ray/lib/page1.txt



                        The RADIANCE
                  Synthetic Imaging System


                         Greg Ward
                Lawrence Berkeley Laboratory
                      1 Cyclotron Rd.
                    Berkeley, CA  94720
                       (415) 486-4757


1.  Introduction

     RADIANCE was developed as a research tool for  predict-
ing  the  distribution  of  visible radiation in illuminated
spaces.  It takes as  input  a  three-dimensional  geometric
model  of  the  physical  environment, and produces a map of
spectral radiance values as a color image.  The technique of
ray-tracing  follows light backwards from the image plane to
the source(s).  Because it can produce realistic images from
a  simple description, RADIANCE has a wide range of applica-
tions in  graphics  arts,  lighting  design,  computer-aided
engineering and architecture.

     The diagram in Figure 1 shows the flow between programs
(boxes)  and  data  (ovals).   The central program is rpict,
which produces a picture from a scene description.  Rview is
a  variation  of  rpict  that  computes  and displays images
interactively.

     A scene description file lists the surfaces and materi-
als  that  make up a specific environment.  The current sur-
face types are  spheres,  polygons,  cones,  and  cylinders.
They  can be made from materials such as plastic, metal, and
glass.  Light sources can be distant disks as well as  local
spheres and polygons.

     From a three-dimensional scene description and a speci-
fied  view,  rpict produces a two-dimensional image.  A pic-
ture file is a compressed binary representation of the  pix-
els  in  the  image.  This picture can be scaled in size and
brightness, anti-aliased, and sent to a graphics output dev-
ice.

     A header in each picture file lists the program(s)  and
parameters that produced it.  This is useful for identifying
a picture without having to display it.  The information can


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10			The RADIANCE
11			Synthetic Imaging System
12
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14			Greg Ward
15			Lawrence Berkeley Laboratory
16			1 Cyclotron Rd.
17			Berkeley, CA 94720
18			(415) 486-4757
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24
25			1. Introduction
26
27			RADIANCE was developed as a research tool for predict-
28			ing the distribution of visible radiation in illuminated
29			spaces. It takes as input a three-dimensional geometric
30			model of the physical environment, and produces a map of
31			spectral radiance values as a color image. The technique of
32			ray-tracing follows light backwards from the image plane to
33			the source(s). Because it can produce realistic images from
34			a simple description, RADIANCE has a wide range of applica-
35			tions in graphics arts, lighting design, computer-aided
36			engineering and architecture.
37
38			The diagram in Figure 1 shows the flow between programs
39			(boxes) and data (ovals). The central program is rpict,
40			which produces a picture from a scene description. Rview is
41			a variation of rpict that computes and displays images
42			interactively.
43
44			A scene description file lists the surfaces and materi-
45			als that make up a specific environment. The current sur-
46			face types are spheres, polygons, cones, and cylinders.
47			They can be made from materials such as plastic, metal, and
48			glass. Light sources can be distant disks as well as local
49			spheres and polygons.
50
51			From a three-dimensional scene description and a speci-
52			fied view, rpict produces a two-dimensional image. A pic-
53			ture file is a compressed binary representation of the pix-
54			els in the image. This picture can be scaled in size and
55			brightness, anti-aliased, and sent to a graphics output dev-
56			ice.
57
58			A header in each picture file lists the program(s) and
59			parameters that produced it. This is useful for identifying
60			a picture without having to display it. The information can
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