Title:
|
Non-contact evaluation of the geometric properties of highway surfacing textures using close range photogrammetry
|
The following thesis is a summary of work undertaken over a five year period
investigating the potential of one method of remote measurement to evaluate
the geometrical properties of highway surface textures. The character and
configuration of surface textures contribute significantly to the safety and
serviceability of highway pavements. A synopsis of current evaluation
methods is considered followed by a detailed consideration of close range
photogrammetry in its application to surface modelling. Close range
photogrammetry is used to construct models based on the Delaunay
triangulation algorithm. The outputs from these models are evaluated initially
against the benchmark standard of the Mean Texture Depth (MTD) derived
from the Volumetric Sand Patch (VSP).
The approach addresses a significant range of surfacings at varying mesh
spacings and in several contexts with results and conclusions presented at
the macro and in some instances the micro scale. Images were collected
within laboratory and field contexts and compared for models of surfaces at
locations in Scotland, areas of mainland Europe and along the eastern
seaboard of the United States of America.
Images were post processed using ImageMaster™ proprietary
photogrammetric software at varying mesh spacings and Triangular Irregular
Networks (TIN) generated for subsequent analysis and manipulation in other
spatial and surface analysis software including ArcGIS ™ and Digital Surf
Mountains Map ™ Premium surface analysis software. The integrity of the
TINs is evaluated against TINs of a group of surfacing materials generated
from photogrammetry and a ZScanner™ 800 handheld 3D laser scanner
with a stated resolution of 50 microns.
The thesis does not simply present photogrammetry as an alternative to
traditional volumetric methods of estimating MTD but also as a convenient
method of generating an array of surface information that may be compared
to functional parameters in recognised British, European and International
Standards.
|