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X/2/2019
INTERDISCIPLINARIA ARCHAEOLOGICA
NATURAL SCIENCES IN ARCHAEOLOGY
homepage: http://www.iansa.eu
Thematic Review
Current Development in Archaeological Remote Sensing:
A Central European Experience and Evaluation
Martin Gojda
a,b*
a
Institute of Archaeology, Praha, Czech Academy of Sciences, Letenská 4, Praha 1, Czech Republic
b
Institute of Archaeology, University of Cardinal Stefan Wyszyński, Wóycickiego 1/3, Warszawa, Poland
1. Introduction
As a consequence of the collapse of communist regimes in
former Warsaw-Pact countries, the early 1990s became a
period in which aerial archaeology in Central-Eastern Europe
began to write its own history. This article ofers the present
author’s refections on the these developments and changes
within the feld of archaeological remote sensing over the
last quarter of a century, along with a personal evaluation
of the current situation of the subject’s methodology with
an eye to the future, based on his practical involvement in
systematic, long-term, aerial archaeological prospection and
past landscape and settlement research.
In the history of
archaeological remote sensing
(ARS),
the last couple of decades have brought several fundamental
improvements to its methodology and datasets. These
are pushing the discipline of Earth’s remote sensing into
the group of archaeology’s most important instruments of
cognitive processes. As a consequence, the crucial role of
ARS in the current research and management of ancient/
historical landscapes, sites and monuments is obvious.
The article describes how current trends are changing the
traditional objective of aerial archaeology – prehistoric and
ancient site detection and photographic recording – into a
much more complex aim, namely: the integration of a variety
of modern digitally-based sophisticated techniques of RS that
are applicable to archaeology into the study of diachronic
developments and synchronic structures of components of
ancient and historical landscapes and settlements. Also included
below are notes on the signifcant role of orthophoto maps
recently accessible to the general public via web portals (such as
globally-based Google Earth, and many national map servers/
geoportals) and how to deal with this challenge in the context
of sites and monuments research and management. The author
presents an assessment of the role of ARS in the study of the
past from a central European (mainly Czech) perspective.
2. Theoretical considerations
2.1 Detecting the unknown and seeing the context. Non-
destructiveness as a modern archaeology postulate
To observe any kind of reality from a distance means to see
it both as a whole and in context with its surroundings. This
Volume X ● Issue 2/2019 ● Pages 155–164
*Corresponding author. E-mail: gojda@arup.cas.cz
ARTICLE INFO
Article history:
Received: 5
th
May 2019
Accepted: 7
th
November 2019
DOI: http://dx.doi.org/ 10.24916/iansa.2019.2.5
Key words:
aerial archaeology
archaeological remote sensing
central Europe
internet map (geo)portals
landscape archaeology
satellite data
UAV
ABSTRACT
This article ofers thoughts on how current trends are changing the traditional objective of aerial
prospection – prehistoric and ancient sites detection and the photographic record – into a more complex
aim, namely, the integration of a variety of modern digitally-based, remote-sensing techniques
applicable to archaeology into a process that focuses on the study of diachronic developments and
synchronic patterns of past settlements. The author presents an evaluation of the current position of
remote sensing in the study of the past, mainly from a central European (Czech) perspective, based on
his long-term involvement in air survey and landscape archaeology in the Czech Republic.
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generally allows us to refect on its complexity. This is true
at least when looking at such an intricate component of the
world like the Earth’s surface. Its infnitely long evolution
has been continually infuenced by natural (geologic,
climatic, biological) processes, and which human impact has
then transformed from what used to be entirely natural into a
cultural landscape. These processes have shaped the surface
of the Earth and continuously transformed its seemingly
stable and unchanging character.
The role of archaeology in contemporary Europe has
shifted from the more traditional stress on investigation
through the excavation of individual sites potentially rich
in artefacts/structures/features towards the identifcation,
documentation, mapping and protection of archaeological
landscapes for both research objectives and public interest.
This orientation corresponds well to the “landscape stream”,
one of the most fascinating phenomena, that has attracted
recent populations, at least on a European scale. Several
works summarising the academic approaches to landscape,
and defning the principles of landscape archaeology,
have been published since the beginning of this century
(
e.g.
, Doneus, 2013, pp.29–38; Fairclough, Møller, eds.,
2008; Gojda, 2007; Darvill, Gojda, eds., 2001). This
archaeological practice has been more common in Western
European countries, but thanks to the increasing number of
pan-European projects operating in EU schemes, and due to a
certain number of large-scale, state-funded, national research
projects in some post-communist countries, it has recently
been spreading over this part of Europe as well. Consequently
it is non-invasive methods of archaeological research which,
since the turn of the 21
st
century, have taken over the main
role in theoretically-motivated (research) projects based
on data collected from sites that are not endangered by
development. This was explicitly proclaimed as a postulate
in the early 1990s when the priority of non-invasive methods
was stressed as a point of archaeological ethics at the
Valetta Convention for the Protection of the Archaeological
Heritage of Europe. Nevertheless, despite the global trends
indicating a dominance of non-invasive prospection and feld
techniques, it is excavation that has maintained its position
as the most frequently-applied archaeological method in the
heart of Europe, primarily as a legally-supported response to
permanent construction activities that have been continuously
threatening archaeological heritage since 1990 on a vast scale.
