This thesis deals with computer generated images.
The thesis begins with an overview of a generalised
computer graphics system, including a brief survey of typical
methods for generating photorealistic images. One such
technique, ray tracing, is used as the basis for the work
which follows. The overview section concludes with a
statement of the aim which is to:
Investigate the effective use of available processing
power and effective utilisation of available memory by
implementing a ray tracing programme which uses space
subdivision, multiple processors and a distributed
world model database.
The problem formulation section describes the ray
tracing principle and then introduces the main areas of study.
The INMOS Transputer (a building block for concurrent
systems) is used to implement the multiple process ray tracer.
Space subdivision is achieved by repeated and regular
subdivision of a world cube (which contains the scene to be
ray traced) into named cubes, called octrees. The subdivision
algorithm continues to subdivide space until no octree
contains more than a specified number of objects, or until the
practical limit of space subdivision is reached.
The objects in the world model database are distributed
in a round robin manner to the ray trace processes. During
execution of the ray trace programme, information about each
object is passed between processes by a message mechanism.
The concurrent code for the transputer processes, written
in OCCAM 2, was developed using timing diagrams and signal
flow diagrams derived by analogy from digital electronics.
Structure diagrams, modified to be consistent with OCCAM 2
processes, were derived from the timing diagrams and signal
flow diagrams. These were used as a basis for the coding.
The results show that space subdivision is an effective
use of processor power because the number of trial
intersections of rays with objects is dramatically reduced.
In addition, distribution of the world model database avoids
duplication of the database in the memory of each process and
hence better utilisation of available memory is achieved.
The programmes are supported by a menu driven interface
(running on a PC AT) which enables the user to control the
ray trace processes running on the transputer board housed in
the PC.
| Identifer | oai:union.ndltd.org:ADTP/218850 |
| Date | January 1991 |
| Creators | Cooper, C., n/a |
| Publisher | University of Canberra. Information Sciences & Engineering |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | ), Copyright C. Cooper |
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