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Hierarchical representations of 3-dimensional objects are both time and space efficient. They typically consist of trees whose branches represent bounding volumes and whose terminal nodes represent primitive object elements (usually polygons). This paper describes a method whereby the object space is represented entirely by a hierarchical data structure(More)
We describe a set of utility routines for 3-D shaded display which allow us to create raster scan display systems for various experimental and production applications. The principal feature of this system is a flexible scan conversion processor that can simultaneously manage several different object types. Communications between the scan conversion routine(More)
We illustrate two enhancements to procedural geometric models which allow autonomous procedures to jointly satisfy mutual constraints. One of the techniques adds communications paths between procedures which may affect one another. Conflicts are resolved by modifying communicating procedures as they execute.The second technique is a generalization of widely(More)
This paper presents three scan line methods for drawing pictures of parametrically defined surfaces. A scan line algorithm is characterized by the order in which it generates the picture elements of the image. These are generated left to right, top to bottom in much the same way as a picture is scanned out on a TV screen. Parametrically defined surfaces are(More)
This paper describes an implementation of Cook's "shade trees" in which shaders are described as networks of modules, building blocks, whose connections can be defined interactively.The high level interface to the shaders is a graphical editor which permits users to construct complex shaders by connecting shading elements in a network, in effect a graphical(More)
One of the main goals in realistic rendering is to generate images that are indistinguishable from photographs – but how do observers decide whether an image is photographic or computer-generated? If this perceptual process were understood, then rendering algorithms could be developed to directly target these cues. In this paper we introduce an experimental(More)