man/man1/vwrays.1

.\" RCSid "$Id"
.TH VWRAYS 1 1/15/99 RADIANCE
.SH NAME
vwrays - compute rays for a given picture or view
.SH SYNOPSIS
.B vwrays
.B "[ -i -f{a|f|d} | -d ]"
{
.B "view opts .."
|
.B picture
.B [zbuf]
}
.SH DESCRIPTION
.I Vwrays
takes a picture or view specification and computes the ray origin and
direction corresponding to each pixel in the image.
This information may then be passed to
.I rtrace(1)
to perform other calculations.
If a given pixel has no corresponding ray (because it is outside the
legal view boundaries), then six zero values are sent instead.
.PP
The
.I -i
option may be used to specify desired pixel positions on the standard
input rather than generating all the pixels for a given view.
.PP
The
.I -f
option may be used to set the record format to something other than the
default ASCII.
Using raw float or double records for example can reduce the time
requirements of transferring and interpreting information in
.I rtrace.
.PP
View options may be any combination of standard view parameters described
in the
.I rpict(1)
manual page, including input from a view file with the
.I \-vf
option.
Additionally, the target X and Y dimensions may be specified with
.I -x
and
.I -y
options, and the pixel aspect ratio may be given with
.I -p.
The default dimensions are 512x512, with a pixel aspect ratio of 1.0.
Just as in
.I rpict,
the X or the Y dimension will be reduced if necessary
to best match the specified pixel
aspect ratio, unless this ratio is set to zero.
.PP
If the
.I -d
option is given, then
.I vwrays
just prints the computed image dimensions, which are based on the view
aspect and the pixel aspect ratio just described.
The
.I -ld
switch will also be printed, with
.I -ld+
if the view file has an aft clipping plane, and
.I -ld-
otherwise.
This is useful for passing options to the
.I rtrace
command line.
(See below.)
.PP
If the view contains an aft clipping plane
.I (-va
option), then the magnitudes of the ray directions will
equal the maximum distance for each pixel, which will be interpreted
correctly by
.I rtrace
with the
.I -ld+
option.
Note that this option should not be given unless there is an aft
clipping plane, since the ray direction vectors will be normalized
otherwise, which would produce a uniform clipping distance of 1.
.PP
If a picture is given on the command line rather than a set of view options,
then the view and image dimensions are taken from the picture file, and
the reported ray origins and directions will exactly match the center of each
pixel in the picture.
.PP
If a depth buffer file is given as well, then
.I vwrays
computes the intersection point of each pixel ray (equal to the ray origin
plus the depth times the ray direction), and reports this instead of the
ray origin.
The reported ray direction will also be reversed.
The interpretation of this data is an image of origins and directions
for light rays leaving the scene surfaces to strike each pixel.
.SH EXAMPLES
To compute the ray intersection points and returned directions corresponding
to a picture and its depth buffer:
.IP "" .2i
vwrays scene_v2.pic scene_v2.zbf > scene_v2.pts
.PP
To determine what the dimensions of a given view would be:
.IP "" .2i
vwrays -d -vf myview.vf -x 2048 -y 2048
.PP
To generate a RADIANCE picture using
.I rtrace
instead of
.I rpict:
.IP "" .2i
vwrays -ff -vf view1.vf -x 1024 -y 1024 |
rtrace `vwrays -d -vf view1.vf -x 1024 -y 1024` -ffc scene.oct > view1.pic
.SH AUTHOR
Greg Ward Larson
.SH ACKNOWLEDGMENT
This work was supported by Silicon Graphics, Inc.
.SH BUGS
Although
.I vwrays
can reproduce any pixel ordering (i.e., any image orientation) when given
a rendered picture, it will only produce standard scanline-ordered rays when 
given a set of view parameters.
.SH "SEE ALSO"
rcalc(1), rpict(1), rtrace(1)
Revision:	1.1
Committed:	Tue Mar 11 19:20:21 2003 UTC (21 years, 2 months ago) by greg
Branch:	MAIN
CVS Tags:	rad3R5
Log Message:	Added documentation to repository
#	User	Rev	Content
1	greg	1.1	.\" RCSid "$Id"
2			.TH VWRAYS 1 1/15/99 RADIANCE
3			.SH NAME
4			vwrays - compute rays for a given picture or view
5			.SH SYNOPSIS
6			.B vwrays
7			.B "[ -i -f{a\|f\|d} \| -d ]"
8			{
9			.B "view opts .."
