man/man1/vwrays.1

.\" RCSid "$Id: vwrays.1,v 1.10 2012/06/14 22:42:21 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
option 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 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), rcode_depth(1), rcontrib(1), rpict(1), rtpict(1), rtrace(1)
Revision:	1.11
Committed:	Thu Nov 7 23:20:28 2019 UTC (5 years, 5 months ago) by greg
Branch:	MAIN
CVS Tags:	rad5R3
Changes since 1.10:	+2 -2 lines
Log Message:	Added ability for pinterp, pmblur2, and vwrays to read 16-bit encoded depth
#	Content
1	.\" RCSid "$Id: vwrays.1,v 1.10 2012/06/14 22:42:21 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	option should be used to jitter sample postions in most cases.
51	.PP
52	View options may be any combination of standard view parameters described
53	in the
54	.I rpict(1)
55	manual page, including input from a view file with the
56	.I \-vf
57	option.
58	Additionally, the target X and Y dimensions may be specified with
59	.I \-x
60	and
61	.I \-y
62	options, and the pixel aspect ratio may be given with
63	.I \-pa.
64	The default dimensions are 512x512, with a pixel aspect ratio of 1.0.
65	Just as in
66	.I rpict,
67	the X or the Y dimension will be reduced if necessary
68	to best match the specified pixel
69	aspect ratio, unless this ratio is set to zero.
70	The
71	.I \-pj
72	option may be used to jitter samples.
73	The default value of 0 turns off ray jittering.
74	.PP
75	If the
76	.I \-d
77	option is given, then
78	.I vwrays
79	just prints the computed image dimensions, which are based on the view
80	aspect and the pixel aspect ratio just described.
81	The
82	.I \-ld
83	switch will also be printed, with
84	.I \-ld+
85	if the view file has an aft clipping plane, and
86	.I \-ld-
87	otherwise.
88	This is useful for passing options to the
89	.I rtrace
90	command line.
91	(See below.)
92	.PP
93	If the view contains an aft clipping plane
94	.I (-va
95	option), then the magnitudes of the ray directions will
96	equal the maximum distance for each pixel, which will be interpreted
97	correctly by
98	.I rtrace
99	with the
100	.I \-ld+
101	option.
102	Note that this option should not be given unless there is an aft
103	clipping plane, since the ray direction vectors will be normalized
104	otherwise, which would produce a uniform clipping distance of 1.
105	.PP
106	If a picture is given on the command line rather than a set of view options,
107	then the view and image dimensions are taken from the picture file, and
108	the reported ray origins and directions will match the center of each
109	pixel in the picture (plus optional jitter).
110	.PP
111	If a depth buffer file is given as well, then
112	.I vwrays
113	computes the intersection point of each pixel ray (equal to the ray origin
114	plus the depth times the ray direction), and reports this instead of the
115	ray origin.
116	The reported ray direction will also be reversed.
117	The interpretation of this data is an image of origins and directions
118	for light rays leaving the scene surfaces to strike each pixel.
119	.SH EXAMPLES
120	To compute the ray intersection points and returned directions corresponding
121	to a picture and its depth buffer:
122	.IP "" .2i
123	vwrays scene_v2.hdr scene_v2.zbf > scene_v2.pts
124	.PP
125	To determine what the dimensions of a given view would be:
126	.IP "" .2i
127	vwrays \-d \-vf myview.vf \-x 2048 \-y 2048
128	.PP
129	To generate a RADIANCE picture using
130	.I rtrace
131	instead of
132	.I rpict:
133	.IP "" .2i
134	vwrays \-ff \-vf view1.vf \-x 1024 \-y 1024 \|
135	rtrace `vwrays \-d \-vf view1.vf \-x 1024 \-y 1024` \-ffc scene.oct > view1.hdr
136	.SH AUTHOR
137	Greg Ward Larson
138	.SH ACKNOWLEDGMENT
139	This work was supported by Silicon Graphics, Inc.
140	.SH BUGS
141	Although
142	.I vwrays
143	can reproduce any pixel ordering (i.e., any image orientation) when given
144	a rendered picture, it will only produce standard scanline-ordered rays when
145	given a set of view parameters.
146	.SH "SEE ALSO"
147	rcalc(1), rcode_depth(1), rcontrib(1), rpict(1), rtpict(1), rtrace(1)