RPICT(1) General Commands Manual RPICT(1)
rpict - generate a RADIANCE picture
rpict [ options ] [ $EVAR ] [ @file ] [ octree ]
rpict [ options ] -defaults
Rpict generates a picture from the RADIANCE scene given in octree and sends it to the standard output. If no octree is given, the standard
input is read. (The octree may also be specified as the output of a command enclosed in quotes and preceded by a `!'.) Options specify
the viewing parameters as well as giving some control over the calculation. Options may be given on the command line and/or read from the
environment and/or read from a file. A command argument beginning with a dollar sign ('$') is immediately replaced by the contents of the
given environment variable. A command argument beginning with an at sign ('@') is immediately replaced by the contents of the given file.
In the second form shown above, the default values for the options (modified by those options present) are printed with a brief explana-
Most options are followed by one or more arguments, which must be separated from the option and each other by white space. The exceptions
to this rule are the -vt option and the boolean options. Normally, the appearance of a boolean option causes a feature to be "toggled",
that is switched from off to on or on to off depending on its previous state. Boolean options may also be set explicitly by following them
immediately with a '+' or '-', meaning on or off, respectively. Synonyms for '+' are any of the characters "yYtT1", and synonyms for '-'
are any of the characters "nNfF0". All other characters will generate an error.
-vtt Set view type to t. If t is 'v', a perspective view is selected. If t is 'l', a parallel view is used. A cylindrical panorma
may be selected by setting t to the letter 'c'. This view is like a standard perspective vertically, but projected on a cylinder
horizontally (like a soupcan's-eye view). Three fisheye views are provided as well; 'h' yields a hemispherical fisheye view, 'a'
results in angular fisheye distortion, and 's' results in a planisphere (stereographic) projection. A hemispherical fisheye is a
projection of the hemisphere onto a circle. The maximum view angle for this type is 180 degrees. An angular fisheye view is
defined such that distance from the center of the image is proportional to the angle from the central view direction. An angular
fisheye can display a full 360 degrees. A planisphere fisheye view maintains angular relationships between lines, and is com-
monly used for sun path analysis. This is more commonly known as a "stereographic projection," but we avoid the term here so as
not to confuse it with a stereoscopic pair. A planisphere fisheye can display up to (but not including) 360 degrees, although
distortion becomes extreme as this limit is approached. Note that there is no space between the view type option and its single
-vp x y z Set the view point to x y z . This is the focal point of a perspective view or the center of a parallel projection.
-vd xd yd zd
Set the view direction vector to xd yd zd . The length of this vector indicates the focal distance as needed by the -pd option,
-vu xd yd zd
Set the view up vector (vertical direction) to xd yd zd .
-vh val Set the view horizontal size to val. For a perspective projection (including fisheye views), val is the horizontal field of view
(in degrees). For a parallel projection, val is the view width in world coordinates.
-vv val Set the view vertical size to val.
-vo val Set the view fore clipping plane at a distance of val from the view point. The plane will be perpendicular to the view direction
for perspective and parallel view types. For fisheye view types, the clipping plane is actually a clipping sphere, centered on
the view point with radius val. Objects in front of this imaginary surface will not be visible. This may be useful for seeing
through walls (to get a longer perspective from an exterior view point) or for incremental rendering. A value of zero implies no
foreground clipping. A negative value produces some interesting effects, since it creates an inverted image for objects behind
the viewpoint. This possibility is provided mostly for the purpose of rendering stereographic holograms.
-va val Set the view aft clipping plane at a distance of val from the view point. Like the view fore plane, it will be perpendicular to
the view direction for perspective and parallel view types. For fisheye view types, the clipping plane is actually a clipping
sphere, centered on the view point with radius val. Objects behind this imaginary surface will not be visible. A value of zero
means no aft clipping, and is the only way to see infinitely distant objects such as the sky.
