Browsing by Author "McPheeters, Craig"

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    COMPUTER ANIMATION AT THE UNIVERSITY OF CALGARY
    (1984-04-01) Wyvill, Brian; Maulsby, David; McPheeters, Craig
    The computer has been used as a tool to aid animation artists in a number of ways; from controlling rostrum cameras to producing complete animation sequences from three dimensional descriptions of real objects. This paper describes Graphicsland, a suite of programs developed to explore the medium of 3D animation. Graphicsland recognizes that there is no single "correct" approach to solving the problems of design, storage, movement, rendering and production of animated film and video. Instead a variety of techniques are offered and the design of the system is such that it may easily be extended to incorporate new algorithms and graphical databases in the future.
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    PRACTICAL GRAPHICS FOR 3D COMPUTER ANIMATION
    (1985-01-01) Wyvill, Brian; Jansonius, Corine; Novacek, Milan; McPheeters, Craig; Pearce, Andrew
    Presented here are a collection of practical techniques in computer graphics which are reasonably easy to implement and produce an acceptable degree of realism for a small investment in programming time. Most of these techniques are not in themselves particularly complex but refinements on well known algorithms. Taken together they form a collection of ideas which may be of interest to other workers in the field. Research in various aspects of realistic graphics and animation requires a testbed system in which to produce results from experiments with specific areas of interest. For example to test the effectiveness of a volcanic eruption manufactured from particles, it is necessary to have at least rudimentary animation infrastructure available. In this paper we describe some of the ways in which we provide this infrastructure with the limited resources available in a typical university research environment consisting of a VAX 780 running UNIX and a frame buffer. These methods have been developed during the building of a computer animation system called Graphicsland at the University of Calgary.
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    SOFT OBJECTS
    (1985-10-01) Wyvill, Geoff; McPheeters, Craig; Wyvill, Brian
    We introduce the concept of soft objects whose shape changes in response to their surroundings. Established geometric modelling techniques exist to handle most engineering components, including free form shapes such as car bodies and telephones. More recently, there has been a lot of interest in modelling natural phenomenon such as smoke, clouds, mountains and coastlines where the shapes are described stochastically, or as fractals. None of these techniques lends itself to the description of soft objects. This class of objects includes fabrics, cushions, living forms, mud and water. In this paper, we describe a method of modelling such objects and discuss its uses in animation. Our method is to represent a soft object, or collecion of objects, as a surface of constant value in a scalar field over three dimensions. The main technical problem is to avoid calculating the field value at too many points. We do this with a combination of data structures at some cost in internal memory usage.
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    SOLID TEXTURING OF SOFT OBJECTS
    (1987-01-01) Wyvill, Geoff; Wyvill, Brian; Pearce, Andrew; McPheeters, Craig
    Since the shape of a Soft object changes in response to its surroundings, it is difficult to give a single position in space as the location of the object. Indeed objects can and do break into sub-objects dynamically. This means that you cannot map a solid texture onto such an object simply using a function of the space co-ordinates. We have taken a different approach. Our soft objects are modelled as the volume enclosed by an iso-surface of a field calculated from a set of key points. We ascribe to each key point a set of values which represent a position in an abstract texture space. Any point on the surface of an object has a field value due to each key point and this value is used as a weight in finding a weighted vector sum of these positions. This vector sum is used to select a surface specification from the texture space. These textures retain their consistency during distortion and metamorphoses of objects. A great variety of animation effects can be achieved with this process.
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    A TUTORIAL GUIDE TO THE ANI ANIMATION SYSTEM
    (1984-12-01) McPheeters, Craig; Wyvill, Brian
    ANI is a three dimensional animation control program. It was developed in the department of Computer Science at the University of Calgary as part of the graphics land environment. ANI works as an animation environment that easily defines many types of different animation techniques. Although ANI was not designed for the non-experienced computer user, it should not be very hard to master enough of the concepts and commands to start doing basic animation very quickly. ANI works very closely with a system called PG (Polygon Groper), and can only animate objects created in PG. For those of you who would like to advance to sophisticated animation techniques, I highly recommend that you learn the basics of, and become familiar with PG. ANI was not designed to handle real-time animation (being able to see things move in front of you immediately), although some limited facilities exist to do this. Rather ANI was designed to create all of the individual pictures, which would then later be put on film or video tape. I will be mentioning various programs throughout this manual. For the location of these programs in your particular installation, please refer to your Graphics land administrator.