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Revision 1.26 by greg, Wed Nov 29 18:56:28 2023 UTC

# Line 1 | Line 1
1   .\" RCSid "$Id$"
2 < .TH RMTXOP 1 7/8/97 RADIANCE
2 > .TH RMTXOP 1 5/31/2014 RADIANCE
3   .SH NAME
4   rmtxop - concatenate, add, multiply, divide, transpose, scale, and convert matrices
5   .SH SYNOPSIS
# Line 11 | Line 11 | rmtxop - concatenate, add, multiply, divide, transpose
11   ][
12   .B \-t
13   ][
14 + .B "\-c ce .."
15 + ][
16   .B "\-s sf .."
17   ][
18 < .B "\-c ce .."
18 > .B "\-rf|\-rb"
19   ]
20   .B m1
21   [
22 < .B "+*/"
22 > .B ".+*/"
23   ]
24   .B ".."
25   .SH DESCRIPTION
# Line 30 | Line 32 | Each file must have a header containing the following
32   NROWS={number of rows}
33   NCOLS={number of columns}
34   NCOMP={number of components}
35 < FORMAT={ascii|float|double|32-bit_rle_rgbe|32-bit_rle_xyze}
34 < .sp
35 > FORMAT={ascii|float|double|32-bit_rle_rgbe|32-bit_rle_xyze|Radiance_spectra}
36   .fi
37 + .sp
38   The number of components indicates that each matrix element is actually
39   composed of multiple elements, most commonly an RGB triple.
40   This is essentially dividing the matrix into planes, where each component
# Line 47 | Line 49 | instead of a file by
49   using quotes and a beginning exclamation point ('!').
50   .PP
51   Two special cases are handled for component matrices that are either
52 < XML files containing BTDF data, or Radiance picture files.
53 < In the first case, a BSDF library is used to load and interpret the
54 < transmission matrix.
52 > XML files containing BSDF data, or Radiance picture files.
53 > In the first case, the BSDF library loads and interprets the
54 > transmission matrix by default.
55 > Alternatively, the front (normal-side) reflectance is selected if the
56 > .I \-rf
57 > option precedes the file name, or the backside reflectance if
58 > .I \-rb
59 > is specified.
60   (XML files cannot be read from the standard input or from a command.)\0
61   In the second case, the RGBE or XYZE values are loaded in a 3-component
62   matrix where the number of columns match the X-dimension of the picture, and
63   the number of rows match the Y-dimension.
64   The picture must be in standard pixel ordering, and the first row
65   is at the top with the first column on the left.
66 + Any exposure changes that were applied to the pictures before
67 + .I rmtxop
68 + will be undone, similar to the
69 + .I pcomb(1)
70 + .I \-o
71 + option.
72 + Radiance spectral pictures with more than 3 components are also supported.
73 + These are typically produced by
74 + .I rtrace(1)
75 + or
76 + .I rfluxmtx(1).
77   .PP
78   Before each file, the
79   .I \-t
80   and
63 .I \-s
64 or
81   .I \-c
82 + and/or
83 + .I \-s
84   options may be used to modify the matrix.
85   The
86   .I \-t
87   option transposes the matrix, swapping rows and columns.
88   The
71 .I \-s
72 option applies the given scalar factor(s) to the elements of the matrix.
73 If only one factor is provided,
74 it will be used for all components.
75 If multiple factors are given, their number must match the number of matrix
76 components.
77 Alternatively, the
89   .I \-c
90 < option may be used to "transform" the element values, possibly changing
90 > option can "transform" the element values, possibly changing
91   the number of components in the matrix.
92   For example, a 3-component matrix can be transformed into a single-component
93   matrix by using
# Line 88 | Line 99 | the first new component, and the second four coefficie
99   yield the second new component.
100   Note that the number of coefficients must be an even multiple of the number
101   of original components.
102 < The
102 > Alternatively, a set of symbolic output components can be specified as capital
103 > letters, with the following definitions:
104 > .sp
105 > .nf
106 > R       - red channel
107 > G       - green channel
108 > B       - blue channel
109 > X       - CIE X channel
110 > Y       - CIE Y channel (aka., luminance or illuminance)
111 > Z       - CIE Z channel
112 > S       - scotopic luminance or illuminance
113 > M       - melanopic luminance or illuminance
114 > A       - average component value
115 > .fi
116 > .sp
117 > These letters may be given in any order as a single string, and if
118 > .I "-c RGB"
119 > or
120 > .I "-c XYZ"
121 > is specified along with a
122 > .I "-fc"
123 > option, the output will be written as a RGBE or XYZE picture, respectively.
124 > Note that conversion from a float or RGBE color space applies a conversion
125 > of 179 lumens/watt (for CIE or melanopic output) or 412 (for scotopic output),
126 > and the reverse happens for conversion from XYZE input to RGB or RGBE output.
127 > .PP
128 > Additionally, the
129   .I \-s
130 < and
130 > option applies the given scalar factor(s) to the elements of the matrix.
131 > If only one factor is provided,
132 > it will be used for all components.
133 > If multiple factors are given, their number must match the number of matrix
134 > components
135 > .I after
136 > application of any
137   .I \-c
138 < options are mutually exclusive, insofar as they cannot be applied together
96 < to the same input matrix.
138 > option for this input matrix or picture.
139   .PP
140   If present, the second and subsequent matrices on the command
141 < line are concatenated to the result unless separated by a plus ('+'),
141 > line are concatenated together, unless separated by a plus ('+'),
142   asterisk ('*'), or forward slash ('/') symbol,
143 < in which case the matrix elements are added, multiplied, or divided together,
144 < respectively.
145 < (Note that the asterisk must be quoted or escaped in most shells.)\0
143 > in which case the individual matrix elements are added,
144 > multiplied, or divided, respectively.