-vs val Set the view shift to val. This is the amount the actual image will be shifted to the right of the specified view. This is
option is useful for generating skewed perspectives or rendering an image a piece at a time. A value of 1 means that the ren-
dered image starts just to the right of the normal view. A value of -1 would be to the left. Larger or fractional values are
permitted as well.
-vl val Set the view lift to val. This is the amount the actual image will be lifted up from the specified view, similar to the -vs
-vf file Get view parameters from file, which may be a picture or a file created by rvu (with the "view" command).
-x res Set the maximum x resolution to res.
-y res Set the maximum y resolution to res.
-pa rat Set the pixel aspect ratio (height over width) to rat. Either the x or the y resolution will be reduced so that the pixels have
this ratio for the specified view. If rat is zero, then the x and y resolutions will adhere to the given maxima.
-ps size Set the pixel sample spacing to the integer size. This specifies the sample spacing (in pixels) for adaptive subdivision on the
-pt frac Set the pixel sample tolerance to frac. If two samples differ by more than this amount, a third sample is taken between them.
-pj frac Set the pixel sample jitter to frac. Distributed ray-tracing performs anti-aliasing by randomly sampling over pixels. A value
of one will randomly distribute samples over full pixels. A value of zero samples pixel centers only. A value between zero and
one is usually best for low-resolution images.
-pm frac Set the pixel motion blur to frac. In an animated sequence, the exact view will be blurred between the previous view and the
next view as though a shutter were open this fraction of a frame time. (See the -S option regarding animated sequences.) The
first view will be blurred according to the difference between the initial view set on the command line and the first view taken
from the standard input. It is not advisable to use this option in combination with the pmblur(1) program, since one takes the
place of the other. However, it may improve results with pmblur to use a very small fraction with the -pm option, to avoid the
ghosting effect of too few time samples.
-pd dia Set the pixel depth-of-field aperture to a diameter of dia (in world coordinates). This will be used in conjunction with the
view focal distance, indicated by the length of the view direction vector given in the -vd option. It is not advisable to use
this option in combination with the pdfblur(1) program, since one takes the place of the other. However, it may improve results
with pdfblur to use a very small fraction with the -pd option, to avoid the ghosting effect of too few samples.
-dj frac Set the direct jittering to frac. A value of zero samples each source at specific sample points (see the -ds option below), giv-
ing a smoother but somewhat less accurate rendering. A positive value causes rays to be distributed over each source sample
according to its size, resulting in more accurate penumbras. This option should never be greater than 1, and may even cause
problems (such as speckle) when the value is smaller. A warning about aiming failure will issued if frac is too large. It is
usually wise to turn off image sampling when using direct jitter by setting -ps to 1.
-ds frac Set the direct sampling ratio to frac. A light source will be subdivided until the width of each sample area divided by the dis-
tance to the illuminated point is below this ratio. This assures accuracy in regions close to large area sources at a slight
computational expense. A value of zero turns source subdivision off, sending at most one shadow ray to each light source.
-dt frac Set the direct threshold to frac. Shadow testing will stop when the potential contribution of at least the next and at most all
remaining light source samples is less than this fraction of the accumulated value. (See the -dc option below.) The remaining
light source contributions are approximated statistically. A value of zero means that all light source samples will be tested
-dc frac Set the direct certainty to frac. A value of one guarantees that the absolute accuracy of the direct calculation will be equal
to or better than that given in the -dt specification. A value of zero only insures that all shadow lines resulting in a con-
trast change greater than the -dt specification will be calculated.
-dr N Set the number of relays for secondary sources to N. A value of 0 means that secondary sources will be ignored. A value of 1
means that sources will be made into first generation secondary sources; a value of 2 means that first generation secondary
sources will also be made into second generation secondary sources, and so on.
