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.\" RCSid "$Id: mkillum.1,v 1.3 2004/01/01 19:31:45 greg Exp $" |
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.TH MKILLUM 1 10/6/95 RADIANCE |
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.SH NAME |
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mkillum - compute illum sources for a RADIANCE scene |
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.SH SYNOPSIS |
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.B mkillum |
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[ |
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.B "\-n nprocs" |
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][ |
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.B "rtrace options" |
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] |
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.B octree |
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.B "[ \< file .. ]" |
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.br |
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.B "mkillum [ rtrace options ] \-defaults" |
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.SH DESCRIPTION |
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.I Mkillum |
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takes a prepared RADIANCE scene description and an octree and computes |
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light source distributions for each surface, replacing them with |
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secondary sources whose contributions can be computed more efficiently by |
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.I rpict(1) |
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and |
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.I rvu(1). |
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This type of optimization is most useful for windows and skylights which |
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represent concentrated sources of indirect illumination. |
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.I Mkillum |
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is not appropriate for very large sources or sources with highly |
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directional distributions. |
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These are best handled respectively by the ambient calculation |
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and the secondary source types in RADIANCE. |
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.PP |
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If the |
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.I \-n |
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option is specified with a value greater than 1, multiple |
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.I rtrace(1) |
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processes will be used to accelerate computation on a shared |
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memory machine. |
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Note that there is no benefit to using more processes |
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than there are local CPUs available to do the work. |
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.PP |
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Remaining arguments to |
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.I mkillum |
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are passed directly to |
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.I rtrace(1), |
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which is used to compute the light distributions for the input surfaces. |
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These surfaces can be any combination of polygons, spheres and rings. |
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Other surfaces may be included, but |
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.I mkillum |
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cannot compute their distributions. |
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.PP |
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By default, |
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.I mkillum |
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reads from its standard input and writes to its standard output. |
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It is possible to specify multiple input files in a somewhat |
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unconventional fashion by placing a lesser-than symbol ('<') before |
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the file names. |
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(Note that this character must be escaped from most shells.) |
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This is necessary so |
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.I mkillum |
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can tell where the arguments to |
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.I rtrace(1) |
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end and its own input files begin. |
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.SH VARIABLES |
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.I Mkillum |
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has a number of parameters that can be changed by |
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comments in the input file of the form: |
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.nf |
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|
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#@mkillum variable=value option switch{+|-} .. |
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|
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.fi |
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String or integer variables are separated from their values by the |
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equals sign ('='). |
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Options appear by themselves. |
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Switches are followed either by a |
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plus sign to turn them on or a minus sign to turn them off. |
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.PP |
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Parameters are usually changed many times within the |
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same input file to tailor the calculation, specify different |
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labels and so on. |
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The parameters and their meanings are described below. |
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.TP 10n |
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.BI o =string |
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Set the output file to |
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.I string. |
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All subsequent scene data will be sent to this file. |
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If this appears in the first comment in the input, nothing will be |
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sent to the standard output. |
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Note that this is not recommended when running |
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.I mkillum |
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from |
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.I rad(1), |
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which expects the output to be on the standard output. |
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.TP |
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.BI m =string |
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Set the material identifier to |
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.I string. |
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This name will be used not only as the new surface modifier, but it |
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will also be used to name the distribution pattern and the data files. |
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The distribution name will be |
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.I string |
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plus the suffix ".dist". |
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The data file will be named |
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.I string |
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plus possibly an integer plus a ".dat" suffix. |
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The integer is used to avoid accidently writing over an existing |
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file. |
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If overwriting the file is desired, use the |
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.I f |
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variable below. |
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.TP |
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.BI f =string |
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Set the data file name to |
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.I string. |
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The next data file will be given this name plus a ".dat" suffix. |
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Subsequent files will be named |
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.I string |
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plus an integer plus the ".dat" suffix. |
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An existing file with the same name will be clobbered. |
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This variable may be unset by leaving off the value. |
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(See also the |
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.I m |
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variable above.) |
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.TP |
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.BR a |
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Produce secondary sources for all of the surfaces in the input. |
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This is the default. |
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.TP |
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.BI e =string |
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Produce secondary sources for all surfaces except those modified by |
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.I string. |
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Surfaces modified by |
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.I string |
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will be passed to the output unchanged. |
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.TP |
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.BI i =string |
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Only produce secondary sources for surfaces modified by |
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.I string. |
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.TP |
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.BR n |
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Do not produce any secondary sources. |
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All input will be passed to the output unaffected. |
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.TP |
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.BI b =real |
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Do not produce a secondary source for a surface if its average |
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brightness (radiance) is less than the value |
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.I real. |
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.TP |
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.BI c ={d|a|n} |
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Use color information according to the given character. |
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If the character is |
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.I d, |
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then color information will be used in three separate data files and |
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the distribution will be fully characterized in terms of color. |
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If the character is |
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.I a, |
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then only the average color is computed and the distribution will |
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not contain color information. |
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If the character is |
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.I n, |
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even the average distribution color will be thrown away, |
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producing secondary sources that are completely uncolored. |
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This may be desirable from a color-balancing point of view. |
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.TP |
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.BI d =integer |
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Set the number of direction samples per projected steradian to |
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.I integer. |
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The number of directions stored in the associated data file will be |
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approximately this number multiplied by pi for polygons and rings, and |
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by 4pi for spheres. |
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If |
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.I integer |
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is zero, then a diffuse source is assumed and no distribution is |
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created. |
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.TP |
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.BI s =integer |
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Set the number of ray samples per direction to |
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.I integer. |
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This variable affects the accuracy of the distribution value for |
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each direction as well as the computation time for |
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.I mkillum. |
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.TP |
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.BR l{+|-} |
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Switch between light sources and illum sources. |
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If this switch is enabled |
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.I (l+), |
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.I mkillum |
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will use the material type "light" to represent surfaces. |
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If disabled |
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.I (l-), |
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.I mkillum |
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will use the material type "illum" with the input surface modifier |
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as its alternate material. |
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The default is |
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.I l-. |
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.SH AUTHOR |
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Greg Ward |
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.SH ACKNOWLEDGEMENT |
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Work on this program was initiated and sponsored by the LESO |
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group at EPFL in Switzerland. |
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.SH "SEE ALSO" |
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oconv(1), rad(1), rpict(1), rtrace(1), rvu(1) |