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Item Rendering NURB Regions For 2D Animation(Blackwell Science Ltd and the Eurographics Association, 1992) Willis, Philip; Oddy, RobertWe describe an accurate method of rendering by scan-conversion of closed regions bounded by NURBs, with particular comments on its application to computer-based 2D animation. It is shown that the method is fast, analytically accurate, and can be readily extended to include anti-aliasing and clipping.Item Scan Converting Extruded Lines at Ultra High Definition(Blackwell Publishing Ltd and the Eurographics Association, 1987) Willis, Philip; Watters, GeoffWe consider the problem of generating freehand raster graphics pictures at ultra high definition (typically one gigapixel per picture) by scan converting extruded lines. We describe a fast scan conversion algorithm which is linear in final resolution and which incorporates a number of features to ensure high efficiency. Sample pictures and corresponding performance figures are included.Item UltraPaint: A New Approach to a Painting System(Blackwell Publishing Ltd and the Eurographics Association, 1987) Watters, Geoff; Willis, PhilipThe ideas underlying a Painting System being developed at the University of Bath are introduced. This differs from a conventional system in that ultra high definition pictures of upto 1 gigabyte may be created. We discuss approaches to implementing a number of standard paint program utilities in a form suited to our high definition method. Finally, we describe an algorithm for the rapid extrusion of brush strokes on a raster device.Item Graphical Interaction Management(Blackwell Publishing Ltd and the Eurographics Association, 1987) Barn, Balbir S.; Willis, PhilipGraphical interfaces and interactive graphical programmes are awkward to write because of a lack of top-down structure. A methodology for constructing graphical programs will be described, together with a system that generates the basic interaction requirements for such applications.Item Browsing High Definition Colour Pictures(Blackwell Publishing Ltd and the Eurographics Association, 1985) Willis, Philip; Milford, DavidThe authors describe a method of presenting colour pictures which allows users to browse by panning and zooming. The pictures are seen as though on a 512 by 512 by 12 bit framestore, but are defined to 4096 by 4096. The implementation allows the entire picture to be seen in overview, with fine details averaged, or to be zoomed in upon with finer detail progressively revealed by a sequence of twofold linear magnifications. Further zooming, beyond the resolution of the picture data, automatically produces a conventional pixel replication effect. In addition, the picture may be panned vertically or horizontally.Item Classification of Quad-encoding Techniques(Blackwell Science Ltd and the Eurographics Association, 1991) Hunter, Andrew; Willis, PhilipMany quad encoding technique have been published previously, using a variety of approaches to the different facets of quad storage, representation and manipulation. We review the major classes and identify three parameters which distinguish them. These are then used explicitly to classify a large number of published methods, with short discussion on each. In doing this we are also able to highlight some new approaches, to identify rare examples which escape the classification, and to suggest approaches to choosing a method to suit a given application.Item A Picture Archive Browser(Blackwell Science Ltd and the Eurographics Association, 1991) Willis, Philip; Hunter, AndrewWe describe an implementation of a networked picture browser. The system offers a pictorial interface to pictorial data, relieves the users of thinking about the underlying filing system, provides managerial tools for installing, moving and deleting pictures, offers graded access and picture sharing and supports a number of picture formats, including hierarchical encodings.