per corner the 
he author. 
  
  
1 has the same 
tive. 
Balletti, Caterina 
  
  
  
  
figure7. de' Barbari's view transformed in a correct central projection. 
1.1.2 Portolans 
The second application, still in progress, is 
on the ancient sea charts, which drawing 
was not built on mathematical principles, 
but on the position of represented points, 
surveyed by reciprocal bearings and 
distances. 
In these maps were absolute the concept of 
bearing based on wind roses. 
Even if portolans were thought as maps 
without a projection, the lack of clear and 
visible coordinates doesn't mean lack of a 
projective system. If some medieval charts 
don't obey any coherent geometrical (or 
cartographic) reticulate, portolans can be 
classified as "orthogonal" maps. 
In a new research (C. Boutoura, Scoperta 
di un il reticolato geografico in una carta 
nautica dell'Egeo del XVI secolo, 
catalogue of the exhibition Raggi di Vento 
sul Mare, Tessaloniki, January 2000 ) the 
connection between the wind roses system 
and the geographic reticulate in sea charts 
is came out. 
The experimentation carried out looks at a series of sea charts, dated in the period before and after the publication of the 
famous Mercator projection, compared and geo-referred respect to a today sea chart in Mercator projection. 
The analytical study of maps deformations provides a methodology based on, in a first step, a global transformation that 
allows a correct bearing of the old map and, in a second time, the application of local transformations (finite elements) 
for a better comparison - correspondence with the reference cartography. 
  
figure8. Sea chart of Sideri of the XVI century. The elaboration underlines the 
wind roses system 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part BS. Amsterdam 2000. 35