man/man1/evalglare.1

.\" RCSid $Id: evalglare.1,v 1.1 2015/08/12 23:07:59 greg Exp $
.TH EVALGLARE 1 7/30/15 RADIANCE
.SH NAME
evalglare \- determines and evaluates glare sources within a 180 degree fisheye HDR image
.SH SYNOPSIS
.PP
.nh
.B evalglare 
[ 
.BI \-s 
] 
[ 
.BI \-y 
] 
[ 
.BI \-Y \ value 
] 
[ 
.BI \-B " angle"
] 
[ 
.BI \-b " factor"
] 
[ 
.BI \-c " checkfile"
]
[ 
.BI \-t " xpos ypos angle"
] 
[ 
.BI \-T " xpos ypos angle"
] 
[ \-d ] 
[ 
.BI \-r " angle"
] 
[ 
.BI \-i " Ev"
] 
[
.BI \-I " Ev yfill_max y_fill_min" 
] 
[ 
.BI \-v 
] 
[ 
.BI \-V 
] 
[ 
.BI \-g " type"
] 
[ 
.BI \-G " type"
] 
[ 
.BI \-u " r g b"
] 
[ 
.BI \-vf " viewfile"
] 
[ 
.BI \-vt t  
] 
[ 
.BI \-vv " vertangle"
] 
[ 
.BI \-vh " horzangle"
] 
.RI [ hdrfile ]
.hy
.SH DESCRIPTION
.PP
.B Evalglare
determines and evaluates glare sources within a 180 degree fisheye
image, given in the RADIANCE image format (.pic or .hdr). If
.I hdrfile
is not given as an argument, the standard input is read.  The image
should be rendered as fisheye (e.g.  using the
.BI \-vt a 
or 
.BI \-vt h 
option) using 180 degrees for the horizontal and vertical view angle
.RB ( -vv
.IR 180 ,
.B -vh
.IR 180 ).
The recommended size of images input to 
.B evalglare
is 1000x1000 pixels; the computations become very long when the image
is more than 1200x1200 pixels.
.PP
The calculation of glare proceeds in two steps:
.IP 1. 3em
In the first step, the program uses a given threshold
to determine all glare sources.  Three different threshold methods are
implemented.  The recommended method is to define a task area by
.B \-t 
or 
.B \-T 
option.  The average luminance of the task area is calculated.  Each
pixel exceeding this value multiplied by the
.B \-b 
factor, default 5, is treated as a potential glare source.  The other
two methods are described below, see
.BR \-b .
.IP 2.
In the second step, the program tries to merge glare source pixels to
one glare source, when they are placed nearby each other.  This
merging is performed between search areas, given by an opening angle
.BR \-r ,
default 0.2 radians.  If a check file is written,
.B \-c
.IR fname ,
the detected glare sources will be colored, each with a different
color, and the rest of the image will be set to gray.  The luminance values
of all pixels are kept to the initial value.  The color is chosen by
chance, no significance is given by the color.  To enable unform
coloring of all glare sources, the
.B \-u 
option can be used.  Luminance
peaks can be extracted to separate glare sources by using the 
.B \-y 
or
.BI \-Y " value"
option.  The default value 
.B \-y
is 50,000 cd/m2, which can be changed by using the 
.B \-Y 
value.  A smoothing option,
.BR \-s , 
counts initial non-glare source pixels to glare sources, when they are
surrounded by a glare source.
.PP
The program calculates the daylight glare probability (DGP) as well as
other glare indices (DGI, UGR, VCP, CGI) and writes them to the
standard output.  The DGP describes the fraction of persons disturbed
caused by glare from daylight as a number from 0 to 1, where 0 is
no-one disturbed and 1 is everyone.  Values lower than 0.2 are out of
the range of the user assessment tests which the program is based on
and should be interpreted carefully.  A low light correction is
applied to the DGP when the vertical illumiance is lower than 500 lux.
By the use of
.B \-g
or 
.B \-G
.\" Citation?
the field of view is cut according the the definition of Guth.
