man/man1/vwrays.1

.\" RCSid "$Id: vwrays.1,v 1.7 2011/08/16 02:22:50 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} | -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
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:	1.8
Committed:	Sat Aug 20 20:57:51 2011 UTC (13 years, 8 months ago) by greg
Branch:	MAIN
CVS Tags:	rad4R1
Changes since 1.7:	+5 -2 lines
Log Message:	Added -u option to vwrays for unbuffered output with -i
#	Content
1	.\" RCSid "$Id: vwrays.1,v 1.7 2011/08/16 02:22:50 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} \| -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	View options may be any combination of standard view parameters described
41	in the
42	.I rpict(1)
43	manual page, including input from a view file with the
44	.I \-vf
45	option.
46	Additionally, the target X and Y dimensions may be specified with
47	.I \-x
48	and
49	.I \-y
50	options, and the pixel aspect ratio may be given with
51	.I \-pa.
52	The default dimensions are 512x512, with a pixel aspect ratio of 1.0.
53	Just as in
54	.I rpict,
55	the X or the Y dimension will be reduced if necessary
56	to best match the specified pixel
57	aspect ratio, unless this ratio is set to zero.
58	The
59	.I \-pj
60	option may be used to jitter samples.
61	The default value of 0 turns off ray jittering.
62	.PP
63	If the
64	.I \-d
65	option is given, then
66	.I vwrays
67	just prints the computed image dimensions, which are based on the view
68	aspect and the pixel aspect ratio just described.
69	The
70	.I \-ld
71	switch will also be printed, with
72	.I \-ld+
73	if the view file has an aft clipping plane, and
74	.I \-ld-
75	otherwise.
76	This is useful for passing options to the
77	.I rtrace
78	command line.
79	(See below.)
80	.PP
81	If the view contains an aft clipping plane
82	.I (-va
83	option), then the magnitudes of the ray directions will
84	equal the maximum distance for each pixel, which will be interpreted
85	correctly by
86	.I rtrace
87	with the
88	.I \-ld+
89	option.
90	Note that this option should not be given unless there is an aft
91	clipping plane, since the ray direction vectors will be normalized
92	otherwise, which would produce a uniform clipping distance of 1.
93	.PP
94	If a picture is given on the command line rather than a set of view options,
95	then the view and image dimensions are taken from the picture file, and
96	the reported ray origins and directions will match the center of each
97	pixel in the picture (plus optional jitter).
98	.PP
99	If a depth buffer file is given as well, then
100	.I vwrays
101	computes the intersection point of each pixel ray (equal to the ray origin
102	plus the depth times the ray direction), and reports this instead of the
103	ray origin.
104	The reported ray direction will also be reversed.
105	The interpretation of this data is an image of origins and directions
106	for light rays leaving the scene surfaces to strike each pixel.
107	.SH EXAMPLES
108	To compute the ray intersection points and returned directions corresponding
109	to a picture and its depth buffer:
110	.IP "" .2i
111	vwrays scene_v2.hdr scene_v2.zbf > scene_v2.pts
112	.PP
113	To determine what the dimensions of a given view would be:
114	.IP "" .2i
115	vwrays \-d \-vf myview.vf \-x 2048 \-y 2048
116	.PP
117	To generate a RADIANCE picture using
118	.I rtrace
119	instead of
120	.I rpict:
121	.IP "" .2i
122	vwrays \-ff \-vf view1.vf \-x 1024 \-y 1024 \|
123	rtrace `vwrays \-d \-vf view1.vf \-x 1024 \-y 1024` \-ffc scene.oct > view1.hdr
124	.SH AUTHOR
125	Greg Ward Larson
126	.SH ACKNOWLEDGMENT
127	This work was supported by Silicon Graphics, Inc.
128	.SH BUGS
129	Although
130	.I vwrays
131	can reproduce any pixel ordering (i.e., any image orientation) when given
132	a rendered picture, it will only produce standard scanline-ordered rays when
133	given a set of view parameters.
134	.SH "SEE ALSO"
135	rcalc(1), rpict(1), rtcontrib(1), rtrace(1)