PP
70	The
71	.I \-A
72	option tells
73	.I gendaymtx
74	to generate a single column corresponding to an average sky
75	computed over all the input time steps, rather than one
76	column per time step.
77	.PP
78	The
79	.I \-c
80	option may be used to specify a color for the sky.
81	The gray value should equal 1 for proper energy balance.
82	The default sky color is
83	.I "\-c 0.960 1.004 1.118".
84	Similarly, the
85	.I \-g
86	option may be used to specify a ground color.
87	The default value is
88	.I "\-g 0.2 0.2 0.2"
89	corresponding to a 20% gray.
90	.PP
91	If there is a sun in the description,
92	.I gendaymtx
93	will include its contribution in the four nearest sky patches,
94	distributing energy according to centroid proximity.
95	The
96	.I \-d
97	option may be used to produce a sun-only matrix, with no sky contributions,
98	and the ground patch also set to zero.
99	Alternatively, the
100	.I \-s
101	option may be used to exclude any direct solar component from the output,
102	with the other sky and ground patches unaffected.
103	.PP
104	The
105	.I \-u
106	option ignores input times when the sun is below the horizon.
107	This is a convenient way to average daylight hours only with the
108	.I \-A
109	option or to ensure that matrix entries correspond to solar positions
110	produced with the
111	.I \-D
112	option, described below.
113	.PP
114	The
115	.I \-n
116	option may be used if no matrix output is desired at all.
117	This may be used to merely check the input, or in combination with the
118	.I \-D
119	option, below.
120	.PP
121	The
122	.I \-D
123	option may be used to specify an output file to contain a list of
124	solar positions and intensities corresponding to time steps in the
125	weather tape where the sun has any portion above the horizon.
126	Sun radiance values may be zero if the direct amount is zero on the input.
127	Sun modifiers and names will be indexed by the minute, numbered from
128	midnight, January 1st.
129	If a hyphen ('-') is given as the argument to
130	.I \-D,
131	then the sun descriptions will be directed to the standard output.
132	This implies the
133	.I \-n
134	option just described.
135	If the
136	.I \-M
137	option is given as well, it will be used to record the modifier
138	names used in the
139	.I \-D
140	output, for convenient input to
141	.I rcontrib(1).
142	.PP
143	By default,
144	.I gendaymtx
145	assumes the positive Y-axis points north such that the first sky patch
146	is in the Y-axis direction on the horizon, the second patch is just
147	west of that, and so on spiraling around to the final patch near the zenith.
148	The
149	.I \-r
150	(or
151	.I \-rz)
152	option rotates the sky the specified number of degrees counter-clockwise
153	about the zenith, i.e., west of north.
154	This is in keeping with the effect of passing the output of
155	.I gensky(1)
156	or
157	.I gendaylit(1)
158	through
159	.I xform(1)
160	using a similar transform.
161	.PP
162	The
163	.I \-i
164	option specifies the actual capture interval in minutes of the original
165	weather data.
166	Please see the man page for
167	.I gendaylit
168	to understand this correction, which is applied only near sunrise and
169	sunset.
170	.PP
171	The
172	.I \-of
173	or
174	.I \-od
175	option may be used to specify binary float or double output, respectively.
176	This is much faster to write and to read, and is therefore preferred on
177	systems that support it.
178	(MS Windows is not one of them.)\0
179	The
180	.I \-O1
181	option specifies that output should be total solar radiance rather
182	than visible radiance.
183	The
184	.I \-h
185	option prevents the output of the usual header information.
186	Finally, the
187	.I \-v
188	option will enable verbose reporting, which is mostly useful for
189	finding out how many time steps are actually in the weather tape.
190	.SH EXAMPLES
191	Produce an uncolored Tregenza sky matrix without solar direct:
192	.IP "" .2i
193	gendaymtx -m 1 -c 1 1 1 -s Detroit.wea > Detroit.mtx
194	.PP
195	Produce an hourly, annual Reinhart sky matrix
196	with 2306 patches including solar contributions
197	and send float output to
198	.I dctimestep(1)
199	to compute a sensor value matrix:
200	.IP "" .2i
201	gendaymtx -m 4 -of VancouverBC.wea \| dctimestep -if -n 8760 DCoef.mtx > res.dat
202	.SH AUTHORS
203	Ian Ashdown wrote most of the code,
204	based on Jean-Jacques Delaunay's original gendaylit(1) implementation.
205	Greg Ward wrote the final parameter parsing and weather tape conversion.
206	.SH "SEE ALSO"
207	dctimestep(1), genBSDF(1), gendaylit(1), gensdaymtx(1), gensky(1),
208	genskyvec(1), genssky(1),
209	rcollate(1), rcontrib(1), rfluxmtx(1), rmtxop(1), rxfluxmtx(1), xform(1)