-dp D Set the secondary source presampling density to D. This is the number of samples per steradian that will be used to determine
ahead of time whether or not it is worth following shadow rays through all the reflections and/or transmissions associated with a
secondary source path. A value of 0 means that the full secondary source path will always be tested for shadows if it is tested
-dv Boolean switch for light source visibility. With this switch off, sources will be black when viewed directly although they will
still participate in the direct calculation. This option may be desirable in conjunction with the -i option so that light
sources do not appear in the output.
-ss samp Set the specular sampling to samp. For values less than 1, this is the degree to which the highlights are sampled for rough
specular materials. A value greater than one causes multiple ray samples to be sent to reduce noise at a commmesurate cost. A
value of zero means that no jittering will take place, and all reflections will appear sharp even when they should be diffuse.
This may be desirable when used in combination with image sampling (see -ps option above) to obtain faster renderings.
-st frac Set the specular sampling threshold to frac. This is the minimum fraction of reflection or transmission, under which no specular
sampling is performed. A value of zero means that highlights will always be sampled by tracing reflected or transmitted rays. A
value of one means that specular sampling is never used. Highlights from light sources will always be correct, but reflections
from other surfaces will be approximated using an ambient value. A sampling threshold between zero and one offers a compromise
between image accuracy and rendering time.
-bv Boolean switch for back face visibility. With this switch off, back faces of opaque objects will be invisible to all rays. This
is dangerous unless the model was constructed such that all surface normals on opaque objects face outward. Although turning off
back face visibility does not save much computation time under most circumstances, it may be useful as a tool for scene debug-
ging, or for seeing through one-sided walls from the outside. This option has no effect on transparent or translucent materials.
-av red grn blu
Set the ambient value to a radiance of red grn blu . This is the final value used in place of an indirect light calculation. If
the number of ambient bounces is one or greater and the ambient value weight is non-zero (see -aw and -ab below), this value may
be modified by the computed indirect values to improve overall accuracy.
-aw N Set the relative weight of the ambient value given with the -av option to N. As new indirect irradiances are computed, they will
modify the default ambient value in a moving average, with the specified weight assigned to the initial value given on the com-
mand and all other weights set to 1. If a value of 0 is given with this option, then the initial ambient value is never modi-
fied. This is the safest value for scenes with large differences in indirect contributions, such as when both indoor and outdoor
(daylight) areas are visible.
-ab N Set the number of ambient bounces to N. This is the maximum number of diffuse bounces computed by the indirect calculation. A
value of zero implies no indirect calculation.
-ar res Set the ambient resolution to res. This number will determine the maximum density of ambient values used in interpolation.
Error will start to increase on surfaces spaced closer than the scene size divided by the ambient resolution. The maximum ambi-
ent value density is the scene size times the ambient accuracy (see the -aa option below) divided by the ambient resolution. The
scene size can be determined using getinfo(1) with the -d option on the input octree. A value of zero is interpreted as unlim-
-aa acc Set the ambient accuracy to acc. This value will approximately equal the error from indirect illuminance interpolation. A value
of zero implies no interpolation.
-ad N Set the number of ambient divisions to N. The error in the Monte Carlo calculation of indirect illuminance will be inversely
proportional to the square root of this number. A value of zero implies no indirect calculation.
-as N Set the number of ambient super-samples to N. Super-samples are applied only to the ambient divisions which show a significant
-af fname Set the ambient file to fname. This is where indirect illuminance will be stored and retrieved. Normally, indirect illuminance
values are kept in memory and lost when the program finishes or dies. By using a file, different invocations can share illumi-
nance values, saving time in the computation. Also, by creating an ambient file during a low resolution rendering, better
results can be obtained in a second high resolution pass. The ambient file is in a machine-independent binary format which may
be examined with lookamb(1).
The ambient file may also be used as a means of communication and data sharing between simultaneously executing processes. The
same file may be used by multiple processes, possibly running on different machines and accessing the file via the network (ie.
nfs(4)). The network lock manager lockd(8) is used to insure that this information is used consistently.