Concerning non-invasive methods, ARS, from a historical
perspective, is probably the most important. It ranks
among the limited number of techniques that have made
a contribution to the study and understanding of ancient
and historical (medieval, post-medieval, industrial, early
modern) periods of the human past. The importance of ARS
integration into the study of settlement processes has been
compared, for instance, to the invention of the telescope
for the study of outer space. Among the methods for
gathering/processing/interpreting archaeological data, RS
is of high signifcance and is equal to radiocarbon dating,
digital databases, DNA analysis and GIS. At the end of the
1960s and the early 1970s, Leo Deuel, writing about aerial
archaeology in his famous book
Flights into Yesterday
,
claimed that “…no other technical advance in archaeology
has come so close to fulflling the goal of recovering intricate
cultural contexts, of glimpsing whole prehistoric landscapes,
and of capturing a fabric of human existence through the fux
of time” (Deuel, 1973, p.26).
2.2 The 1990s – 2000s turnaround: from aerial
archaeology to archaeological remote sensing
Recent technological development has infuenced several
archaeological branches, and it is clear that ARS has
profted greatly from modern technology: the innovative
instruments, devices and techniques invented and produced
during the last three decades. It was precisely in this period
that the author established aerial archaeology in Bohemia
and pushed for the inclusion of this discipline in Czech
archaeology. Starting from 1992/3, the position was set in
the traditional Crawfordian way of aerial prospection as
developed in the 1920s and as such was recently termed
“observer-based/directed reconnaissance/aerial surveying”
(Verhoeven, Sevara, 2016), “interpretive” (Šmejda, 2017)
and “active-interpretive” (Gojda, 2017). It was based on a
visual survey of the Earth’s surface from a small aircraft
fying at an elevation of c. 300 metres, taking photographs
with three analogue, steady cameras and one video camera,
navigating visually with the aid of a set of 1:50,000 paper
maps, and then, fnally, waiting a week or so to fnd out
how successful the mission was after the set of flms were
developed and images enlarged in a commercial laboratory.
A couple of years later, an innovative process was launched
that gradually changed aerial archaeology (also referred to
as aerial archaeological prospection/reconnaissance/survey)
into archaeological remote sensing – a group of techniques/
methods that produced a variety of remotely-sensed data and
helped to process and analyse them by sophisticated (digital)
procedures:
1. 1993–1995 – the arrival of GNSS/GPS for civilian
use and the declassifcation of the USA’s CORONA
satellite imagery;
2. Second half of the 1990s – digital photography
introduced to the global market; concerning aerial
prospection it greatly simplifed the photography
process both on board the aircraft (only one camera
needed) and after fights (immediate image processing
and large-scale digital applicability);
3. 1999 – the launch of the frst satellite system
(IKONOS) producing images of very high (sub-metre)
spatial resolution (in panchro), extremely important
for the central European region with a prevalence of
small features (pits and small sunken huts at buried,
prehistoric and early medieval, settlements);
4. Around 2005 – free access via Google Earth to
continuous (seamless) global orthophoto coverage (in
the Czech Republic, the frst national map server was
launched at the same time, with currently accessible
imagery taken in fve years between 2003–2017; more
details follow in the next section);
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5. 2005–2010 – the beginning of the massive application
of airborne laser scanning (ALS) in European
archaeology, perhaps the most revolutionary post-
Second
World War impact on the efective (fast,
precise, 3D, digital,….) detection and mapping of our
archaeological landscape heritage (this is absolutely
true for at least central Europe where ancient, medieval
and post-medieval ruined features are preserved as
earthworks almost entirely in woodlands).
6. Late 2000s onward – intensifed application of image
spectrometry using air- and spaceborne, hyperspectral
data and experimentation with automated (computer-
supervised) object (
i.e.
features of archaeological
origin) detection from remotely sensed imagery.
There is no doubt that these innovations fundamentally
changed the traditional image of aerial archaeology, which
before this turnaround was – together with the rare application
of early satellite imagery and aerial infrared photography
(practiced before the 1990s mostly by American scholars,
including in their European projects; Madry, 1987) – the
exclusive method connected with the study of the (pre)historic
landscape from above. The process relegated (traditional)
aerial archaeology to the position of just one of several
methods integrated into the archaeological remote-sensing
“package”. Nevertheless, it is obvious that the integration of
modern (digitally-based) sophisticated techniques of ARS
with additional feld techniques, historical, cartographic
and scientifc methods/data has a chance to produce more
reliable results in the cognitive process focused on the study
of diachronic developments and synchronic structures of the
components of past settlements and landscapes.
2.3 The potential of remote sensing for central
European/Czech archaeology in the 21
st
century
The cognitive process, which in science/research strives to
integrate a discipline’s general level with contemporaneous
technological achievements and theoretical concepts
(paradigms), is never a linear one or one easy to coordinate.
The current position of ARS is somewhat strange in that
this was formerly a purely detection method predominantly
dependent on the observational, physical and interpretative
abilities of trained individuals (commonly termed
aerial archaeologists), while during the last few years
a fundamental change in the ARS agenda (platform)
has occurred – primarily as a consequence of the rapid
technological development. Today, the dependence of
scholars (such as archaeologists, historical geographers,
historical environmentalists/ecologists,
etc.
) on the aerial
reconnaissance specialists’ yearly cropmark “harvest” is
decreasing. The ability to work with sophisticated software
and digital-image data processing, particularly by the
younger generation, makes it possible to incorporate air/
spaceborne data into everyday practice – both in the feld and
during desktop data processing. Vast collections of aerial and
satellite images, both recent and archival, taken continuously
over the Earth in digital format, are available in open-
accessed map portals and geoportals. It is this phenomenon
of free accessibility to worldwide air/spaceborne imagery
that has radically shifted and, in a sense, democratised the
Figure 1.
Orthophotos of the Ctiněves site (north-west Bohemia) from the years 2006 (bottom left), 2012 (top left), 2015 (top right) and 2016 (bottom
right) as recorded on the internet map portal www.mapy.cz. Cropmarks of about 200 pits, two rectangular ditched enclosures and other structures are well
recognisable on the images taken in 2006 and 2016 in the late spring.
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