RHPICT(1)						      General Commands Manual							 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 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 pass-
		 ing 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 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
		 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 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
		 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 pic-
		 ture.	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)

RADIANCE
							      3/10/99								 RHPICT(1)