ARCHAEOLOGICALILLUSTRATION 179
These are simply ways of converting the information
contained in single-plane views derived from the site
recording into composite three-sided dimensional views.
An isometric drawing (using a 60 degree and 30 degree
set square) is correct along any axis whereas an axono-
metric (greater than 30 or 60 degrees) representation is
correct along one or more.
The representations are usually viewed from a ‘common
corner’, a point at union with the three viewed sides of
the object. All the principal lines of the projection are
parallel to each other within the same plane. The dis-
appearing effect of perspective is not drawn, and there is no
foreshortening needed. All isometric projections of timber
structures (e.g. for details of joints) should always be
checked against the originals if they survive. For standing
structures, front, side and back elevations are desirable
at a scale of 1:10 to provide the necessary information.
Plans (for quays, river wharves, etc.) should be at super-
structural, base-plate and foundation levels, and sections
across such structures should show the relationship of the
timbers to adjacent deposits.Computer-aided design (CAD): Computer draughting
has the ability to produce and manipulate two-dimensionalFigure 18.15 A boatbuilder’s tar brush from western
Scotland. This artefact is made of different organic materials,
and these are indicated by various drawing techniques.
The remains of the handle, seen protruding at the bottom,
are of wood, and this is depicted by lines suggestive of
grain. The band above is of leather, indicated by restrained
stipple and black cracks. Above that are fragments of cord
and fabric, which are given a simple realistic treatment.
The hair of the brush has been worked up with a series
of fine black lines, clustering in areas of shadow. Fine
separation of the ‘hairs’ has been achieved by careful
scraping with a scalpel. (Colin Martin)
Figure 18.16 A render of the 3-D laser-scan data of the
figurehead from HMS Colossus(1798). The high accuracy
of the 3-D laser-scanner is suitable for detailed record-
ing of maritime artefacts and this can be seen on the
recording of subtle tool-marks on the flat knee section.
(Copyright Archaeoptics Ltd; reproduced courtesy of the
Mary Rose Trust)