xenial (1) pdfblur.1.gz

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  provides  supplemental  view
       specifications only.)

       For pinterp, feed the output of pdfblur to the standard input of pinterp 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
       satisfactory 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 recomputing 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 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
       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 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 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)