International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XL-5/W2, 2013
XXIV International CIPA Symposium, 2 — 6 September 2013, Strasbourg, France
ARCHAEOLOGICAL RESCUE EXCAVATION AND DIGITALIZATION OF CULTURAL
HERITAGE
S. Varea?, J.-B. Lemerle®
"Actual Foncier Topographie, Rouen, France - aft.varea@orange.fr
°AFT Archaeology, Rouen, France — jb.lemerle@aftopo.com
KEY WORDS: Archaeology, digitalization, cultural heritage, terrestrial laser scanning, conservation, 3D, Versailles, Pompei
ABSTRACT:
We present in this paper the original work and projects of AFT, a French company working in the complementary fields of
topography, archaeological rescue excavation and digitalization of cultural heritage. Here are described more precisely the
application of 3D scanning in archaeology, especially in rescue excavation, and the wish of the company to be ahead of its time in
this field., followed by two examples, one in heritage object studies, the other in heritage building studies.
1- RESCUE EXCAVATION
AFT is at the origin an expert land surveyor and topographer, its
office is situated in the urban area of Rouen (Haute-
Normandie). For about six years AFT has diversified its
activities. Indeed, in addition of the classic activities of land
surveyor and topographical surveys, AFT added in a first time
photogrammetric and 3D digitalization activities which
allowed it to work on patrimonial sites on a first time. On a
second time, since summer 2012, AFT has created a new
section of preventive archaeology approved by the French
Ministry of Culture. There are now 3 departments: the
main department for land survey and topography, another for
3D digitalization and. heritage studies, and the last one for
rescue excavations.
The department “AFT Archaeology” was approved by the
French Ministry of Culture on the 22th of June 2012 after the
achievement of a full technical report. This ^ department
counts 15 qualified archaeologists. This team is
working throughout the French territory on Roman and
Medieval archaeological sites.
Through the latest generation technological means, the will of
the society is to be used in the field of Archaeology, challenging
the traditional techniques used by professionals.
2 - DIGITALIZATION TECHNIQUES
3D scanning is a representation of space, according to our
binocular vision and depth perception. The digital acquisition in
three dimensions of an object allows, with current technologies,
rendering scales, measures and identical meshes to the original
object textures, following the three coordinates X, Y and Z. It
consists of a recording spatial data acquired and restored
digitally.
The lasergrammetry enable the position of points in a
coordinate system. To enter and calculate these points into an X,
Y and Z system, it is essential to obtain measures of distances
and angular values.
669
The most common technique for portable scanners is the
triangulation survey: following the distance between the scanner
and a surface, the scanner uses a sensor to define the situation of
a point. The laser spot sensor allows positioning with precision
the coordinates of this point, and indeed creating the form of the
digitized object.
Today's portable scanners offer a frequency up to 20000
measurements per second; these information are recorded by
computer as coordinates of points in three dimensional space.
The set of points products by 3D Scanners must thereafter be
connected order to obtain a continuous surface, a "virtual
object», containing or non colorimetric information.
AFT owns two scanners, representing two types of 3D laser
scanning equipment: The LaserScan Focus 3D 120, by FARO,
and the the handyscan ViewScan, by Creaform.
The LaserScan Focus 3D 120 by FARO, on tripod, is used for
large surface laser surveys (statues, monuments, façades,
archaeological sites, etc.) This appliance has a 120 meters
scope; it allows to capture up 976 000 points per second with a
precision of 0,1 millimeter.
Figure 1. Archaeologists during digitalization
