16 research outputs found
Single-crossing orthogonal axial lines in orthogonal rectangles
The axial map of a town is one of the key components of the space syntax method – a tool
for analysing urban layout. It is derived by placing the longest and fewest lines, called axial
lines, to cross the adjacencies between convex polygons in a convex map of a town. Previous
research has shown that placing axial lines to cross the adjacencies between a collection of
convex polygons is NP-complete, even when the convex polygons are restricted to rectangles
and the axial lines to have orthogonal orientation.
In this document, we show that placing orthogonal axial lines in orthogonal rectangles
where the adjacencies between the rectangles are restricted to be crossed only once (ALPSC-
OLOR) is NP-complete. As a result, we infer the single adjacency crossing version
of the general axial line placement problem is NP-complete. The transformation of NPcompleteness
of ALP-SC-OLOR is from vertex cover for biconnected planar graphs. A
heuristic is then presented that gives a reasonable approximate solution to ALP-SC-OLOR
based on a greedy method
A greedy heuristic for axial line placement in collections of convex polygons
Master of Science - ScienceAxial line placement is one step in a method known as space syntax which is used in town
planning to analyse architectural structures. This is becoming increasingly important in the
quickly growing urban world of today. The field of axial line placement is an area of space
syntax that has previously been done manually which is becoming increasingly impractical.
Research is underway to automate the process and this research forms a large part of the automation.
The general problem of axial line placement has been shown to be NP-complete. For this reason, previous research in this field has been focused on finding special cases where this is not the case or finding heuristics that approximate a solution.
The majority of the research conducted has been on the simpler case of axial line placement in configurations of orthogonal rectangles and the only work done with convex polygons has been in the restricted case of deformed urban grids. This document presents research that finds two non-trivial special cases of convex polygons that have polynomial solutions and finds the first heuristic for general configurations of convex polygons
The structure and function of diagrams in environmental design : a computational inquiry
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 1989.Vita.Includes bibliographical references (leaves 252-261).by Stephen McTee Ervin.Ph.D
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