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 detection 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 fraction 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 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 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 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 rendered 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 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  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 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)