NAME

       pmblur - generate views for camera motion blurring

SYNOPSIS

       pmblur speed nsamp v0file v1file

DESCRIPTION

       Pmblur  takes  two  viewfiles  and  generates  nsamp views starting from v0file and moving
       towards v1file.  When rendered and averaged together, these views will result in a picture
       with  motion  blur  due  to  a camera changing from v0 to v1 in a relative time unit of 1,
       whose shutter is open starting at v0 for speed of these time units.  Either pinterp(1)  or
       rpict(1)  may  be  called to do the actual work.  (The given v0file must also be passed on
       the command  line  to  the  chosen  renderer,  since  pmblur  provides  supplemental  view
       specifications only.)

       For  pinterp,  feed the output of pmblur to the standard input of pinterp and apply the -B
       option to blur views together.  In most cases, two pictures with z-buffers at  v0  and  v1
       will  get a satisfactory result, though the perfectionist may wish to apply the -ff option
       together with the -fr option of pinterp.

       To use pmblur with rpict, apply the -S option to indicate a rendering  sequence,  and  set
       the  -o  option with a formatted file name to save multiple output pictures.  When all the
       renderings are finished,  combine  them  with  the  pcomb(1)  program,  using  appropriate
       scalefactors  to  achieve  an  average.  Note that using rpict is MUCH more expensive than
       using pinterp, and it is only recommended if the scene and application  absolutely  demand
       it (e.g. there is prominent refraction that must be modeled accurately).

       For  both  pinterp  and  rpict, the computation time will be proportional to the number of
       views from pmblur.  We have found a nsamp  setting  somewhere  between  5  and  10  to  be
       adequate  for  most  images.   Relatively  larger values are appropriate for faster camera
       motion.

       The -pm option of rpict may be used instead or in combination  to  blur  animated  frames,
       with the added advantage of blurring reflections and refractions according to their proper
       motion.  However, this option will result in more noise and expense than using pmblur with
       pinterp  as  a post-process.  If both blurring methods are used, a smaller value should be
       given to the rpict -pm option equal to the shutter speed divided by the number  of  pmblur
       views.   This  will  be  just enough to blur the boundaries of the ghosts which may appear
       using pmblur with a small number of time samples.

EXAMPLES

       To use pinterp to simulate motion blur between two frames  of  a  walk-through  animation,
       where the camera shutter is open for 1/4 of the interframe distance:

         pmblur  .25 8 fr1023.hdr fr1024.hdr | pinterp -B -vf fr1023.hdr -x 640 -y 480 fr1023.hdr
         fr1023.zbf fr1024.hdr fr1024.zbf > fr1023b.hdr

AUTHOR

       Greg Ward

BUGS

       Changes in the view shift and lift vectors or the fore and aft  clipping  planes  are  not
       blurred.

SEE ALSO

       pcomb(1), pdfblur(1), pinterp(1), pmdblur(1), rcalc(1), rpict(1), vwright(1)