Radiance pdfblur program

PDFBLUR(1)                                                          PDFBLUR(1)

NAME

       pdfblur - generate views for depth-of-field blurring

SYNOPSIS

       pdfblur aperture nsamp viewfile

DESCRIPTION

       Pdfblur  takes  the given viewfile and computes nsamp views based on an
       aperture diameter of aperture (in world coordinate units) and  a  focal
       distance  equal  to  the length of the -vd view direction vector.  When
       rendered and averaged together, these views will result  in  a  picture
       with  the  specified depth of field.  Either pinterp(1) or rpict(1) may
       be called to do the actual work.  (The  given  viewfile  must  also  be
       passed  on  the command line to the chosen renderer, since pdfblur pro-
       vides supplemental view specifications only.)

       For pinterp, feed the output of pdfblur to the standard input  of  pin-
       terp  and apply the -B option to blur views together.  In most cases, a
       single picture with z-buffer is all that is required to get a satisfac-
       tory  result, though the perfectionist may wish to apply three pictures
       arranged in a triangle about the aperature, or alternatively apply  the
       -ff  option  together  with the -fr option of pinterp.  (The latter may
       actually work out to be faster, since rendering three views takes three
       times  as  long as a single view, and the -fr option will end up recom-
       puting relatively few pixels by comparison.)

       To use pdfblur with rpict, apply the -S option to indicate a  rendering
       sequence, and set the -o option with a formatted file name to save mul-
       tiple 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 pdfblur.  We have  found  a  nsamp  setting
       somewhere  between 5 and 10 to be adequate for most images.  Relatively
       larger values are appropriate for larger aperatures.

       The -pd option of rpict may be used instead or in combination  with  or
       instead  of pdfblur to blur depth-of-field.  If used in combination, it
       is best to set the -pd option to the overall aperture divided by  nsamp
       to minimize ghosting in the output.

       To  simulate a particular camera's aperture, divide the focal length of
       the lens by the f-number, then convert to the corresponding world coor-
       dinate  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 an aperture of 0.5 inches on a lens focused
       at a distance of 57 inches:

         rpict -vf myview -x 640 -y 480 -z orig.zbf scene.oct > orig.hdr
         pdfblur 0.5 57 8 orig.hdr | pinterp -B -vf orig.hdr  -x  640  -y  480
         orig.hdr orig.zbf > blurry.hdr

       To use rpict exclusively to do the same:

         pdfblur  .5  57  5  myview  |  rpict -S 1 -vf myview -x 640 -y 480 -o
         view%d.hdr scene.oct
         pcomb -s .2 view1.hdr -s .2 view2.hdr -s .2 view3.hdr -s .2 view4.hdr
         -s .2 view5.hdr > blurry.hdr

AUTHOR

       Greg Ward

BUGS

       This program really only works with perspective views.

SEE ALSO

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

RADIANCE                            1/24/96                         PDFBLUR(1)