NAME

       pmdblur - generate views for combined camera motion and depth blurring

SYNOPSIS

       pmdblur speed aperture nsamp v0file v1file

DESCRIPTION

       Pmdblur  takes  two  viewfiles  and  generates nsamp views starting from v0file and moving
       towards v1file, simulating an aperture of diameter aperture  in  world  coordinate  units.
       When  rendered and averaged together, these views will result in a picture with motion and
       depth-of-field 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  pmdblur  provides supplemental view
       specifications only.)

       For pinterp, feed the output of pmdblur 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  pmdblur 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  pmdblur.   We  have  found  a  nsamp setting somewhere between 7 and 15 to be
       adequate for most images.  Relatively larger values  are  appropriate  for  faster  camera
       motion.

       The -pm and/or -pd options 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 pmdblur 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 samples, and the -pd option equal to the aperture divided by  the  number
       of  samples.   This  will  be  just  enough to blur the boundaries of the ghosts which may
       appear using pmdblur with a small number of time samples.

       To simulate a particular camera's aperture, divide the focal length of the lens by the  f-
       number,  then  convert  to  the corresponding world coordinate units.  For example, if you
       wish to simulate a 50mm lens at f/2.0 in a scene modeled in meters, then you  divide  50mm
       by 2.0 to get 25mm, which corresponds to an effective aperture of 0.025 meters.

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 with  an  aperture  of
       0.1 world units:

         pmdblur  .25  .1  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

SEE ALSO

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