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The RADIANCE |
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Synthetic Imaging System |
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Greg Ward |
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Lawrence Berkeley Laboratory |
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1 Cyclotron Rd. |
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Berkeley, CA 94720 |
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(415) 486-4757 |
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1. Introduction |
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RADIANCE was developed as a research tool for predict- |
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ing the distribution of visible radiation in illuminated |
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spaces. It takes as input a three-dimensional geometric |
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model of the physical environment, and produces a map of |
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spectral radiance values as a color image. The technique of |
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ray-tracing follows light backwards from the image plane to |
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the source(s). Because it can produce realistic images from |
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a simple description, RADIANCE has a wide range of applica- |
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tions in graphics arts, lighting design, computer-aided |
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engineering and architecture. |
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The diagram in Figure 1 shows the flow between programs |
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(boxes) and data (ovals). The central program is rpict, |
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which produces a picture from a scene description. Rview is |
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a variation of rpict that computes and displays images |
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interactively. |
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A scene description file lists the surfaces and materi- |
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als that make up a specific environment. The current sur- |
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face types are spheres, polygons, cones, and cylinders. |
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They can be made from materials such as plastic, metal, and |
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glass. Light sources can be distant disks as well as local |
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spheres and polygons. |
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From a three-dimensional scene description and a speci- |
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fied view, rpict produces a two-dimensional image. A pic- |
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ture file is a compressed binary representation of the pix- |
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els in the image. This picture can be scaled in size and |
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brightness, anti-aliased, and sent to a graphics output dev- |
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ice. |
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A header in each picture file lists the program(s) and |
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parameters that produced it. This is useful for identifying |
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a picture without having to display it. The information can |
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