man/man1/mkillum.1

.\" RCSid "$Id: mkillum.1,v 1.7 2007/12/13 07:03:36 greg Exp $"
.TH MKILLUM 1 10/6/95 RADIANCE
.SH NAME
mkillum - compute illum sources for a RADIANCE scene
.SH SYNOPSIS
.B mkillum
[
.B "\-n nprocs"
][
.B "rtrace options"
]
.B octree
.B "[ \< file .. ]"
.br
.B "mkillum [ rtrace options ] \-defaults"
.SH DESCRIPTION
.I Mkillum
takes a prepared RADIANCE scene description and an octree and computes
light source distributions for each surface, replacing them with
secondary sources whose contributions can be computed more efficiently by
.I rpict(1)
and
.I rvu(1).
This type of optimization is most useful for windows and skylights which
represent concentrated sources of indirect illumination.
.I Mkillum
is not appropriate for very large sources or sources with highly
directional distributions.
These are best handled respectively by the ambient calculation
and the secondary source types in RADIANCE.
.PP
If the
.I \-n
option is specified with a value greater than 1, multiple
.I rtrace(1)
processes will be used to accelerate computation on a shared
memory machine.
Note that there is no benefit to using more processes
than there are local CPUs available to do the work.
.PP
Remaining arguments to
.I mkillum
are passed directly to
.I rtrace(1),
which is used to compute the light distributions for the input surfaces.
These surfaces can be any combination of polygons, spheres and rings.
Other surfaces may be included, but
.I mkillum
cannot compute their distributions.
.PP
By default,
.I mkillum
reads from its standard input and writes to its standard output.
It is possible to specify multiple input files in a somewhat
unconventional fashion by placing a lesser-than symbol ('<') before
the file names.
(Note that this character must be escaped from most shells.)
This is necessary so
.I mkillum
can tell where the arguments to
.I rtrace(1)
end and its own input files begin.
.SH VARIABLES
.I Mkillum
has a number of parameters that can be changed by
comments in the input file of the form:
.nf

        #@mkillum variable=value option switch{+|-} ..

.fi
String or integer variables are separated from their values by the
equals sign ('=').
Options appear by themselves.
Switches are followed either by a
plus sign to turn them on or a minus sign to turn them off.
.PP
Parameters are usually changed many times within the
same input file to tailor the calculation, specify different
labels and so on.
The parameters and their meanings are described below.
.TP 10n
.BI o =string
Set the output file to
.I string.
All subsequent scene data will be sent to this file.
If this appears in the first comment in the input, nothing will be
sent to the standard output.
Note that this is not recommended when running
.I mkillum
from
.I rad(1),
which expects the output to be on the standard output.
.TP
.BI m =string
Set the material identifier to
.I string.
This name will be used not only as the new surface modifier, but it
will also be used to name the distribution pattern and the data files.
The distribution name will be
.I string
plus the suffix ".dist".
The data file will be named
.I string
plus possibly an integer plus a ".dat" suffix.
The integer is used to avoid accidently writing over an existing
file.
If overwriting the file is desired, use the
.I f
variable below.
.TP
.BI f =string
Set the data file name to
.I string.
The next data file will be given this name plus a ".dat" suffix.
Subsequent files will be named
.I string
plus an integer plus the ".dat" suffix.
An existing file with the same name will be clobbered.
This variable may be unset by leaving off the value.
(See also the
.I m
variable above.)
.TP
.BR a
Produce secondary sources for all of the surfaces in the input.
This is the default.
.TP
.BI e =string
Produce secondary sources for all surfaces except those modified by
.I string.
Surfaces modified by
.I string
will be passed to the output unchanged.
.TP
.BI i =string
Only produce secondary sources for surfaces modified by
.I string.
.TP
.BR n
Do not produce any secondary sources.
All input will be passed to the output unaffected, except any
void surfaces will be removed.
.TP
.BI b =real
Do not produce a secondary source for a surface if its average
brightness (radiance) is less than the value
.I real.
