man/man1/rtpict.1

.\" RCSid "$Id: rtpict.1,v 1.5 2019/12/19 04:56:44 greg Exp $"
.TH RTPICT 1 3/19/2018 RADIANCE
.SH NAME
rtpict - generate a RADIANCE picture or layerd image using rtrace
.SH SYNOPSIS
.B rtpict
.B "-n nproc"
[
.B "-o[vrxlLRXnNsmM] out_dir"
][
.B "-d ref_depth/unit"
]
[
.B "rpict options"
]
[
.B @file
]
.B octree
.SH DESCRIPTION
.I Rtpict
is a script that generates a picture from the RADIANCE scene given in
.I octree
and sends it to the standard output, or to a file specified with the
.I \-o
option.
Most options and defaults are the same as
.I rpict(1),
although a few switches are silently ignored.
Options incompatible with multi-processing can generate an error.
.PP
The
.I rtrace(1)
tool is called with
.I vwrays(1)
to perform the actual work.
This enables the
.I \-n
option for multiprocessing on platforms that support it.
If the
.I \-n
option is not specified or is set to 1, then
.I rpict
is called directly.
There is no benefit in setting the number of processes to anything
greater than the number of virtual cores available on your machine.
Also, it is very important to set the
.I \-af
option if an irradiance cache is being generated;
otherwise, your speed-up will be far from linear.
.PP
If the
.I \-o
option has additional characters corresponding to output types from
.I rtrace,
it must be followed by the name of a directory that either exists or
will be created to contain image layers, one per output type.
The supported types are listed below, and do not include types that
are useless or have no convenient representation.
The table below shows the correspondence between output type and file name
in the specified directory:
.sp
.nf
v       radiance.hdr
r       r_refl.hdr
x       r_unrefl.hdr
l       d_effective.dpt
L       d_firstsurf.dpt
R       d_refl.dpt
X       d_unrefl.dpt
n       perturbed.nrm
N       unperturbed.nrm
s       surface.idx
m       modifier.idx
M       material.idx
.fi
.sp
Different encodings are associated with different data types.
Color data (from the 'v', 'r', and 'x' types) will be converted to
a flat RGBE picture by
.I pvalue(1).
Distances (from the 'l', 'L', 'R', and 'X' types) will be
converted to a 16-bit representation by
.I rcode_depth(1),
and the
.I \-d
option should be used to assign the reference (median) depth and world
units, which applies to the overall scene.
Surface normals (from the 'n' and 'N' types) will be converted
to a 32-bit representation by
.I rcode_normal(1).
Finally, identifiers (from the 's', 'm', and 'M' types) will be
converted to a 16-bit index format by
.I rcode_ident(1).
.PP
If the
.I \-i
option is used to turn on irradiane output, then the picture associated
with the 'v' type will be renamed
.I "irradiance.hdr"
and some other output types become irrelevant (i.e., 'r', 'x', 'R', and 'X').
If one or more of the associated output files already exists in the
destination directory, it will be overwritten with the new data.
.SH EXAMPLES
To render a scene with four processes:
.IP "" .2i
rtpict -n 4 -vf mypers.vf -ab 1 -af scene.amb scene.oct > scene_pers.hdr
.PP
To render radiance, first surface distance, and normals in a layered image:
.IP "" .2i
rtpict -n 8 -vf fish.vf @render.opt -ovLn fisholay scene.oct
.SH NOTES
Users should seriously consider using
.I rpiece(1)
when irradiance caching is employed with a shared ambient file.
If
.I rtpict
is used in multiprocessing mode with a shared irradiance cache,
it is trying to compute almost
the same part of the same scanline in different processes, which
results in many redundant calculations.
The
.I rpiece
program avoids this by working on separate tiles in each
process, with less overlap in the indirect irradiance calculation.
Either program will benefit from an "overture" run of a
single-process rpict to create the ambient file using a low-resolution
rendering that is discarded, but this will not completely solve the
problem for
.I rtpict.
.SH AUTHOR
Greg Ward
.SH "SEE ALSO"
getinfo(1), mkpmap(1), oconv(1), pfilt(1), 
pvalue(1), rad(1), rcode_depth(1), rcode_normal(1), rcode_ident(1),
rpiece(1), rpict(1), rsplit(1), rtrace(1), rvu(1), vwrays(1),
Revision:	1.6
Committed:	Wed May 6 14:23:18 2020 UTC (4 years, 11 months ago) by greg
Branch:	MAIN
Changes since 1.5:	+20 -1 lines
Log Message:	Added note about shared ambient values
#	User	Rev	Content
1	greg	1.6	.\" RCSid "$Id: rtpict.1,v 1.5 2019/12/19 04:56:44 greg Exp $"
2	greg	1.1	.TH RTPICT 1 3/19/2018 RADIANCE
3			.SH NAME
4	greg	1.3	rtpict - generate a RADIANCE picture or layerd image using rtrace
5	greg	1.1	.SH SYNOPSIS
6			.B rtpict
7	greg	1.2	.B "-n nproc"
8	greg	1.1	[
9	greg	1.3	.B "-o[vrxlLRXnNsmM] out_dir"
10			][
11			.B "-d ref_depth/unit"
12			]
13			[
14	greg	1.1	.B "rpict options"
15			]
16			[
17			.B @file
18			]
19			.B octree
20			.SH DESCRIPTION
21			.I Rtpict
22			is a script that generates a picture from the RADIANCE scene given in
23			.I octree
24			and sends it to the standard output, or to a file specified with the
25			.I \-o
26			option.