If any calculation parameters are changed or the scene is modified, the old ambient file should be removed so that the calcula-
tion can start over from scratch. For convenience, the original ambient parameters are listed in the header of the ambient file.
Getinfo(1) may be used to print out this information.
-ae mod Append mod to the ambient exclude list, so that it will not be considered during the indirect calculation. This is a hack for
speeding the indirect computation by ignoring certain objects. Any object having mod as its modifier will get the default ambi-
ent level rather than a calculated value. Any number of excluded modifiers may be given, but each must appear in a separate
-ai mod Add mod to the ambient include list, so that it will be considered during the indirect calculation. The program can use either
an include list or an exclude list, but not both.
-aE file Same as -ae, except read modifiers to be excluded from file. The RAYPATH environment variable determines which directories are
searched for this file. The modifier names are separated by white space in the file.
-aI file Same as -ai, except read modifiers to be included from file.
-me rext gext bext
Set the global medium extinction coefficient to the indicated color, in units of 1/distance (distance in world coordinates).
Light will be scattered or absorbed over distance according to this value. The ratio of scattering to total scattering plus
absorption is set by the albedo parameter, described below.
-ma ralb galb balb
Set the global medium albedo to the given value between 0 0 0 and 1 1 1. A zero value means that all light not transmitted by
the medium is absorbed. A unitary value means that all light not transmitted by the medium is scattered in some new direction.
The isotropy of scattering is determined by the Heyney-Greenstein parameter, described below.
-mg gecc Set the medium Heyney-Greenstein eccentricity parameter to gecc. This parameter determines how strongly scattering favors the
forward direction. A value of 0 indicates perfectly isotropic scattering. As this parameter approaches 1, scattering tends to
prefer the forward direction.
Set the medium sampling distance to sampdist, in world coordinate units. During source scattering, this will be the average dis-
tance between adjacent samples. A value of 0 means that only one sample will be taken per light source within a given scattering
-i Boolean switch to compute irradiance rather than radiance values. This only affects the final result, substituting a Lambertian
surface and multiplying the radiance by pi. Glass and other transparent surfaces are ignored during this stage. Light sources
still appear with their original radiance values, though the -dv option (above) may be used to override this.
-u Boolean switch to control uncorrelated random sampling. When "off", a low-discrepancy sequence is used, which reduces variance
but can result in a brushed appearance in specular highlights. When "on", pure Monte Carlo sampling is used in all calculations.
-lr N Limit reflections to a maximum of N, if N is a positive integer. If N is zero, then Russian roulette is used for ray termina-
tion, and the -lw setting (below) must be positive. If N is a negative integer, then this sets the upper limit of reflections
past which Russian roulette will be used. In scenes with dielectrics and total internal reflection, a setting of 0 (no limit)
may cause a stack overflow.
-lw frac Limit the weight of each ray to a minimum of frac. During ray-tracing, a record is kept of the estimated contribution (weight) a
ray would have in the image. If this weight is less than the specified minimum and the -lr setting (above) is positive, the ray
is not traced. Otherwise, Russian roulette is used to continue rays with a probability equal to the ray weight divided by the
Instead of generating a single picture based only on the view parameters given on the command line, this option causes rpict to
read view options from the standard input and for each line containing a valid view specification, generate a corresponding pic-
ture. This option is most useful for generating animated sequences, though it may also be used to control rpict from a remote
process for network-distributed rendering. Seqstart is a positive integer that will be associated with the first output frame,
and incremented for successive output frames. By default, each frame is concatenated to the output stream, but it is possible to
change this action using the -o option (described below). Multiple frames may be later extracted from the output using
Note that the octree may not be read from the standard input when using this option.
