1 .\" RCSid "$Id: pmblur.1,v 1.5 2008/11/10 19:08:17 greg Exp $"

     2 .TH PMBLUR 1 3/3/98 RADIANCE

     3 .SH NAME

     4 pmblur - generate views for camera motion blurring

     5 .SH SYNOPSIS

     6 .B pmblur

     7 .B speed

     8 .B nsamp

     9 .B v0file

    10 .B v1file

    11 .SH DESCRIPTION

    12 .I Pmblur

    13 takes two viewfiles and generates

    14 .I nsamp

    15 views starting from

    16 .I v0file

    17 and moving towards

    18 .I v1file.

    19 When rendered and averaged together, these views will result in

    20 a picture with motion blur due to a camera changing from v0 to v1

    21 in a relative time unit of 1, whose shutter is open starting at v0 for

    22 .I speed

    23 of these time units.

    24 Either

    25 .I pinterp(1)

    26 or

    27 .I rpict(1)

    28 may be called to do the actual work.

    29 (The given

    30 .I v0file

    31 must also be passed on the command line to the chosen renderer, since

    32 .I pmblur

    33 provides supplemental view specifications only.)\0

    34 .PP

    35 For

    36 .I pinterp,

    37 feed the output of

    38 .I pmblur

    39 to the standard input of

    40 .I pinterp

    41 and apply the

    42 .I \-B

    43 option to blur views together.

    44 In most cases, two pictures with z-buffers at v0 and v1 will

    45 get a satisfactory result, though the perfectionist may wish to

    46 apply the

    47 .I \-ff

    48 option together with the

    49 .I \-fr

    50 option of

    51 .I pinterp.

    52 .PP

    53 To use

    54 .I pmblur

    55 with

    56 .I rpict,

    57 apply the

    58 .I \-S

    59 option to indicate a rendering sequence, and set the

    60 .I \-o

    61 option with a formatted file name to save multiple output

    62 pictures.

    63 When all the renderings are finished, combine them with the

    64 .I pcomb(1)

    65 program, using appropriate scalefactors to achieve an average.

    66 Note that using

    67 .I rpict

    68 is MUCH more expensive than using

    69 .I pinterp,

    70 and it is only recommended if the scene and application

    71 absolutely demand it (e.g. there is prominent refraction that

    72 must be modeled accurately).

    73 .PP

    74 For both

    75 .I pinterp

    76 and

    77 .I rpict,

    78 the computation time will be proportional to the number of views from

    79 .I pmblur.

    80 We have found a

    81 .I nsamp

    82 setting somewhere between 5 and 10 to be adequate for most images.

    83 Relatively larger values are appropriate for faster camera motion.

    84 .PP

    85 The

    86 .I \-pm

    87 option of

    88 .I rpict

    89 may be used instead or in combination to blur animated frames, with

    90 the added advantage of blurring reflections and refractions according

    91 to their proper motion.

    92 However, this option will result in more noise and expense than using

    93 .I pmblur

    94 with

    95 .I pinterp

    96 as a post-process.

    97 If both blurring methods are used, a smaller value should be given to the

    98 .I rpict

    99 .I \-pm

   100 option equal to the shutter speed divided by the number of pmblur views.

   101 This will be just enough to blur the boundaries of the ghosts

   102 which may appear using

   103 .I pmblur

   104 with a small number of time samples.

   105 .SH EXAMPLES

   106 To use

   107 .I pinterp

   108 to simulate motion blur between two frames of a walk-through

   109 animation, where the camera shutter is open for 1/4 of the

   110 interframe distance:

   111 .IP "" .2i

   112 pmblur .25 8 fr1023.hdr fr1024.hdr | pinterp \-B \-vf fr1023.hdr \-x 640 \-y 480

   113 fr1023.hdr fr1023.zbf fr1024.hdr fr1024.zbf > fr1023b.hdr

   114 .SH AUTHOR

   115 Greg Ward

   116 .SH BUGS

   117 Changes in the view shift and lift vectors or the fore and aft

   118 clipping planes are not blurred.

   119 .SH "SEE ALSO"

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