27			Most options and defaults are the same as
28			.I rpict(1),
29			although a few switches are silently ignored.
30			Options incompatible with multi-processing can generate an error.
31			.PP
32			The
33			.I rtrace(1)
34			tool is called with
35			.I vwrays(1)
36			to perform the actual work.
37			This enables the
38			.I \-n
39			option for multiprocessing on platforms that support it.
40			If the
41			.I \-n
42			option is not specified or is set to 1, then
43			.I rpict
44			is called directly.
45			There is no benefit in setting the number of processes to anything
46			greater than the number of virtual cores available on your machine.
47			Also, it is very important to set the
48			.I \-af
49			option if an irradiance cache is being generated;
50			otherwise, your speed-up will be far from linear.
51	greg	1.3	.PP
52			If the
53			.I \-o
54			option has additional characters corresponding to output types from
55			.I rtrace,
56			it must be followed by the name of a directory that either exists or
57			will be created to contain image layers, one per output type.
58			The supported types are listed below, and do not include types that
59			are useless or have no convenient representation.
60			The table below shows the correspondence between output type and file name
61			in the specified directory:
62			.sp
63			.nf
64			v radiance.hdr
65	greg	1.4	r r_refl.hdr
66			x r_unrefl.hdr
67			l d_effective.dpt
68			L d_firstsurf.dpt
69			R d_refl.dpt
70			X d_unrefl.dpt
71	greg	1.3	n perturbed.nrm
72			N unperturbed.nrm
73			s surface.idx
74			m modifier.idx
75			M material.idx
76			.fi
77			.sp
78			Different encodings are associated with different data types.
79			Color data (from the 'v', 'r', and 'x' types) will be converted to
80			a flat RGBE picture by
81			.I pvalue(1).
82			Distances (from the 'l', 'L', 'R', and 'X' types) will be
83			converted to a 16-bit representation by
84			.I rcode_depth(1),
85			and the
86			.I \-d
87	greg	1.5	option should be used to assign the reference (median) depth and world
88			units, which applies to the overall scene.
89	greg	1.3	Surface normals (from the 'n' and 'N' types) will be converted
90			to a 32-bit representation by
91			.I rcode_normal(1).
92			Finally, identifiers (from the 's', 'm', and 'M' types) will be
93			converted to a 16-bit index format by
94			.I rcode_ident(1).
95			.PP
96			If the
97			.I \-i
98			option is used to turn on irradiane output, then the picture associated
99			with the 'v' type will be renamed
100			.I "irradiance.hdr"
101			and some other output types become irrelevant (i.e., 'r', 'x', 'R', and 'X').
102			If one or more of the associated output files already exists in the
103			destination directory, it will be overwritten with the new data.
104			.SH EXAMPLES
105	greg	1.1	To render a scene with four processes:
106			.IP "" .2i
107			rtpict -n 4 -vf mypers.vf -ab 1 -af scene.amb scene.oct > scene_pers.hdr
108	greg	1.3	.PP
109			To render radiance, first surface distance, and normals in a layered image:
110			.IP "" .2i
111			rtpict -n 8 -vf fish.vf @render.opt -ovLn fisholay scene.oct
112	greg	1.6	.SH NOTES
113			Users should seriously consider using
114			.I rpiece(1)
115			when irradiance caching is employed with a shared ambient file.
116			If
117			.I rtpict
118			is used in multiprocessing mode with a shared irradiance cache,
119			it is trying to compute almost
120			the same part of the same scanline in different processes, which
121			results in many redundant calculations.
122			The
123			.I rpiece
124			program avoids this by working on separate tiles in each
125			process, with less overlap in the indirect irradiance calculation.
126			Either program will benefit from an "overture" run of a
127			single-process rpict to create the ambient file using a low-resolution
128			rendering that is discarded, but this will not completely solve the
129			problem for
130			.I rtpict.
131	greg	1.1	.SH AUTHOR
132			Greg Ward
133			.SH "SEE ALSO"
134	greg	1.3	getinfo(1), mkpmap(1), oconv(1), pfilt(1),
135			pvalue(1), rad(1), rcode_depth(1), rcode_normal(1), rcode_ident(1),
136			rpiece(1), rpict(1), rsplit(1), rtrace(1), rvu(1), vwrays(1),