Tag Archives: Maritime Routes

Analysis of the auction values in the Venetian Incanto system over time

Ancient title of the project: Piracy and corsairs in the Mediterranean Sea.

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In the previous blogpost, we agreed on the data we would like to collect for our study, and identified possible avenues to acquire such data. Unfortunately, as it is often the case with real life experiments, we soon realized that our expectations and milestones were overoptimistic, as our preliminary investigation revealed two major issues: not only the available data was incredibly scarce, but also it was most of the time unreliable and not properly cited, and therefore unsuited for a scientific study.

Identification of a new problematic
Given the time constraints and the apparent dead end in which our explorations lead us, we decided to enlarge a bit our range of investigation: instead of limiting ourselves to the initially proposed inquiry, we seeked more generally for interesting, reliable and (most of all) available data about Mediterranean sea and maritime routes.
The huge database provided by the work of Doris Stöckly, that we previously identified as a possibly interesting source of information, appeared to us as a very valuable resource. This database was in particular referencing the Venetian Incanti for many years and various maritime routes. This ingenious system, a security service introduced to protect maritime routes from potential risks such as piratery, appeared to us as a natural and smooth transition towards a new subject of investigation. After a preliminary exploration of the database, we formulated an interesting problematic: how was the risk attenuated and distributed across maritime routes by the Venetian  Incanti? Can we identify trends and regular patterns in the Incanti that the pirates could have exploited by understanding the logic of this security system?

As a testbed for our study, we chose the seven maritimes routes depicted in the book Le système de l’Incanto des galées du marché à Venise: fin XIIIe – milieu XVe siècle of Doris Stöckly [1]. Moreover, the database provided in the cited textbook contains information about the auction prices for each galley travelling for a specific Maritime route. To propose statistical analysis of these prices for different periods of time, the creation of a digital database is needed. The problematic was then to pass these data from the paper format to the digital format.

  1. Creation of the digital database 

The first idea was to use some optical character recognition tools. Indeed, they permit to create an Excel file from a digitized source of information. Different tools were tested but none gave satisfactory results. The utilization of one of these methods might lead to a nonsense because the human-based validation of the data is highly time-consuming. Instead of this option, the crowdsourcing option has been selected, allowing to share the job between different people through the internet. The advantage is that the transcription of one page of data (paper) by a human takes only 10 minutes against one day if only one person would do it alone. The preparation of the crowdsourcing process was done by both authors and includes: the numerization of the paper-based data with a scanner and the preparation of a clear protocol to be sure that the task is comprehensible with a minimal reflexion. It is a basic rule for a successful crowdsourcing in order to be sure that people collaborate. All the coworkers have to transcribe one page of data in Excel. It will allow authors to compile them and create a SQL-based database. For example, a simple database can be created using “Access” (Microsoft Office) and it will allow simple SQL requests to obtain different statistical information about the auctions of the Incanti system.

Data collection process
FIGURE 1 – Data collection process

The database is really simple because it will finally be composed of a single attribute table for each maritime route.

UML diagram of the database.
FIGURE 2 – UML diagram of the database.
  1. The use of GIS tools

One other main step was to create the vectorial layer containing the 7 maritime routes in order to be able to depict, on a map, the auction values of each route at a specific period of time. In other words, the final goal is to connect the database of the auction values (created before) with a geographical space. A GIS software is needed to do that. The one used here is Quantum GIS (QGIS) because its a free, user-friendly and really powerful GIS software.
Thanks to the dhlab (EPFL), we received a CSV (comma separated values) file which contained the localisation of all the ancient mediterranean harbours used during the Incanti era. This file provides the name of each harbour and the coordinates (longitude, latitude) of each of them. By a really simple manipulation, we can create a shapefile (vectorial) picturing all the harbours:  

Harbours in the Mediterranean Sea.
FIGURE 3 – Harbours in the Mediterranean Sea.

To construct the maritime routes, we created CSV files containing each harbours visited by each route (so 7 CSV files where created), based on information provided by the website [2]. These CSV files were downloaded into QGIS and converted into shapefiles. These shapefiles can be used to draw automatically the road, using the QGIS plugin “pointsToPaths”.  You can see the functionalities of this plugin in Figure 4.

FIGURE 4 – Explications about the QGIS plugin “pointsToPahts”

This tool is not perfect because it does not take into account the coastlines. It is then possible that one part of a maritime route passes through the land, which is not desired. To correct these anomalies, a “by-hand” correction was chosen because they are not many. QGIS allows the user to correct, erase or draw features in a vectorial layer. To perform good corrections, it’s necessary to preserve the integrity of the vectorial layer, i.e. maintain proper topology (for more information about the topology in GIS, click here). A lot of tools are available on QGIS for the edition of shapefiles. On Figure 5, the 7 digitized routes with the harbours are depicted. The background map is an “open street map” view of the mediterranean coasts. Furthermore, some additional corrections need to be done.

FIGURE 5 - Map of the Incanti maritime routes.
FIGURE 5 – Map of the Incanti maritime routes.

Next steps – milestones:

  • To finish the crowdsourcing process and to create the SQL database (until 07.04.15)
  • To find a way to superimpose this data on QGIS, according to each routes (until 14.04.15)
  • To find a relevant visual representation (on map) to give an answer to our problematic (until 31.04.15)
  • To prepare the final report and the poster for the presentation (until the 13.05.15)


[1] Le système de l’Incanto des galées du marché à Venise: fin XIIIe – milieu XVe siècle of Doris Stöckly

[2] Web-SIG of the EPFL Digital Humanities Lab, http://incanti.dhlab.ch/