The option 
.B \-B 
angle (in radians) calculates the average luminance of a
horizontal band.  In the case of non-180 degree images, an external
measured illuminance value can be provided by using the 
.B \-i 
or
.B \-I 
option.  The use of the 
.B \-I 
option enables the filling up of images, which are horizontally cut.
If the
option
.B \-d 
is used, all found glare sources and their position, size, and
luminance values are printed to the standard output, too.  The last
line gives following values: (1) DGP, (2) average luminance of image,
(3) vertical eye illuminance, (4) background luminance, (5) direct
vertical eye illuminance, (6) DGI, (7) UGR, (8) VCP, (9) CGI, (10)
average luminance of all glare sources, (11) sum of solid angles of
all glare sources, (12) Veiling luminance (disability glare), (13)
x-direction of glare source, (14) y-direction of glare source, (15)
z-direction of glare source, and (16) band luminance.
.SH OPTIONS
.TP
.BI \-B \ angle
Calculate average luminance of a horizontal band. The angle is in
radians. This calculation does not affect glare source detection.
Output only when using the
.B \-d 
option.
.TP
.BI \-b \ factor
Threshold factor; if factor is over 100, it is used as constant threshold in
cd/m2, regardless if a task position is given or not if
factor is less than or equal to 100 and a task position is given, this
factor multiplied by the average task luminance will be used as
threshold for detecting the glare sources if factor is less than or
equal to 100 and no task position is given, this factor multiplied by
the average luminance in the entire picture will be used as threshold
for detecting the glare sources, default\ 5.
.TP
.BI \-c \ fname
writes a checkfile in the RADIANCE picture format
.TP
.B \-d
enables detailed output (default: disabled)
.TP
.BI \-g \ type
cut field of view according to Guth, write checkfile specified by 
.B \-c
and exit without any glare evaluation.  Type 1: total field of view.
Type 2: field of view seen by both eyes
.TP
.BI \-G \ type
Cut the field of view according to Guth, perform glare evaluation.
Type 1: total field of view. Type 2: field of view seen by both eyes
.TP
.BI \-i \ Ev
The vertical illuminance is measured externally.  This value will be
used for calculating the dgp.
.TP
.BI \-I \ Ev \  y_max \  y_min
The vertical illuminance is measured externally.
This value will be used for calculating the DGP.
Below 
.I y_min 
and above 
.IR y_max , 
the picture is filled up by the last known value.  This option should
be used, when the provided picture is cut horizontally.
.TP
.BI \-r \ angle
search radius (angle in radians) between pixels, where 
.B evalglare
tries
to merge glare source pixels to the same glare source (default value:
0.2 radians)
.TP
.B \-s
enables smoothing function (default: disabled)
.TP
.BI \-t \ xpos \  ypos \  angle
definition of task position in x and y coordinates, and its opening
angle in radians
.TP
.BI \-T \ xpos \  ypos \  angle
same as 
.BR \-t , 
except that the task area is colored bluish in the checkfile
.TP
.BI \-u \ r \  g \  b
color glare sources uniformly when writing check file (implies
.B \-c
option). Color given in r g b.
.TP
.B \-v
show version of 
.B evalglare
and exit
.TP
.B \-V
Just calculate the vertical illuminance and exit
.TP
.B \-x
disable peak extraction
.TP
.B \-y
enables peak extraction (default: enabled)
.TP
.BI \-Y \ value
enables peak extraction with 
.I value 
as threshold for extracted peaks.
.PP
.I "If the view settings in the image file"
are missing or are not valid (e.g.  after the use of
.BR pcompos "(1) or " pcomb (1)), 
the view options can be set by command line options.  If view options
are set on the command line, view options in the image file header are
ignored.  The view options are implemented according to the RADIANCE
definition; please read the
.BR rpict (1)
man page for details.
.sp
.TP
.BI \-vt t
Set view type to t (for fisheye views, please use 
.BI \-vt \ a 
or 
.BI \-vt \ h
preferably)
.TP
.BI \-vf \ viewfile
Get view parameters from file
.TP
.BI \-vv \ val
Set the view vertical size to val
.TP
.BI \-vh \ val
Set the view horizontal size to 
.I val
.SH AUTHOR
Jan Wienold.
