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.\" RCSid "$Id: rsensor.1,v 1.4 2010/09/26 15:41:46 greg Exp $"
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.TH RSENSOR 1 4/11/2008 RADIANCE
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.SH NAME
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rsensor - compute sensor signal from a RADIANCE scene
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.SH SYNOPSIS
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.B rsensor
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[
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.B -n nprocs
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][
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.B -h
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][
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.B render options
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]
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[
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.B $EVAR
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]
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[
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.B @file
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]
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{
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[
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.B -rd nrays
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][
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.B -dn nsrc
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][
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.B sensor_view
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]
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.B sensor_file ..
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}
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.B octree
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.br
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.B rsensor
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[
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.B -h
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]
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{
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[
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.B -rd nrays
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][
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.B sensor_view
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]
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.B sensor_file ..
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}
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.B "."
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.br
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.B "rsensor [ options ] \-defaults"
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.SH DESCRIPTION
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.I Rsensor
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traces rays outward from one or more specified illumination
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sensors into the RADIANCE scene given by
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.I octree,
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sending the computed sensor value to the standard output.
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(The octree may be given as the output of a command enclosed in quotes
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and preceded by a `!'.)\0
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In the second form, a single period ('.') is given in place of an
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octree, and the origin and directions of the specified
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number of rays will be printed on the standard output.
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If these rays are later traced and added together, the results
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will sum to a signal proportional to the given sensor distribution.
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In the third form, the default values
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for the options (modified by those options present)
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are printed with a brief explanation.
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.PP
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Options may be given on the command line and/or read from the
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environment and/or read from a file.
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A command argument beginning with a dollar sign ('$') is immediately
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replaced by the contents of the given environment variable.
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A command argument beginning with an at sign ('@') is immediately
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replaced by the contents of the given file.
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.PP
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The sensor files themselves will be searched for in the path
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locations specified by the
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.I RAYPATH
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environment variable, similar to other types of Radiance
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auxiliary files.
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If the sensor file path begins with '/', '.' or '~', no search
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will take place.
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Before each sensor file, a separate view may be specified.
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In this case, the view origin and direction will correspond to
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the position and orientation of the sensor, and the view up
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vector will determine the zero azimuthal direction of the sensor.
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The fore clipping distance may be used as well, but other view
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options will be ignored.
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(See
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.I rpict(1)
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for details on how to specify a view.)\0
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The actual data contained in the sensor file corresponds to the
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.I SPOT
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tab-separated matrix specification, where the
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column header has "degrees" in the leftmost column, followed
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by evenly-spaced azimuthal angles.
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Each row begins with the polar angle, and is followed by the
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relative sensitivity values for each direction.
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A low-resolution example of a sensor file is given below:
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.sp
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.nf
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degrees 0 90 180 270
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0 .02 .04 .02 .04
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45 .01 .02 .01 .02
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90 .001 .002 .001 .002
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.fi
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.sp
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As well as different views, the number of samples may be changed between
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sensors, where the
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.I \-rd
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option controls the number of ray samples sent at random, and the
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.I \-dn
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option controls the number of rays sent to each light source per sensor.
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.PP
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The
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.I \-h
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option toggles header output, which defaults to "on."
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The
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.I \-n
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option may be used to specify multiple calculation processes on
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systems with more than one CPU.
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For additional options, consult the
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.I rtrace(1)
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man page.
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The final
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.I octree
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argument must be given, as the octree cannot be read from the
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standard input.
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.SH EXAMPLES
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To compute values for the same sensor with two different positions:
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.IP "" .2i
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rsensor -ab 2 -vf posA.vf mysens.dat -vf posB.vf mysens.dat scene.oct
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.PP
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To generate a set of rays corresponding to a given sensor and compute
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the resulting signal with rtrace:
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.IP "" .2i
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rsensor -h -vf posC.vf mysens.dat . | rtrace -h scene.oct | total -m
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.SH ENVIRONMENT
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RAYPATH the directories to check for auxiliary files.
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.SH AUTHOR
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Greg Ward for Architectural Energy Corporation
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.SH "SEE ALSO"
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oconv(1), rpict(1), rcontrib(1), rtrace(1)
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