man/man1/vwrays.1

.\" RCSid "$Id: vwrays.1,v 1.5 2007/09/04 17:36:41 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 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.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:	1.6
Committed:	Mon Nov 10 19:08:17 2008 UTC (16 years, 5 months ago) by greg
Branch:	MAIN
CVS Tags:	rad4R0
Changes since 1.5:	+3 -3 lines
Log Message:	Changed ".pic" extension to ".hdr" throughout
#	Content
1	.\" RCSid "$Id: vwrays.1,v 1.5 2007/09/04 17:36:41 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 -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 \-pa.
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	The
56	.I \-pj
57	option may be used to jitter samples.
58	The default value of 0 turns off ray jittering.
59	.PP
60	If the
61	.I \-d
62	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	.I \-ld
68	switch will also be printed, with
69	.I \-ld+
70	if the view file has an aft clipping plane, and
71	.I \-ld-
72	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	.I \-ld+
86	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	the reported ray origins and directions will exactly match the center of each
94	pixel in the picture.
95	.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	vwrays scene_v2.hdr scene_v2.zbf > scene_v2.pts
109	.PP
110	To determine what the dimensions of a given view would be:
111	.IP "" .2i
112	vwrays \-d \-vf myview.vf \-x 2048 \-y 2048
113	.PP
114	To generate a RADIANCE picture using
115	.I rtrace
116	instead of
117	.I rpict:
118	.IP "" .2i
119	vwrays \-ff \-vf view1.vf \-x 1024 \-y 1024 \|
120	rtrace `vwrays \-d \-vf view1.vf \-x 1024 \-y 1024` \-ffc scene.oct > view1.hdr
121	.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	rcalc(1), rpict(1), rtcontrib(1), rtrace(1)