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Title
New perspectives to save cultural heritage
Author
Altan, M. Orhan

SCANNING OPTIONS AND CHOICES IN DIGITIZING HISTORIC MAPS
M. Daniil * 1,2 ’ a , V. Tsioukas l 2,b , K. Papadopoulos 2,c , E. Livieratos 3 ' 2 ' d
1 Demokritos University of Thrace, Dept, of Architecture, Xanthi, Greece.
2 National Centre for Maps and Cartographic Heritage - National Map Library, Thessaloniki, Greece.
3 Aristotle University of Thessaloniki, Dept, of Surveying Engineering, Thessaloniki, Greece.
a miltos@maplibrary.gr; b vtsiouka@arch.duth.gr; c kostas@maplibrary.gr; d livier@topo.auth.gr
WG 4 - Digital Image Processing
KEY WORDS: Scanner, Photography, Cartography, Historical maps, Cartographic Heritage, Digital map archives
ABSTRACT:
The introduction of modem digital imaging techniques in historical cartography, especially in documenting old map collections,
meets the need for extending and complying image processing and relevant photogrammetric tools in the analysis of antique maps in
the context that digital photogrammetry intersects the modem theories in digital treating of old maps.
In this paper we discuss some aspects in controlling the geometric features of the scanned images of antique maps in terms e.g. of
linear, angular and areal deformation. Collateral effects influencing the scanned map image are also talked namely the statistics and
the image quality of the output map images with respect to the original map and/or the “reference” digital best scanned image.
1. INTRODUCTION ■ In some cases are not directly accessible.
m
In the second group the following items can be assembled:
■ The map-scale, usually small and loosely defined.
■ The drawing method, the projective properties and
the associated map deformations, which in most of
the cases are veiled especially in the pre-scientific
cartography.

All the above -and obviously some more to be identified or de
termined- led us to the idea that the use of photogrammetric me
thods and techniques are worth to be extensively tried and
tested in historical map processing, mainly the digital counter
part, which is a new trend in modem cartographic culture
(Livieratos and Myridis, 1999; Livieratos et al., 1999). Old
maps cannot be treated just like any other hardcopy printed on
paper or other relevant supporting material. Most of them are
not well preserved and properly stored. This makes their digital
transformation a not easy job since the conventional approach
is not proper. In the conventional approach applied in modem
map hardcopies, digitalisation is the result of a direct contact of
the original with the scanning device without taking into ac
count the overall technical specifications of the device. This is
not the case for old maps due to the very concrete reasons
mentioned above.
In order to face the digital treatment of old maps considering
the particularities of the issue, the following scheme of actions
could be attempted. The old map can be digitised in two modes:
■ In the traditional direct mode (DM).
■ In the photogrammetry-prone indirect mode (IM)
involving an a-posteriori direct digression.
These two basic modes are in fact the acquisition procedures in
order to store the digital files of old maps (dfs) for the shake of
their documentation and archiving but also for their further ana
lysis and interpretation.
varying.
In the modem era of mapping, photogrammetry was always
interacting with cartography in the field of mapmaking. Since
the first processing of aerial photographs in the framework of
analog photogrammetry in the past century, maps became more
precise depicting in all possible scales parts of the real world
space. Modem technology using computers, digital photogram
metry (Schenk, 1999) and specialized hardware and software in
creased the above mentioned interaction and support the emer-
tion of new domains of science and technology bom from the
intersection of already well founded fields as it is digital photo
grammetry and cartography in all its folds, especially the digital
one. Although historical maps are not of course based on photo
grammetric information and at a first sight seems that there is no
relevance at all between the two disciplines (at least for maps
before the era of photogrammetric mapping), this paper will at
tempt to introduce a new view and understanding in how histo
rical cartography and digital photogrammetry could meet and
produce new products assisting the analysis and the interpreta
tion of many hidden mysteries of old maps at least as far as their
geometric content is concerned.
2. THE BASICS OF THE IDEA
Among the very special and particular characteristics of old
maps one could pick the following, which are taken here in two
groups for the shake of the example. The first concerns the de
gree of alteration of the material and the second the geometric
properties of the content.
In the first group one should stress the fact that, generally spea
king, old maps:
* Are indeed sensitive as material objects.
■ They are often partially damaged in various ways and
degrees.
■ The thickness of the map-sheet in its different kinds is
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