.SH SEE ALSO
.BR rpict (1)
.SH REFERENCES
.B Evalglare
is based on the studies by J.  Christoffersen and J.
Wienold (see \*(lqEvaluation methods and development of a new glare
prediction model for daylight environments with the use of CCD cameras
and RADIANCE,\*(rq
.IR "Energy and Buildings 38" ,
2006, pp. 743\-757, doi:10.1016/j.enbuild.2006.03.017.  More
details can be also found in following dissertation: J.  Wienold,
.IR "Daylight glare in offices" ,
Fraunhofer IRB, 2010, available online at
.nh
<http://publica.fraunhofer.de/dokumente/N-141457.html>.
.hy
.SH ACKNOWLEDGEMENTS
The evalglare program was originally developed by Jan Wienold at the
Fraunhofer Institute for Solar Energy Systems in Freiburg, Germany. It
is being further developed and maintained by the same author at EPFL,
Lausanne, Switzerland.
.PP
The author would like to thank C.  Reetz for his generous help and his
support of providing libraries for the program.  The EU Commission
supported this work as part of the EU project \*(lqEnergy and Comfort
Control for Building management systems\*(rq (ECCO-Build, Contract
ENK6-CT-2002-00656).
.PP
German Research Foundation (DFG) contract WI 1304/7-2 supported the research
for the extension of evalglare for low light scenes.
Revision:	1.2
Committed:	Sun Apr 10 04:08:19 2016 UTC (9 years, 2 months ago) by greg
Branch:	MAIN
Changes since 1.1:	+280 -210 lines
Log Message:	Edits and corrections contributed by Randolph Fritz
#	Content
1	.\" RCSid $Id: evalglare.1,v 1.1 2015/08/12 23:07:59 greg Exp $
2	.TH EVALGLARE 1 7/30/15 RADIANCE
3	.SH NAME
4	evalglare \- determines and evaluates glare sources within a 180 degree fisheye HDR image
5	.SH SYNOPSIS
6	.PP
7	.nh
8	.B evalglare
9	[
10	.BI \-s
11	]
12	[
13	.BI \-y
14	]
15	[
16	.BI \-Y \ value
17	]
18	[
19	.BI \-B " angle"
20	]
21	[
22	.BI \-b " factor"
23	]
24	[
25	.BI \-c " checkfile"
26	]
27	[
28	.BI \-t " xpos ypos angle"
29	]
30	[
31	.BI \-T " xpos ypos angle"
32	]
33	[ \-d ]
34	[
35	.BI \-r " angle"
36	]
37	[
38	.BI \-i " Ev"
39	]
40	[
41	.BI \-I " Ev yfill_max y_fill_min"
42	]
43	[
44	.BI \-v
45	]
46	[
47	.BI \-V
48	]
49	[
50	.BI \-g " type"
51	]
52	[
53	.BI \-G " type"
54	]
55	[
56	.BI \-u " r g b"
57	]
58	[
59	.BI \-vf " viewfile"
60	]
61	[
62	.BI \-vt t
63	]
64	[
65	.BI \-vv " vertangle"
66	]
67	[
68	.BI \-vh " horzangle"
69	]
70	.RI [ hdrfile ]
71	.hy
72	.SH DESCRIPTION
73	.PP
74	.B Evalglare
75	determines and evaluates glare sources within a 180 degree fisheye
76	image, given in the RADIANCE image format (.pic or .hdr). If
77	.I hdrfile
78	is not given as an argument, the standard input is read. The image
79	should be rendered as fisheye (e.g. using the
80	.BI \-vt a
81	or
82	.BI \-vt h
83	option) using 180 degrees for the horizontal and vertical view angle
84	.RB ( -vv
85	.IR 180 ,
86	.B -vh
87	.IR 180 ).
88	The recommended size of images input to
89	.B evalglare
90	is 1000x1000 pixels; the computations become very long when the image
91	is more than 1200x1200 pixels.
92	.PP
93	The calculation of glare proceeds in two steps:
94	.IP 1. 3em
95	In the first step, the program uses a given threshold
96	to determine all glare sources. Three different threshold methods are
97	implemented. The recommended method is to define a task area by
98	.B \-t
99	or
100	.B \-T
101	option. The average luminance of the task area is calculated. Each
102	pixel exceeding this value multiplied by the
103	.B \-b
104	factor, default 5, is treated as a potential glare source. The other
105	two methods are described below, see
106	.BR \-b .
