Geography Reference
In-Depth Information
to an alteration in the analogue support; other errors can be recorded in the cartographic
document, for instance errors that were made by the cartographer during survey or draft
steps, or errors inherent to the surveying instruments at that time. In order to compare an
ancient cartographic document to a modern one (usually a modern map used as reference),
a georeferencing process is performed in a digital environment, assigning cartographic
coordinates to a number of still existing and recognizable Ground Control Points (GCPs).
This way, the native metric content of the map can be reproduced in the digital image, and
furthermore an analysis of the existing map deformations is allowed. Thus, it becomes
possible to understand the characteristics of metric precision of the original product (e.g. the
projection type) in respect to the present reference cartographic base, as well as to evaluate
and represent the degree of deformation recorded in the ancient document. The historical
map, now in digital form, can be easily exploited and compared with other cartographic
databases, thanks also to current web services; change analysis and analytical procedures
can be performed through GIS applications.
This way, regeneration of ancient maps in digital form appears to be useful for many users:
not only the public and institutions who collect them, but also experts who exploit this kind
of documents to derive information for their studies, ranging from urban development to
geomorphological or environmental topics. Many institutions today are digitalizing their
cartographic heritage, in order to preserve and catalogue it and give online access to it
(Adcock et al., 2004). On the evidence of growing interest in the argument, the International
Cartographic Association (ICA) instituted in 2007 the “Commission on Digital Technologies
in Cartographic Heritage”, whose aim is to encourage digital approaches to cartographic
heritage.
The present research would demonstrate the usefulness of the digital regeneration of ancient
cartography; it provides an example of studies that can be performed after digital
regeneration of ancient cartography, with a non-conventional approach mainly focused on
technical considerations about the map-making procedures.
2. Materials
In this study, a set of three maps, depicting the northern coast of the Adriatic Sea along the
Po river delta (South of Venice, Italy) at the end of the 16
th
century, is analysed (Figure 1).
The first two maps were both drafted in the year 1592, whereas the third one was drafted
few years later (1599).
The maps represent a rare case where the authors of documents are known. The same
cartographer, Ottavio Fabri, was author of the first map (hereinafter “F map”) and co-author
in the other two (hereinafter “P map” and “L map”), in which the main authors were
Gerolamo Pontara and Bonaiuto Lorini, respectively. All of them were very famous land-
surveyors in Renaissance Venice (
Savi ed Esecutori delle Acque della Serenissima Repubblica
).
The dimensions of these documents are very large, and their average scales range between
about 1:12,000 and 1:13,000, not being constant throughout the entire maps. The original
