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fig8 de' Barbari's view transformed in a correct central projection. In the upper corner the superimposition of the scheme of the original 
view and of the correct one to underline the deformations introduced by the author 
What are the conclusions that can be obtained from this 
first phase of geometric analysis? 
The view is certainly not a correct perspective, but it does 
present some quite clear deformations. Such 
deformations can be blamed on accidental errors or 
“desired” errors. In the first case, it involves errors in the 
perspective construction or in the plan, in the second case 
to a quite precise intention by the author. 
The analysis done would lead to affirm that Jacopo 
de’Barbari did not make mistakes in the geometric 
construction of the perspective involuntarily (when the 
map was published, the rules of perspective were by then 
consolidated, and it is impossible to believe that de’ 
Barbari, considering the cultural circles in which he lived 
and worked, had been incapable of applying them), but 
indeed, he voluntarily introduced these deformations for 
apparent political and symbolic reasons ( in fact, he 
dilated the area of San Marco, the symbol of the 
institutional power of the city, while the map contracts 
those parts of the peripherical urban texture not yet well 
defined). It involves, therefore, some “political” errors to 
which however, the errors in the planimetry can be 
summed: from the geometric analysis of the planimetry, it 
would seem evident that he did not have a rigorous 
planimetry of the city available for use. 
New technologies for historic cartography 
The transformations dealt with in the first part of this text, 
allow for the deformation of a chart in such a way as to 
make them assume the metric and geometric contents of 
another reference chart. This leads to the manipulation of 
the chart in question, which is subject to the deformation 
which are at times, so great as to completely distort the 
original aspect. The price to be paid for rendering a 
historic chart metrical according to the current parameters 
can be the loss of the semantic content of the map itself. 
This situation, while acceptable for didactic reasons or for 
research purposes, is not acceptable for those who wish 
to read a map in its original state. 
Is it therefore correct to distort the aspect of a map to the 
point of rendering it unrecognisable in order to assign it a 
new metric necessary? Can one avoid the geometric 
transformation of a chart and find alternate ways to 
facilitate its quantitative reading? How can we combine 
the desire to extract geometric information from a historic 
map while still maintaining the original aspect? 
In order to positively answer these questions we must 
introduce a radical change in the way to benefit from 
cartography which must change from a paper chart to a 
digital chart. 
The techniques of warping can be utilised, not for 
transforming the charts but in order to create 
correspondences, realising specific software which 
manage and visualise these correspondences between 
the charts. The procedure of referencing-transformation 
remains valid but is supported by and even replaced in 
some cases with the procedure of referencing- 
correspondence. 
The analytic and algorithmic part of the two procedures is 
the same: 
global transformations + local transformations (warping) 
These change the ways to apply the transformations and 
change the support of the cartographic image which in the 
correspondence becomes numeric and not graphic. 
Computer and “info-graphics” come to be of use: the 
solution is that of using software able to place in bi 
univocal correspondence and visualise, interactively and 
in real time, a current numeric reference chart and a 
digital image of the historic chart. This is possible by 
using the analytic part of the plane transformations, used 
not for creating a new image, but rather, to calculate the 
positions of the homologous points on the two charts. 
The 2W software, designed and implemented for this • 
research project, responds to these characteristics. 
The software provides to windows, side by side, in which 
the photoplane of Venice (1982) is visualised in one 
window and the de’Barbari's one is visualised in the other.