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imaging problems (forward from sasnet)
Bonnie Blackwell, (BONN@NICKEL.LAURENTIAN.CA)
Fri, 10 Jun 1994 08:08:17 -0500
If anyone has any advice to offer about equipment suitable for
recording 3-dimensionaL coordinates on a complex shape like a
cranium, I would be very grateful if they could contact me at
srgimus@grv.grace.cri.nz or Fax (64-4)387-7419.
For some years a colleague and I have been carrying out research
on cranial shape transformation in the Pacific region using
coordinates from 132 landmarks. The way the coordinates are
recorded is both tedious and labour intensive, requiring intense
concentration to maintain accuracy to better than 1 mm edged
cube. For anyone interested, two publications on this work are
listed below.
The method described in these articles is very primitive, but
reasonably effective. I have also used a Cat scanner with 2mm
slices at 2mm intervals. Although this is satisfactory for facial
tissue reconstruction projects, it is well below the data density
necessary for detailed three-dimensional analysis, particularly
when linked to traditional anatomical landmarks. Higher density
data can be produced, but the X-ray tube heats up to an alarming
degree, and anyway the whole operation is very expensive.
I have seen advertising material relating to an electro-optical
3D digitiser made by Pixsys in Boulder Colorado, which looks as
if it might be quite suitable for this work. If anyone knows of a
person who has used this equipment, I would like to contact them
to ask some pointed questions which one cannot put to a Salesman
and expect a reliable answer. This device is fairly expensive,
about NZ$35,000.
We have tried to use a Reflex microscope, but there are distinct
problems with this for this purpose. The device is excellent for
obtaining accurate coordinates on a surface which can be viewed
from one side of a cube; however, it is very difficult to capture
data from surfaces hidden from the first viewing direction. This
requires reclamping the item, re-establishing the coordinates of
fixed points and starting over again, and then later putting all
the data together. Not very convenient, and the device is much
more expensive than the electro-optical 3D digitiser made by
Pixsys.
Anyone who has any bright ideas about this would they please
contact me.
Foss Leach
Curator, Archaeozoology Laboratory
Museum of New Zealand
PO Box 467, Wellington, NZ
srgimus@grv.grace.cri.nz
Phone (64-4) 387-8254
Fax (64-4) 387-7419
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Buranarugsa, M. and Leach, B.F. 1986. The three-dimensional
analysis of the Polynesian skull. Man and Culture in Oceania 2:
81-100.
Buranarugsa, M. and Leach, B.F. 1993. Coordinate geometry of
Moriori crania and comparisons with M]ori. Man and Culture in
Oceania 9:1-43.
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