Engineering: Reports
http://hdl.handle.net/10092/611
2016-06-27T20:02:20ZA study of line reduction methods for interactive computer mapping
http://hdl.handle.net/10092/12379
A study of line reduction methods for interactive computer mapping
Peter, Smith
With the increasing availability of powerful graphics workstations,
interactive computer mapping systems are becoming more and more
popular.
The art of map making is thousands of years old and much is still relevant,
However, with the new electronic media and interactive usage come new
problems.
One important problem is this context is associated with map
generalization. Generalization involves the removal of irrelevant or
excessive data and bas· the goal of achieving the greatest possible clarity of
meaning, good legibilty and simplicity [ref IMH82].
In the past, map generalization has been manual, relying mainly on the
knowledge, experience, and intuition of the individual cartographer. In the
interactive environment generalization must be automated - features
appearing and disappearing as dictated by scale.
As generalization lacks a clear underpinning theory there is still much work
to be done in this field.
This report is mainly (because of time limitations), but not whoJly, to do
with one aspect of generalization - line reduction. Several line reduction
methods are intoduced, and a study is made of their relative effectiveness.
1987-01-01T00:00:00ZScientist's workbook
http://hdl.handle.net/10092/12378
Scientist's workbook
JasonSmith, Michael
This project discusses the scientist's workbook, a system designed to assist scientists'
in their work. An overview of similar systems, such as the Memex
and Xanadu, is presented. The results of a series of interviews with nine scientists
are discussed. In the interviews the scientists expressed difficulty managing
'bookmarks, user defined links into the World Wide Web. This lead to
the design and implementation of a system (SWB) to assist scientist with web
revisitation. A number of design goals for systems that implement web-page
revisitation are given, and the implementation of SWB is detailed.
1999-01-01T00:00:00ZFast evaluation of radial basis functions : methods for four-dimensional polyharmonic splines
http://hdl.handle.net/10092/12377
Fast evaluation of radial basis functions : methods for four-dimensional polyharmonic splines
Cherrie, J. B.; Beatson, R. K.; Ragozin, D. L.
As is now well known for some basic functions ϕ, hierarchical and fast multipole like
methods can greatly reduce the storage and operation counts for fitting and evaluating radial
basis functions. In particular for spline functions of the form
[FORM]
p a low degree polynomial and certain choices of ⏀, the cost of a single extra evaluation can
be reduced from O(N) to O(log N), or even O(1), operations and the cost of a matrix-vector
product (i.e., evaluation at all centres) can be decreased from O(N²) to O(N log N), or even
O(N), operations.
This paper develops the mathematics required by methods of these types for polyharmonic
splines in R⁴. That is for splines s built from a basic function from the list ⏀(r) = r⁻² or
⏀(r) = r²n ln(r), n = 0, 1, .... We give appropriate far and near field expansions, together
with corresponding error estimates, uniqueness theorems, and translation formulae.
A significant new feature of the current work is the use of arguments based on the action
of the group of non-zero quaternions, realised as 2 x 2 complex matrices
[MATRICES]
acting on C² = R⁴. Use of this perspective allows us to give a relatively efficient development
of the relevant spherical harmonics and their properties.
2000-01-01T00:00:00ZGraphical tool for SC automata
http://hdl.handle.net/10092/12348
Graphical tool for SC automata
Haslett, L.
SC automata are a variation of timed automata which are closed under complementation.
The major difference is SC automata have both history clocks
which represent the time since some event occurred in the past and prophecy
clocks which represent the time until some event occurs in the future. Humans
have difficulty understanding and visualising the meaning of prophecy clocks
and constraints which test their values.
A graphical tool for constructing SC automata and experimenting with their
accepting runs is presented. The tools emphasis is to provide understanding
and visualising prophecy clocks rather than being a solid verifier. A simple
evaluation of the tool is also presented.
2000-01-01T00:00:00Z