107	.IP 2.
108	In the second step, the program tries to merge glare source pixels to
109	one glare source, when they are placed nearby each other. This
110	merging is performed between search areas, given by an opening angle
111	.BR \-r ,
112	default 0.2 radians. If a check file is written,
113	.B \-c
114	.IR fname ,
115	the detected glare sources will be colored, each with a different
116	color, and the rest of the image will be set to gray. The luminance values
117	of all pixels are kept to the initial value. The color is chosen by
118	chance, no significance is given by the color. To enable unform
119	coloring of all glare sources, the
120	.B \-u
121	option can be used. Luminance
122	peaks can be extracted to separate glare sources by using the
123	.B \-y
124	or
125	.BI \-Y " value"
126	option. The default value
127	.B \-y
128	is 50,000 cd/m2, which can be changed by using the
129	.B \-Y
130	value. A smoothing option,
131	.BR \-s ,
132	counts initial non-glare source pixels to glare sources, when they are
133	surrounded by a glare source.
134	.PP
135	The program calculates the daylight glare probability (DGP) as well as
136	other glare indices (DGI, UGR, VCP, CGI) and writes them to the
137	standard output. The DGP describes the fraction of persons disturbed
138	caused by glare from daylight as a number from 0 to 1, where 0 is
139	no-one disturbed and 1 is everyone. Values lower than 0.2 are out of
140	the range of the user assessment tests which the program is based on
141	and should be interpreted carefully. A low light correction is
142	applied to the DGP when the vertical illumiance is lower than 500 lux.
143	By the use of
144	.B \-g
145	or
146	.B \-G
147	.\" Citation?
148	the field of view is cut according the the definition of Guth.
149	The option
150	.B \-B
151	angle (in radians) calculates the average luminance of a
152	horizontal band. In the case of non-180 degree images, an external
153	measured illuminance value can be provided by using the
154	.B \-i
155	or
156	.B \-I
157	option. The use of the
158	.B \-I
159	option enables the filling up of images, which are horizontally cut.
160	If the
161	option
162	.B \-d
163	is used, all found glare sources and their position, size, and
164	luminance values are printed to the standard output, too. The last
165	line gives following values: (1) DGP, (2) average luminance of image,
166	(3) vertical eye illuminance, (4) background luminance, (5) direct
167	vertical eye illuminance, (6) DGI, (7) UGR, (8) VCP, (9) CGI, (10)
168	average luminance of all glare sources, (11) sum of solid angles of
169	all glare sources, (12) Veiling luminance (disability glare), (13)
170	x-direction of glare source, (14) y-direction of glare source, (15)
171	z-direction of glare source, and (16) band luminance.
172	.SH OPTIONS
173	.TP
174	.BI \-B \ angle
175	Calculate average luminance of a horizontal band. The angle is in
176	radians. This calculation does not affect glare source detection.
177	Output only when using the
178	.B \-d
179	option.
180	.TP
181	.BI \-b \ factor
182	Threshold factor; if factor is over 100, it is used as constant threshold in
183	cd/m2, regardless if a task position is given or not if
184	factor is less than or equal to 100 and a task position is given, this
185	factor multiplied by the average task luminance will be used as
186	threshold for detecting the glare sources if factor is less than or
187	equal to 100 and no task position is given, this factor multiplied by
188	the average luminance in the entire picture will be used as threshold
189	for detecting the glare sources, default\ 5.
190	.TP
191	.BI \-c \ fname
192	writes a checkfile in the RADIANCE picture format
193	.TP
194	.B \-d
195	enables detailed output (default: disabled)
196	.TP
197	.BI \-g \ type
198	cut field of view according to Guth, write checkfile specified by
199	.B \-c
200	and exit without any glare evaluation. Type 1: total field of view.
