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DigiCULT
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Info
7
GATHERING THE DIGITAL DATA
THROUGH LASER SCANNING
O
ne of the great advantages of
3D laser scanning technology is
that only the laser light makes
contact with the surface, allowing even
very vulnerable surfaces to be scanned
without risk.The lasers used in laser scan-
ning are the same type of low-power red
light laser used in barcode readers and CD
players and are not capable of generating
enough light emission to cause damage.
Factum Arte has rejected the use of point
lasers and works with strip lasers that spre-
ad the light intensity over a strip that
varies in size depending on the scanning
system.Two different laser scanning systems
were used to scan the Dama de Elche: the
ModelMaker W, used to scan the overall
shape and surface of the sculpture; and the
Seti Scanner, used to capture the surface
detail.
The ModelMaker W
The ModelMaker W is manufactured by
3D Scanners UK (http://www.3dscan
ners.co.uk/).The system consists of a scan-
ning head mounted onto a Faro arm atta-
ched to a tripod.The scanning head is
designed to be held in the hand and the
path of the laser strip is controlled manual-
ly. Using the ModelMaker system, the
scanning of the Dama de Elche was car-
ried out in three days.The data was then
merged and meshed, using 300-micron
mesh,
1
by 3D Scanners using Raindrop
Geomagic software.
The Seti Scanner
The Seti Scanner, used to scan the surface
detail, is a system designed by Factum Arte.
The Seti Scanner is a 3D laser scanning
ning head travels along the linear guide.
The position and movement of the scan-
ning head are fully mechanised and con-
trolled by computer. After each horizontal
pass the head is automatically repositioned
to record another pass. It took about four
and a half hours to record the complete
face of the sculpture.The Seti Scanner uses
Riscan software to capture and display the
data but additional software was written by
Factum Arte to remove scanner artefacts,
reposition the scanning head and merge
the data from each pass.This has been an
essential part of the work as it was crucial
that the data was used in its unmeshed
form and that post processing was effecti-
vely eliminated. At no point was the data
optimised in order to facilitate subsequent
processes like 3D printing and routing.The
difference between the data recorded with
the Seti Scanner and that recorded on a
Minolta Vivid 910 is clear if a direct com-
parison is made between output data.
SOURCING AND TESTING OF
MATERIALS
T
he block of limestone from
which the Dama de Elche was
carved has been identified as
being local to the area around the town of
Elche, so fragments that were similarly
weathered and had surface colouring that
resembled the surface of the sculpture were
gathered from quarries in the area.The use
of natural materials significantly adds to
the realism of the finished replica and, by
using stone that is as close as possible to
the original, the replica is faithful not only
in general appearance but also in physical
substance.This also means that the replica
will probably age in a similar way. Back at
the studio the fragments were pulverised
and sieved.Tests were carried out, using
system that consists of a high resolution
Reversa 25 scanning head, made by 3D
Scanners UK, mounted onto specially con-
structed, servo driven xyz linear guides,
controlled by a CNC (Computer
Numerical Controller). It has a maximum
working resolution of 100 microns both
along and between the scanning lines and
a depth of field of 25 mm. Once the scan-
ner has been set up it scans in a series of
horizontal passes.The scanning head emits
a single strip of laser light which passes
across the surface of the object as the scan-
1 300 microns is roughly the size of a pin head.
Z Corp print of the face from the meshed Minolta data.The Z corp print
was made in 100 micron layers but compared to the milled data from the
Seti Scanner the surface lacks detail and has the appearance of a sucked sweet.
Routed face from the unmeshed Seti Scanner data.The routing was carried
out by Delcam UK using a complex routing strategy with a final cut of 100
microns.
Factum
Ar
te
,
2004,
www
.f
actum-ar
te
.com
Factum
Ar
te
,
2004,
www
.f
actum-ar
te
.com