.TP
.BI c ={d|a|n}
Use color information according to the given character.
If the character is
.I d,
then color information will be used in three separate data files and
the distribution will be fully characterized in terms of color.
If the character is
.I a,
then only the average color is computed and the distribution will
not contain color information.
If the character is
.I n,
even the average distribution color will be thrown away,
producing secondary sources that are completely uncolored.
This may be desirable from a color-balancing point of view.
.TP
.BI d =integer
Set the number of direction samples per projected steradian to
.I integer.
The number of directions stored in the associated data file will be
approximately this number multiplied by pi for polygons and rings, and
by 4pi for spheres.
If
.I integer
is zero, then a diffuse source is assumed and no distribution is
created.
.TP
.BI d =string
Set the surface Bidirectional Scattering Distribution Function (BSDF)
to the given file.
The RADIANCE library path will be searched if the file does not begin
with a '.' or '~' character.
This file must contain an LBNL Window 6 XML specification of a valid
BSDF for the given surface, and all rays will be interpreted through
this function.
The orientation of the BSDF may be controlled with the
.I u
setting, described below.
The thickness of the surface may be controlled with the
.I t
setting.
If this variable has no setting or an integer is specified,
.I mkillum
returns to the default behavior of computing the output distribution
directly.
.TP
.BI s =integer
Set the number of ray samples per direction to
.I integer.
This variable affects the accuracy of the distribution value for
each direction as well as the computation time for
.I mkillum.
.TP
.BR l{+|-}
Switch between light sources and illum sources.
If this switch is enabled
.I (l+),
.I mkillum
will use the material type "light" to represent surfaces.
If disabled
.I (l-),
.I mkillum
will use the material type "illum" with the input surface modifier
as its alternate material.
The default is
.I l-.
.TP
.BI u =[+|-]{X|Y|Z}
The given axis will be considered "up" for the purposes of interpreting
BSDF data specified with the
.I d
variable.
The BSDF will be reoriented relative to the surface as necessary to keep
the up vector in the vertical plane that contains this axis and the
surface normal, corresponding to an azimuth of 90 degrees.
The default up vector is +Z.
.TP
.BI t =real
Set the surface thickness to
.I real
in world coordinates.
This value is used for determining where to start rays that need to begin
on the opposite side of the surface, specifically to compute the incoming
distribution for a BSDF computation.
The default value is 0.
.SH EXAMPLES
The following command generates illum's corresponding to geometry
in the files "it1.rad" and "it2.rad":
.IP "" .3i
mkillum \-ab 2 \-ad 1024 \-av .1 .1 .1 basic.oct "<" it1.rad it2.rad > illums.rad
.PP
The output file "illums.rad" would then be combined with the original
scene geometry to create a more easily rendered composite.
.SH ENVIRONMENT
RAYPATH         the directories to check for auxiliary files.
.SH AUTHOR
Greg Ward
.SH ACKNOWLEDGEMENT
Work on this program was initiated and sponsored by the LESO
group at EPFL in Switzerland.
.SH "SEE ALSO"
oconv(1), rad(1), rpict(1), rtrace(1), rvu(1)
Revision:	1.8
Committed:	Fri Apr 18 00:39:24 2008 UTC (16 years ago) by greg
Branch:	MAIN
CVS Tags:	rad3R9
Changes since 1.7:	+3 -3 lines
Log Message:	Added clarification of "up" orientation for BSDFs
#	Content
1	.\" RCSid "$Id: mkillum.1,v 1.7 2007/12/13 07:03:36 greg Exp $"
2	.TH MKILLUM 1 10/6/95 RADIANCE
3	.SH NAME
4	mkillum - compute illum sources for a RADIANCE scene
5	.SH SYNOPSIS
6	.B mkillum
7	[
8	.B "\-n nprocs"
9	][
10	.B "rtrace options"
11	]
12	.B octree
13	.B "[ \< file .. ]"
14	.br
15	.B "mkillum [ rtrace options ] \-defaults"
16	.SH DESCRIPTION
17	.I Mkillum
18	takes a prepared RADIANCE scene description and an octree and computes
19	light source distributions for each surface, replacing them with
20	secondary sources whose contributions can be computed more efficiently by
21	.I rpict(1)
22	and
23	.I rvu(1).
