Decision-making algorithms in geometric modelling
Many of the applications of geometric modelling are
concerned with the computation of well-defined
properties of the model. The applications which have
received less attention are those which address
questions to which there is no unique answer. This
thesis describes such an application: the automatic
production of a dimensioned engineering drawing. Dna
distinctive feature of this operation is the requirement
for sophisticated decision-making algorithms at each
stage in the processing of the geometric model. Hence,
the thesis is focussed upon the design j development and
implementation of such algorithms.
Various techniques for geometric n~odell:i.ng are briefly
examined and then details are given of the modelling
package that was developed for this project, The
principles of orthographic projection and dimensionj.n.g
are treated and some published work on the theory of
dimensioning is examined. A new theoretical approach to
dimensioning is presented and discussed.
The existing body of knowledge on decision-making is
sampled and the~author then shows how methods which were
originally developed for management decisions may be
adapted to serve the purposes of this project.
The remainder of the thesis is devoted to reports on the
development of decision-making algorithms for
orthographic view selection, sectioning and crosshatching,
the preparation of orthographic views with
essential hidden detail, and two approaches to the
actual insertion of dimension lines and text.
The thesis concludes that the theories of decisionmaking
can be applied to work of this kind. It may be
possible to generate computer solutions that are closer
to the optimum than some man-made dimensioning schemes.
Further work on important details is required before a
commercially acceptable package could be produced.