201	Type 2: field of view seen by both eyes
202	.TP
203	.BI \-G \ type
204	Cut the field of view according to Guth, perform glare evaluation.
205	Type 1: total field of view. Type 2: field of view seen by both eyes
206	.TP
207	.BI \-i \ Ev
208	The vertical illuminance is measured externally. This value will be
209	used for calculating the dgp.
210	.TP
211	.BI \-I \ Ev \ y_max \ y_min
212	The vertical illuminance is measured externally.
213	This value will be used for calculating the DGP.
214	Below
215	.I y_min
216	and above
217	.IR y_max ,
218	the picture is filled up by the last known value. This option should
219	be used, when the provided picture is cut horizontally.
220	.TP
221	.BI \-r \ angle
222	search radius (angle in radians) between pixels, where
223	.B evalglare
224	tries
225	to merge glare source pixels to the same glare source (default value:
226	0.2 radians)
227	.TP
228	.B \-s
229	enables smoothing function (default: disabled)
230	.TP
231	.BI \-t \ xpos \ ypos \ angle
232	definition of task position in x and y coordinates, and its opening
233	angle in radians
234	.TP
235	.BI \-T \ xpos \ ypos \ angle
236	same as
237	.BR \-t ,
238	except that the task area is colored bluish in the checkfile
239	.TP
240	.BI \-u \ r \ g \ b
241	color glare sources uniformly when writing check file (implies
242	.B \-c
243	option). Color given in r g b.
244	.TP
245	.B \-v
246	show version of
247	.B evalglare
248	and exit
249	.TP
250	.B \-V
251	Just calculate the vertical illuminance and exit
252	.TP
253	.B \-x
254	disable peak extraction
255	.TP
256	.B \-y
257	enables peak extraction (default: enabled)
258	.TP
259	.BI \-Y \ value
260	enables peak extraction with
261	.I value
262	as threshold for extracted peaks.
263	.PP
264	.I "If the view settings in the image file"
265	are missing or are not valid (e.g. after the use of
266	.BR pcompos "(1) or " pcomb (1)),
267	the view options can be set by command line options. If view options
268	are set on the command line, view options in the image file header are
269	ignored. The view options are implemented according to the RADIANCE
270	definition; please read the
271	.BR rpict (1)
272	man page for details.
273	.sp
274	.TP
275	.BI \-vt t
276	Set view type to t (for fisheye views, please use
277	.BI \-vt \ a
278	or
279	.BI \-vt \ h
280	preferably)
281	.TP
282	.BI \-vf \ viewfile
283	Get view parameters from file
284	.TP
285	.BI \-vv \ val
286	Set the view vertical size to val
287	.TP
288	.BI \-vh \ val
289	Set the view horizontal size to
290	.I val
291	.SH AUTHOR
292	Jan Wienold.
293	.SH SEE ALSO
294	.BR rpict (1)
295	.SH REFERENCES
296	.B Evalglare
297	is based on the studies by J. Christoffersen and J.
298	Wienold (see \*(lqEvaluation methods and development of a new glare
299	prediction model for daylight environments with the use of CCD cameras
300	and RADIANCE,\*(rq
301	.IR "Energy and Buildings 38" ,
302	2006, pp. 743\-757, doi:10.1016/j.enbuild.2006.03.017. More
303	details can be also found in following dissertation: J. Wienold,
304	.IR "Daylight glare in offices" ,
305	Fraunhofer IRB, 2010, available online at
306	.nh
307	<http://publica.fraunhofer.de/dokumente/N-141457.html>.
308	.hy
309	.SH ACKNOWLEDGEMENTS
310	The evalglare program was originally developed by Jan Wienold at the
311	Fraunhofer Institute for Solar Energy Systems in Freiburg, Germany. It
312	is being further developed and maintained by the same author at EPFL,
313	Lausanne, Switzerland.
314	.PP
315	The author would like to thank C. Reetz for his generous help and his
316	support of providing libraries for the program. The EU Commission
317	supported this work as part of the EU project \*(lqEnergy and Comfort
318	Control for Building management systems\*(rq (ECCO-Build, Contract
319	ENK6-CT-2002-00656).
320	.PP
321	German Research Foundation (DFG) contract WI 1304/7-2 supported the research
322	for the extension of evalglare for low light scenes.