rhpict
Radiance rhpict program
RHPICT(1) RHPICT(1)
NAME
rhpict - render a RADIANCE picture from a holodeck file
SYNOPSIS
rhpict [ options ] holodeck
DESCRIPTION
Rhpict generates one or more pictures from the RADIANCE holodeck file
holodeck and sends them to the standard output. The -o option may be
used to specify an alternate output file. Other options specify the
viewing parameters and provide some control over the calculation.
The view as well as some of the other controls are shared in common
with the rpict(1) command. The options that are unique to rhpict are
given first, followed by the more familiar ones.
-s Use the smooth resampling algorithm, which amounts to linear
interpolation between ray samples with additional edge detec-
tion along color and object boundaries. This is the default.
-r rf Use random resampling, where rf is a fraction from 0 to 1
indicating the desired degree of randomness. A random frac-
tion of 0 is not the same as smooth resampling, because there
is no linear interpolation, just Voronoi regions. Values
greater than 1 produce interesting underwater effects.
-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.
-pe expval
Set the exposure value for the output pictures to expval.
Since filtering is performed by rhpict, there is little sense
in passing the output through pfilt(1), other than changing
the exposure. This option eliminates that need. The value
may be specified either as a multiplier, or as a number f-
stops preceeded by a '+' or '-' character.
-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 cylindri-
cal panorma may be selected by setting t to the letter 'c'.
This view is like a standard perspective vertically, but pro-
jected 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 fish-
eye can display a full 360 degrees. A planisphere fisheye
view maintains angular relationships between lines, and is
commonly 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 letter argument.
-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 .
-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 pro-
jection (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 fish-
eye 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 per-
spective from an exterior view point) or for incremental ren-
dering. 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 ren-
dering 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 perpendicu-
lar to the view direction for perspective and parallel view
types. For fisheye view types, the clipping plane is actu-
ally 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 rendered image starts just to the right of the nor-
mal 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 option.
-vf file Get view parameters from file, which may be a picture or a
file created by rvu (with the "view" command).
-S seqstart
Instead of generating a single picture based only on the view
parameters given on the command line, this option causes
rhpict to read view options from the standard input and for
each line containing a valid view specification, generate a
corresponding picture. Seqstart is a positive integer that
will be associated with the first output frame, and incre-
mented 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 a single output
stream using the ra_rgbe(1) command.
-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.
-w Turn off warning messages.
EXAMPLE
rhpict -vp 10 5 3 -vd 1 -.5 0 scene.hdk > scene.hdr
rpict -S 1 -o frame%02d.hdr scene.hdk < keyframes.vf
AUTHOR
Greg Ward
SEE ALSO
getinfo(1), pfilt(1), pinterp(1), printf(3), ra_rgbe(1), rholo(1),
rpict(1), rvu(1)
RADIANCE 3/10/99 RHPICT(1)
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– last modified
Nov 09, 2019 09:22 AM