24	This type of optimization is most useful for windows and skylights which
25	represent concentrated sources of indirect illumination.
26	.I Mkillum
27	is not appropriate for very large sources or sources with highly
28	directional distributions.
29	These are best handled respectively by the ambient calculation
30	and the secondary source types in RADIANCE.
31	.PP
32	If the
33	.I \-n
34	option is specified with a value greater than 1, multiple
35	.I rtrace(1)
36	processes will be used to accelerate computation on a shared
37	memory machine.
38	Note that there is no benefit to using more processes
39	than there are local CPUs available to do the work.
40	.PP
41	Remaining arguments to
42	.I mkillum
43	are passed directly to
44	.I rtrace(1),
45	which is used to compute the light distributions for the input surfaces.
46	These surfaces can be any combination of polygons, spheres and rings.
47	Other surfaces may be included, but
48	.I mkillum
49	cannot compute their distributions.
50	.PP
51	By default,
52	.I mkillum
53	reads from its standard input and writes to its standard output.
54	It is possible to specify multiple input files in a somewhat
55	unconventional fashion by placing a lesser-than symbol ('<') before
56	the file names.
57	(Note that this character must be escaped from most shells.)
58	This is necessary so
59	.I mkillum
60	can tell where the arguments to
61	.I rtrace(1)
62	end and its own input files begin.
63	.SH VARIABLES
64	.I Mkillum
65	has a number of parameters that can be changed by
66	comments in the input file of the form:
67	.nf
68
69	#@mkillum variable=value option switch{+\|-} ..
70
71	.fi
72	String or integer variables are separated from their values by the
73	equals sign ('=').
74	Options appear by themselves.
75	Switches are followed either by a
76	plus sign to turn them on or a minus sign to turn them off.
77	.PP
78	Parameters are usually changed many times within the
79	same input file to tailor the calculation, specify different
80	labels and so on.
81	The parameters and their meanings are described below.
82	.TP 10n
83	.BI o =string
84	Set the output file to
85	.I string.
86	All subsequent scene data will be sent to this file.
87	If this appears in the first comment in the input, nothing will be
88	sent to the standard output.
89	Note that this is not recommended when running
90	.I mkillum
91	from
92	.I rad(1),
93	which expects the output to be on the standard output.
94	.TP
95	.BI m =string
96	Set the material identifier to
97	.I string.
98	This name will be used not only as the new surface modifier, but it
99	will also be used to name the distribution pattern and the data files.
100	The distribution name will be
101	.I string
102	plus the suffix ".dist".
103	The data file will be named
104	.I string
105	plus possibly an integer plus a ".dat" suffix.
106	The integer is used to avoid accidently writing over an existing
107	file.
108	If overwriting the file is desired, use the
109	.I f
110	variable below.
111	.TP
112	.BI f =string
113	Set the data file name to
114	.I string.
115	The next data file will be given this name plus a ".dat" suffix.
116	Subsequent files will be named
117	.I string
118	plus an integer plus the ".dat" suffix.
119	An existing file with the same name will be clobbered.
120	This variable may be unset by leaving off the value.
121	(See also the
122	.I m
123	variable above.)
124	.TP
125	.BR a
126	Produce secondary sources for all of the surfaces in the input.
127	This is the default.
128	.TP
129	.BI e =string
130	Produce secondary sources for all surfaces except those modified by
131	.I string.
132	Surfaces modified by
133	.I string
134	will be passed to the output unchanged.
135	.TP
136	.BI i =string
137	Only produce secondary sources for surfaces modified by
138	.I string.
