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)