Acquiring the data for the Portolan chart analysis

We acquired the data of the analysis of the Dulcert 1339 Portolan Map in the following way:

Locations were identified on an image of the map (this is the neighbourhood of Genoa)

Those locations were marked in Google Earth:

Here a detail

From those markers the coordinates are copied. For the copy process Google Earth gives the coordinates in an XML format on the PC’s clipboard:

<?xml version=”1.0″ encoding=”UTF-8″?>
<kml xmlns=”http://www.opengis.net/kml/2.2&#8243; xmlns:gx=”http://www.google.com/kml/ext/2.2&#8243; xmlns:kml=”http://www.opengis.net/kml/2.2&#8243; xmlns:atom=”http://www.w3.org/2005/Atom”&gt;
<Folder>
<name>Portolaan</name>
<open>1</open>
<Placemark>
<name>Ventimiglia</name>
<Point>
<coordinates>7.601403,43.790505,0</coordinates>
</Point>
</Placemark>
<Placemark>
<name>San Remo</name>
<Point>
<coordinates>7.776990999999999,43.814689,0</coordinates>
</Point>
</Placemark>
<Placemark>
<name>Taggia (Fora di Taggia rm)</name>
<Point>
<coordinates>7.859868,43.831383,0</coordinates>
</Point>
</Placemark>
<Placemark>
<name>Capo Mele</name>
<Point>
<coordinates>8.173166,43.955039,0</coordinates>
</Point>
</Placemark>
<Placemark>
<name>Albenga (Fiume Centa rm)</name>
<Point>
<coordinates>8.221926,44.041946,0</coordinates>
</Point>
</Placemark>
<Placemark>

Those coordinates are pasted into the Portolan program, where each plotted location gets a moveable dot, that can be dragged to the position where it is drawn on the map. Previously plotted places provide an approximate projection that puts the places already in the right neighbourhood based on their true geographical coordinates.

This gives us the positions in pixels relative to the lower left corner of the image (columns X and Y).

The whole image has a size of 9112 x 6477 pixels.

and 1015 individual places, shown as green dots above, were identified and plotted bij Jeff van Hout in this project that was initiated on his Mediaeval History discussion site of Nifterlaca

http://www.nifterlaca.nl/read.php?3,17477,17699#msg-17699

And here are those 1015 places on Google Earth

 

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