145 > The concatenation operator ('.') is the default and need not be specified.
146 > Note also that the asterisk must be quoted or escaped in most shells.
147   In the case of addition, the two matrices involved must have the same number
148   of components.
149 + If subtraction is desired, use addition ('+') with a scaling parameter of -1
150 + for the second matrix (the
151 + .I \-s
152 + option).
153   For element-wise multiplication and division, the second matrix is
154 < permitted instead to have a single component per element, which will be
154 > permitted to have a single component per element, which will be
155   applied equally to all components of the first matrix.
156   If element-wise division is specified, any zero elements in the second
157   matrix will result in a warning and the corresponding component(s) in the
158   first matrix will be set to zero.
159   .PP
160 < The number of components in the new matrix after applying any
160 > Evaluation proceeds from left to right, and all operations have
161 > the same precedence.
162 > If a different evaluation order is desired, pipe the result of one
163 > .I rmtxop
164 > command into another, as shown in one of the examples below.
165 > .PP
166 > The number of components in the next matrix after applying any
167   .I -c
168   transform must agree with the prior result.
169   For concatenation (matrix multiplication), the number of columns
170 < in the prior result must equal the number of rows in the new matrix, and
170 > in the prior result must equal the number of rows in the next matrix, and
171   the result will have the number of rows of the previous and the number
172 < of columns of the new matrix.
172 > of columns of the next matrix.
173   In the case of addition, multiplication, and division,
174   the number of rows and columns of the prior result and the
175 < new matrix must match, and will not be changed by the operation.
175 > next matrix must match, and will not be changed by the operation.
176   .PP
177 + A final transpose or transform/scaling operation may be applied to
178 + the results by appending the
179 + .I \-t
180 + and
181 + .I \-c
182 + and/or
183 + .I \-s
184 + options after the last matrix on the command line.
185 + .PP
186   Results are sent to the standard output.
187   By default, the values will be written in the lowest resolution format
188   among the inputs, but the
189   .I \-f
190   option may be used to explicitly output components
191 < as ASCII (-fa), binary doubles (-fd), floats (-ff), or RGBE colors (-fc).
191 > as ASCII (-fa), binary doubles (-fd), floats (-ff), or common-exponent
192 > colors/spectra (-fc).
193   In the latter case, the actual matrix dimensions are written in the resolution
194   string rather than the header.
195 < Also, matrix results written as Radiance pictures must have either one
195 > Also, matrix results will be written as standard
196 > Radiance pictures if they have either one
197   or three components.
198   In the one-component case, the output is written as grayscale.
199 + If more than 3 components are in the final matrix and
200 + .I -fc
201 + is specified, the output will be a Radiance spectral picture.
202   .PP
203   The
204   .I \-v
# Line 146 | Line 213 | To convert a BTDF matrix into a Radiance picture:
213   .IP "" .2i
214   rmtxop -fc blinds.xml > blinds.hdr
215   .PP
216 + To extract the luminance values from a picture as an ASCII matrix:
217 + .IP "" .2i
218 + rmtxop -fa -c .265 .670 .065 image.hdr > image_lum.mtx
219 + .PP
220 + To render a melanopic illuminance image with
221 + .I rtrace\:
222 + .IP "" .2i
223 + vwrays -ff -x 1024 -y 1024 -vf myview.vf |
224 + rtrace -fff -cs 18 -co+ -i+ `vwrays -x 1024 -y 1024 -vf myview.vf -d` scene.oct |
225 + rmtxop -fc -c M - > scene_meli.hdr
226 + .PP
227   To scale a matrix by 4 and add it to the transpose of another matrix:
228   .IP "" .2i
229 < rmtxop -s 4 left.mtx + -t right.mtx > result.mtx
229 > rmtxop -s 4 first.mtx + -t second.mtx > result.mtx
230   .PP
231 + To multiply elements of two matrices, then concatenate with a third,
232 + applying a final transpose to the result:
233 + .IP "" .2i
234 + rmtxop first.mtx \\* second.mtx . third.mtx -t > result.mtx
235 + .PP
236 + To left-multiply the element-wise division of two matrices:
237 + .IP "" .2i
238 + rmtxop -fd numerator.mtx / denominator.mtx | rmtxop left.mtx - > result.mtx
239 + .PP
240   To send the elements of a binary matrix to
241   .I rcalc(1)
242   for further processing:
243   .IP "" .2i
244   rmtxop -fa orig.mtx | rcollate -ho -oc 1 | rcalc [operations]
245 + .SH NOTES
246 + Matrix concatenation is associative but not commutative, so order
247 + matters to the result.
248 + .I Rmtxop
249 + takes advantage of this associative property to concatenate
250 + from right to left when it reduces the number of basic operations.
251 + If the rightmost matrix is a column vector for example, it is
252 + much faster to concatenate from the right, and the result will
253 + be the same.
254 + Note that this only applies to concatenation;
255 + element-wise addition, multiplication, and division are always
256 + evaluated from left to right.
257   .SH AUTHOR
258   Greg Ward
259   .SH "SEE ALSO"
260 < cnt(1), getinfo(1), histo(1), neaten(1), rcalc(1), rcollate(1),
261 < rcontrib(1), rfluxmtx(1), rlam(1), tabfunc(1), total(1), wrapBSDF(1)
260 > cnt(1), getinfo(1), histo(1), neaten(1), pcomb(1),
261 > ra_xyze(1), rcalc(1),
262 > rcollate(1), rcontrib(1), rcrop(1), rfluxmtx(1), rlam(1),
263 > rsplit(1), rtrace(1), tabfunc(1), total(1), vwrays(1),
264 > wrapBSDF(1)

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