-o fspec Send the picture(s) to the file(s) given by fspec instead of the standard output. If this option is used in combination with -S
and fspec contains an integer field for printf(3) (eg. "%03d") then the actual output file name will include the current frame
number. Rpict will not allow a picture file to be clobbered (overwritten) with this option. If an image in a sequence already
exists (-S option), rpict will skip until it reaches an image that doesn't, or the end of the sequence. This is useful for run-
ning rpict on multiple machines or processors to render the same sequence, as each process will skip to the next frame that needs
-r fn Recover pixel information from the file fn. If the program gets killed during picture generation, the information may be recov-
ered using this option. The view parameters and picture dimensions are also recovered from fn if possible. The other options
should be identical to those which created fn, or an inconsistent picture may result. If fn is identical to the file specifica-
tion given with the -o option, rpict will rename the file prior to copying its contents. This insures that the old file is not
overwritten accidentally. (See also the -ro option, below.)
If fn is an integer and the recover option is used in combination with the -S option, then rpict skips a number of view specifi-
cations on its input equal to the difference between fn and seqstart. Rpict then performs a recovery operation on the file con-
structed from the frame number fn and the output file specification given with the -o option. This provides a convenient mecha-
nism for recovering in the middle of an aborted picture sequence.
The recovered file will be removed if the operation is successful. If the recover operation fails (due to lack of disk space)
and the output file and recover file specifications are the same, then the original information may be left in a renamed tempo-
rary file. (See FILES section, below.)
-ro fspec This option causes pixel information to be recovered from and subsequently returned to the picture file fspec. The effect is the
same as specifying identical recover and output file names with the -r and -o options.
-z fspec Write pixel distances out to the file fspec. The values are written as short floats, one per pixel in scanline order, as
required by pinterp(1). Similar to the -o option, the actual file name will be constructed using printf and the frame number
from the -S option. If used with the -r option, -z also recovers information from an aborted rendering.
-P pfile Execute in a persistent mode, using pfile as the control file. This option must be used together with -S, and is incompatible
with the recover option (-r). Persistent execution means that after reaching end-of-file on its input, rpict will fork a child
process that will wait for another rpict command with the same -P option to attach to it. (Note that since the rest of the com-
mand line options will be those of the original invocation, it is not necessary to give any arguments besides -P for subsequent
calls.) Killing the process is achieved with the kill(1) command. (The process ID in the first line of pfile may be used to
identify the waiting rpict process.) This option may be less useful than the -PP variation, explained below.
-PP pfile Execute in continuous-forking persistent mode, using pfile as the control file. The difference between this option and the -P
option described above is the creation of multiple duplicate processes to handle any number of attaches. This provides a simple
and reliable mechanism of memory sharing on most multiprocessing platforms, since the fork(2) system call will share memory on a
copy-on-write basis. This option may be used with rpiece(1) to efficiently render a single image using multiple processors on
the same host.
-t sec Set the time between progress reports to sec. A progress report writes the number of rays traced, the percentage completed, and
the CPU usage to the standard error. Reports are given either automatically after the specified interval, or when the process
receives a continue (-CONT) signal (see kill(1)). A value of zero turns automatic reporting off.
-e efile Send error messages and progress reports to efile instead of the standard error.
-w Boolean switch for warning messages. The default is to print warnings, so the first appearance of this option turns them off.
rpict -vp 10 5 3 -vd 1 -.5 0 scene.oct > scene.hdr
rpict -S 1 -o frame%02d.hdr scene.oct < keyframes.vf
RAYPATH the directories to check for auxiliary files.
/tmp/rtXXXXXX common header information for picture sequence
rfXXXXXX temporary name for recover file
If the program terminates from an input related error, the exit status will be 1. A system related error results in an exit status of 2.
If the program receives a signal that is caught, it will exit with a status of 3. In each case, an error message will be printed to the
standard error, or to the file designated by the -e option.
getinfo(1), lookamb(1), oconv(1), pdfblur(1), pfilt(1), pinterp(1), pmblur(1), printf(3), ra_rgbe(1), rad(1), rtrace(1), rvu(1)