1 .\" RCSid "$Id: pmdblur.1,v 1.4 2008/11/10 19:08:17 greg Exp $"

     2 .TH PMDBLUR 1 1/17/05 RADIANCE

     3 .SH NAME

     4 pmdblur - generate views for combined camera motion and depth blurring

     5 .SH SYNOPSIS

     6 .B pmdblur

     7 .B speed

     8 .B aperture

     9 .B nsamp

    10 .B v0file

    11 .B v1file

    12 .SH DESCRIPTION

    13 .I Pmdblur

    14 takes two viewfiles and generates

    15 .I nsamp

    16 views starting from

    17 .I v0file

    18 and moving towards

    19 .I v1file,

    20 simulating an aperture of diameter

    21 .I aperture

    22 in world coordinate units.

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

    24 a picture with motion and depth-of-field

    25 blur due to a camera changing from v0 to v1

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

    27 .I speed

    28 of these time units.

    29 Either

    30 .I pinterp(1)

    31 or

    32 .I rpict(1)

    33 may be called to do the actual work.

    34 (The given

    35 .I v0file

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

    37 .I pmdblur

    38 provides supplemental view specifications only.)\0

    39 .PP

    40 For

    41 .I pinterp,

    42 feed the output of

    43 .I pmdblur

    44 to the standard input of

    45 .I pinterp

    46 and apply the

    47 .I \-B

    48 option to blur views together.

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

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

    51 apply the

    52 .I \-ff

    53 option together with the

    54 .I \-fr

    55 option of

    56 .I pinterp.

    57 .PP

    58 To use

    59 .I pmdblur

    60 with

    61 .I rpict,

    62 apply the

    63 .I \-S

    64 option to indicate a rendering sequence, and set the

    65 .I \-o

    66 option with a formatted file name to save multiple output

    67 pictures.

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

    69 .I pcomb(1)

    70 program, using appropriate scalefactors to achieve an average.

    71 Note that using

    72 .I rpict

    73 is MUCH more expensive than using

    74 .I pinterp,

    75 and it is only recommended if the scene and application

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

    77 must be modeled accurately).

    78 .PP

    79 For both

    80 .I pinterp

    81 and

    82 .I rpict,

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

    84 .I pmdblur.

    85 We have found a

    86 .I nsamp

    87 setting somewhere between 7 and 15 to be adequate for most images.

    88 Relatively larger values are appropriate for faster camera motion.

    89 .PP

    90 The

    91 .I \-pm

    92 and/or

    93 .I \-pd

    94 options of

    95 .I rpict

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

    97 the added advantage of blurring reflections and refractions according

    98 to their proper motion.

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

   100 .I pmdblur

   101 with

   102 .I pinterp

   103 as a post-process.

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

   105 .I rpict

   106 .I \-pm

   107 option equal to the shutter speed divided by the number of samples, and the

   108 .I \-pd

   109 option equal to the aperture divided by the number of samples.

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

   111 which may appear using

   112 .I pmdblur

   113 with a small number of time samples.

   114 .PP

   115 To simulate a particular camera's aperture, divide the focal length of

   116 the lens by the f-number, then convert to the corresponding

   117 world coordinate units.

   118 For example, if you wish to simulate a 50mm lens at f/2.0 in

   119 a scene modeled in meters, then you divide 50mm by 2.0 to get 25mm,

   120 which corresponds to an effective aperture of 0.025 meters.

   121 .SH EXAMPLES

   122 To use

   123 .I pinterp

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

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

   126 interframe distance with an aperture of 0.1 world units:

   127 .IP "" .2i

   128 pmdblur .25 .1 8 fr1023.hdr fr1024.hdr | pinterp \-B \-vf fr1023.hdr \-x 640 \-y 480

   129 fr1023.hdr fr1023.zbf fr1024.hdr fr1024.zbf > fr1023b.hdr

   130 .SH AUTHOR

   131 Greg Ward

   132 .SH "SEE ALSO"

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