man/man1/vwrays.1

.\" RCSid "$Id: vwrays.1,v 1.6 2008/11/10 19:08:17 greg Exp $"
.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 \-pa.
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.
The
.I \-pj
option may be used to jitter samples.
The default value of 0 turns off ray jittering.
.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 match the center of each
pixel in the picture (plus optional jitter).
.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.hdr 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.hdr
.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), rtcontrib(1), rtrace(1)
Revision:	1.7
Committed:	Tue Aug 16 02:22:50 2011 UTC (14 years, 2 months ago) by greg
Branch:	MAIN
Changes since 1.6:	+3 -3 lines
Log Message:	Minor fix
#	User	Rev	Content
1	greg	1.7	.\" RCSid "$Id: vwrays.1,v 1.6 2008/11/10 19:08:17 greg Exp $"
2	greg	1.1	.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	greg	1.4	.I \-i
26	greg	1.1	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	greg	1.4	.I \-f
31	greg	1.1	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	greg	1.4	.I \-x
45	greg	1.1	and
46	greg	1.4	.I \-y
47	greg	1.1	options, and the pixel aspect ratio may be given with
48	greg	1.4	.I \-pa.
49	greg	1.1	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	greg	1.4	The
56			.I \-pj
57			option may be used to jitter samples.
58			The default value of 0 turns off ray jittering.
59	greg	1.1	.PP
60			If the
61	greg	1.4	.I \-d
62	greg	1.1	option is given, then
63			.I vwrays
64			just prints the computed image dimensions, which are based on the view
65			aspect and the pixel aspect ratio just described.
66			The
67	greg	1.4	.I \-ld
68	greg	1.1	switch will also be printed, with
69	greg	1.4	.I \-ld+
70	greg	1.1	if the view file has an aft clipping plane, and
71	greg	1.4	.I \-ld-
72	greg	1.1	otherwise.
73			This is useful for passing options to the
74			.I rtrace
75			command line.
76			(See below.)
77			.PP
78			If the view contains an aft clipping plane
79			.I (-va
80			option), then the magnitudes of the ray directions will
81			equal the maximum distance for each pixel, which will be interpreted
82			correctly by
83			.I rtrace
84			with the
85	greg	1.4	.I \-ld+
86	greg	1.1	option.
87			Note that this option should not be given unless there is an aft
88			clipping plane, since the ray direction vectors will be normalized
89			otherwise, which would produce a uniform clipping distance of 1.
90			.PP
91			If a picture is given on the command line rather than a set of view options,
92			then the view and image dimensions are taken from the picture file, and
93	greg	1.7	the reported ray origins and directions will match the center of each
94			pixel in the picture (plus optional jitter).
95	greg	1.1	.PP
96			If a depth buffer file is given as well, then
97			.I vwrays
98			computes the intersection point of each pixel ray (equal to the ray origin
99			plus the depth times the ray direction), and reports this instead of the
100			ray origin.
101			The reported ray direction will also be reversed.
102			The interpretation of this data is an image of origins and directions
103			for light rays leaving the scene surfaces to strike each pixel.
104			.SH EXAMPLES
105			To compute the ray intersection points and returned directions corresponding
106			to a picture and its depth buffer:
107			.IP "" .2i
108	greg	1.6	vwrays scene_v2.hdr scene_v2.zbf > scene_v2.pts
109	greg	1.1	.PP
110			To determine what the dimensions of a given view would be:
111			.IP "" .2i
112	greg	1.5	vwrays \-d \-vf myview.vf \-x 2048 \-y 2048
113	greg	1.1	.PP
114			To generate a RADIANCE picture using
115			.I rtrace
116			instead of
117			.I rpict:
118			.IP "" .2i
119	greg	1.5	vwrays \-ff \-vf view1.vf \-x 1024 \-y 1024 \|
120	greg	1.6	rtrace `vwrays \-d \-vf view1.vf \-x 1024 \-y 1024` \-ffc scene.oct > view1.hdr
121	greg	1.1	.SH AUTHOR
122			Greg Ward Larson
123			.SH ACKNOWLEDGMENT
124			This work was supported by Silicon Graphics, Inc.
125			.SH BUGS
126			Although
127			.I vwrays
128			can reproduce any pixel ordering (i.e., any image orientation) when given
129			a rendered picture, it will only produce standard scanline-ordered rays when
130			given a set of view parameters.
131			.SH "SEE ALSO"
132	greg	1.3	rcalc(1), rpict(1), rtcontrib(1), rtrace(1)