man/man1/vwrays.1

.\" RCSid "$Id: vwrays.1,v 1.12 2021/12/04 16:29:29 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 -u -f{a|f|d} -c rept | -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.
If the
.I \-u
option is also given, output will be unbuffered.
.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
The
.I \-c
option repeats each pixel the given number of times (default is 1).
This is most useful when sending rays to
.I rcontrib(1)
with the same
.I \-c
setting, providing a much faster way to average pixels over image sets.
The
.I \-pj
and/or
.I \-pd
options should be used to jitter sample postions in most cases.
.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
.I \-pd
option specifies a world-diameter aperture for depth-of-field jittering.
The default value of 0 for both options turns off all 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 has an aft clipping plane.
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), rcode_depth(1), rcontrib(1), rpict(1), rtpict(1), rtrace(1)
Revision:	1.13
Committed:	Sat Apr 9 17:18:08 2022 UTC (3 years ago) by greg
Branch:	MAIN
CVS Tags:	rad5R4, HEAD
Changes since 1.12:	+2 -4 lines
Log Message:	fix(vwrays): No longer spits out -ld- with -d option, only -ld+
#	Content
1	.\" RCSid "$Id: vwrays.1,v 1.12 2021/12/04 16:29:29 greg Exp $"
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 -u -f{a\|f\|d} -c rept \| -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	If the
29	.I \-u
30	option is also given, output will be unbuffered.
31	.PP
32	The
33	.I \-f
34	option may be used to set the record format to something other than the
35	default ASCII.
36	Using raw float or double records for example can reduce the time
37	requirements of transferring and interpreting information in
38	.I rtrace.
39	.PP
40	The
41	.I \-c
42	option repeats each pixel the given number of times (default is 1).
43	This is most useful when sending rays to
44	.I rcontrib(1)
45	with the same
46	.I \-c
47	setting, providing a much faster way to average pixels over image sets.
48	The
49	.I \-pj
50	and/or
51	.I \-pd
52	options should be used to jitter sample postions in most cases.
53	.PP
54	View options may be any combination of standard view parameters described
55	in the
56	.I rpict(1)
57	manual page, including input from a view file with the
58	.I \-vf
59	option.
60	Additionally, the target X and Y dimensions may be specified with
61	.I \-x
62	and
63	.I \-y
64	options, and the pixel aspect ratio may be given with
65	.I \-pa.
66	The default dimensions are 512x512, with a pixel aspect ratio of 1.0.
67	Just as in
68	.I rpict,
69	the X or the Y dimension will be reduced if necessary
70	to best match the specified pixel
71	aspect ratio, unless this ratio is set to zero.
72	The
73	.I \-pj
74	option may be used to jitter samples.
75	The
76	.I \-pd
77	option specifies a world-diameter aperture for depth-of-field jittering.
78	The default value of 0 for both options turns off all ray jittering.
79	.PP
80	If the
81	.I \-d
82	option is given, then
83	.I vwrays
84	just prints the computed image dimensions, which are based on the view
85	aspect and the pixel aspect ratio just described.
86	The
87	.I \-ld
88	switch will also be printed, with
89	.I \-ld+
90	if the view has an aft clipping plane.
91	This is useful for passing options to the
92	.I rtrace
93	command line.
94	(See below.)
95	.PP
96	If the view contains an aft clipping plane
97	.I (-va
98	option), then the magnitudes of the ray directions will
99	equal the maximum distance for each pixel, which will be interpreted
100	correctly by
101	.I rtrace
102	with the
103	.I \-ld+
104	option.
105	Note that this option should not be given unless there is an aft
106	clipping plane, since the ray direction vectors will be normalized
107	otherwise, which would produce a uniform clipping distance of 1.
108	.PP
109	If a picture is given on the command line rather than a set of view options,
110	then the view and image dimensions are taken from the picture file, and
111	the reported ray origins and directions will match the center of each
112	pixel in the picture (plus optional jitter).
113	.PP
114	If a depth buffer file is given as well, then
115	.I vwrays
116	computes the intersection point of each pixel ray (equal to the ray origin
117	plus the depth times the ray direction), and reports this instead of the
118	ray origin.
119	The reported ray direction will also be reversed.
120	The interpretation of this data is an image of origins and directions
121	for light rays leaving the scene surfaces to strike each pixel.
122	.SH EXAMPLES
123	To compute the ray intersection points and returned directions corresponding
124	to a picture and its depth buffer:
125	.IP "" .2i
126	vwrays scene_v2.hdr scene_v2.zbf > scene_v2.pts
127	.PP
128	To determine what the dimensions of a given view would be:
129	.IP "" .2i
130	vwrays \-d \-vf myview.vf \-x 2048 \-y 2048
131	.PP
132	To generate a RADIANCE picture using
133	.I rtrace
134	instead of
135	.I rpict:
136	.IP "" .2i
137	vwrays \-ff \-vf view1.vf \-x 1024 \-y 1024 \|
138	rtrace `vwrays \-d \-vf view1.vf \-x 1024 \-y 1024` \-ffc scene.oct > view1.hdr
139	.SH AUTHOR
140	Greg Ward Larson
141	.SH ACKNOWLEDGMENT
142	This work was supported by Silicon Graphics, Inc.
143	.SH BUGS
144	Although
145	.I vwrays
146	can reproduce any pixel ordering (i.e., any image orientation) when given
147	a rendered picture, it will only produce standard scanline-ordered rays when
148	given a set of view parameters.
149	.SH "SEE ALSO"
150	rcalc(1), rcode_depth(1), rcontrib(1), rpict(1), rtpict(1), rtrace(1)