139	.TP
140	.BR n
141	Do not produce any secondary sources.
142	All input will be passed to the output unaffected, except any
143	void surfaces will be removed.
144	.TP
145	.BI b =real
146	Do not produce a secondary source for a surface if its average
147	brightness (radiance) is less than the value
148	.I real.
149	.TP
150	.BI c ={d\|a\|n}
151	Use color information according to the given character.
152	If the character is
153	.I d,
154	then color information will be used in three separate data files and
155	the distribution will be fully characterized in terms of color.
156	If the character is
157	.I a,
158	then only the average color is computed and the distribution will
159	not contain color information.
160	If the character is
161	.I n,
162	even the average distribution color will be thrown away,
163	producing secondary sources that are completely uncolored.
164	This may be desirable from a color-balancing point of view.
165	.TP
166	.BI d =integer
167	Set the number of direction samples per projected steradian to
168	.I integer.
169	The number of directions stored in the associated data file will be
170	approximately this number multiplied by pi for polygons and rings, and
171	by 4pi for spheres.
172	If
173	.I integer
174	is zero, then a diffuse source is assumed and no distribution is
175	created.
176	.TP
177	.BI d =string
178	Set the surface Bidirectional Scattering Distribution Function (BSDF)
179	to the given file.
180	The RADIANCE library path will be searched if the file does not begin
181	with a '.' or '~' character.
182	This file must contain an LBNL Window 6 XML specification of a valid
183	BSDF for the given surface, and all rays will be interpreted through
184	this function.
185	The orientation of the BSDF may be controlled with the
186	.I u
187	setting, described below.
188	The thickness of the surface may be controlled with the
189	.I t
190	setting.
191	If this variable has no setting or an integer is specified,
192	.I mkillum
193	returns to the default behavior of computing the output distribution
194	directly.
195	.TP
196	.BI s =integer
197	Set the number of ray samples per direction to
198	.I integer.
199	This variable affects the accuracy of the distribution value for
200	each direction as well as the computation time for
201	.I mkillum.
202	.TP
203	.BR l{+\|-}
204	Switch between light sources and illum sources.
205	If this switch is enabled
206	.I (l+),
207	.I mkillum
208	will use the material type "light" to represent surfaces.
209	If disabled
210	.I (l-),
211	.I mkillum
212	will use the material type "illum" with the input surface modifier
213	as its alternate material.
214	The default is
215	.I l-.
216	.TP
217	.BI u =[+\|-]{X\|Y\|Z}
218	The given axis will be considered "up" for the purposes of interpreting
219	BSDF data specified with the
220	.I d
221	variable.
222	The BSDF will be reoriented relative to the surface as necessary to keep
223	the up vector in the vertical plane that contains this axis and the
224	surface normal, corresponding to an azimuth of 90 degrees.
225	The default up vector is +Z.
226	.TP
227	.BI t =real
228	Set the surface thickness to
229	.I real
230	in world coordinates.
231	This value is used for determining where to start rays that need to begin
232	on the opposite side of the surface, specifically to compute the incoming
233	distribution for a BSDF computation.
234	The default value is 0.
235	.SH EXAMPLES
236	The following command generates illum's corresponding to geometry
237	in the files "it1.rad" and "it2.rad":
238	.IP "" .3i
239	mkillum \-ab 2 \-ad 1024 \-av .1 .1 .1 basic.oct "<" it1.rad it2.rad > illums.rad
240	.PP
241	The output file "illums.rad" would then be combined with the original
242	scene geometry to create a more easily rendered composite.
243	.SH ENVIRONMENT
244	RAYPATH the directories to check for auxiliary files.
245	.SH AUTHOR
246	Greg Ward
247	.SH ACKNOWLEDGEMENT
248	Work on this program was initiated and sponsored by the LESO
249	group at EPFL in Switzerland.
250	.SH "SEE ALSO"
251	oconv(1), rad(1), rpict(1), rtrace(1), rvu(1)