10			\|
11			.B picture
12			.B [zbuf]
13			}
14			.SH DESCRIPTION
15			.I Vwrays
16			takes a picture or view specification and computes the ray origin and
17			direction corresponding to each pixel in the image.
18			This information may then be passed to
19			.I rtrace(1)
20			to perform other calculations.
21			If a given pixel has no corresponding ray (because it is outside the
22			legal view boundaries), then six zero values are sent instead.
23			.PP
24			The
25			.I -i
26			option may be used to specify desired pixel positions on the standard
27			input rather than generating all the pixels for a given view.
28			.PP
29			The
30			.I -f
31			option may be used to set the record format to something other than the
32			default ASCII.
33			Using raw float or double records for example can reduce the time
34			requirements of transferring and interpreting information in
35			.I rtrace.
36			.PP
37			View options may be any combination of standard view parameters described
38			in the
39			.I rpict(1)
40			manual page, including input from a view file with the
41			.I \-vf
42			option.
43			Additionally, the target X and Y dimensions may be specified with
44			.I -x
45			and
46			.I -y
47			options, and the pixel aspect ratio may be given with
48			.I -p.
49			The default dimensions are 512x512, with a pixel aspect ratio of 1.0.
50			Just as in
51			.I rpict,
52			the X or the Y dimension will be reduced if necessary
53			to best match the specified pixel
54			aspect ratio, unless this ratio is set to zero.
55			.PP
56			If the
57			.I -d
58			option is given, then
59			.I vwrays
60			just prints the computed image dimensions, which are based on the view
61			aspect and the pixel aspect ratio just described.
62			The
63			.I -ld
64			switch will also be printed, with
65			.I -ld+
66			if the view file has an aft clipping plane, and
67			.I -ld-
68			otherwise.
69			This is useful for passing options to the
70			.I rtrace
71			command line.
72			(See below.)
73			.PP
74			If the view contains an aft clipping plane
75			.I (-va
76			option), then the magnitudes of the ray directions will
77			equal the maximum distance for each pixel, which will be interpreted
78			correctly by
79			.I rtrace
80			with the
81			.I -ld+
82			option.
83			Note that this option should not be given unless there is an aft
84			clipping plane, since the ray direction vectors will be normalized
85			otherwise, which would produce a uniform clipping distance of 1.
86			.PP
87			If a picture is given on the command line rather than a set of view options,
88			then the view and image dimensions are taken from the picture file, and
89			the reported ray origins and directions will exactly match the center of each
90			pixel in the picture.
91			.PP
92			If a depth buffer file is given as well, then
93			.I vwrays
94			computes the intersection point of each pixel ray (equal to the ray origin
95			plus the depth times the ray direction), and reports this instead of the
96			ray origin.
97			The reported ray direction will also be reversed.
98			The interpretation of this data is an image of origins and directions
99			for light rays leaving the scene surfaces to strike each pixel.
100			.SH EXAMPLES
101			To compute the ray intersection points and returned directions corresponding
102			to a picture and its depth buffer:
103			.IP "" .2i
104			vwrays scene_v2.pic scene_v2.zbf > scene_v2.pts
105			.PP
106			To determine what the dimensions of a given view would be:
107			.IP "" .2i
108			vwrays -d -vf myview.vf -x 2048 -y 2048
109			.PP
110			To generate a RADIANCE picture using
111			.I rtrace
112			instead of
113			.I rpict:
114			.IP "" .2i
115			vwrays -ff -vf view1.vf -x 1024 -y 1024 \|
116			rtrace `vwrays -d -vf view1.vf -x 1024 -y 1024` -ffc scene.oct > view1.pic
117			.SH AUTHOR
118			Greg Ward Larson
119			.SH ACKNOWLEDGMENT
120			This work was supported by Silicon Graphics, Inc.
121			.SH BUGS
122			Although
123			.I vwrays
124			can reproduce any pixel ordering (i.e., any image orientation) when given
125			a rendered picture, it will only produce standard scanline-ordered rays when
126			given a set of view parameters.
127			.SH "SEE ALSO"
128			rcalc(1), rpict(1), rtrace(1)