Tag Archives: Cartography

Timemap of the Venetian Empire

The timemap of the Venetian Empire project aims to bridge the gap between maps of the Venetian Empire at a given year, and timelines of the Venetian history. The idea is to associate the historical events linked with a change of the boundaries of the Venetian Empire with a geographical representation of these changes. The final result is a map of the Venetian Empire covering continuously a period of five Centuries, enriched with descriptions giving insight in the historical events leading to the displayed changes.

The chosen framework for data representation is the Timemap Google code project. This javascript frameworks allows us to easily display polygons on Google Earth Tiles, while associating event descriptions to these polygons. A typical example of the resulting representation is shown below.

Basic timeline example

A basic example of Timemap

As a starting point, I chose to use the Euratlas dataset that was provided to me. These Shapefiles represent political maps of Europe every 100 years. I selected the year 1100 as a starting point, and extracted the coordinates of the vertices constituting the polygons part of the Venetian Empire at that time. These coordinates are cartesian and still have to be converted in geodetic format (latitude and longitude) to be displayed by Google Earth. This conversion is done using Matlab’s mapping toolbox.

The next step of the project was to gather the most important events in the history of Venice leading to a change of the boundaries of the Empire. At first, I focused on the Domini da Mar, namely the venetians maritime possessions, which began with the Venetian Crusade(1122-1124), and gained a lot of importance following the Fourth Crusade (1202-1204), as can ben seen in timemap below. This maritime part is based on Mélanie Fournier’s previous work on the Venetian colonies. Later on, I focused on the Domini di Terraferma, which represent the continental expansion of the Venetian Empire. In particular, the reconquest of the Dalmatia region, lost by the Venetians in 1358, was treated in detail. For each event, I gathered and compared data from several sources, which are detailed in the source code of the timemap.

Once the set of relevant events was selected, I defined the changes of boundaries associated to each event. Defining the boundaries of the newly conquered or acquired territories is an easy task in the case of islands, but proves to be more difficult for continental territories, as obvious natural boundaries are not always present.

In particular, determining precisely the precise boundaries of the dominions to the north of Venice would have required an extensive research. The shape of the Empire changed many times and rather rapidly over the course of thirty years. Furthermore, several cities, like Crema and Cremona, went back and forth between a Venetian control and the rule of the Milanese. The Euratlas data, corresponding to the outermost of boundaries of these states, is only provided at the beginning of each Century and was of no use. In this region, I used this map as an approximation of the boundaries of interest. One should, however, consider it carefully as it has been proved to be wrong in the Dalmatia region, and some dates indicated do not match those of other sources. I nevertheless decided to include these divisions for visualisation purposes, as it allowed me to link an event (the conquest of a city) to a part of the Venetian Empire. As previously, the sources of the descriptions and dates chosen to represent the historical events are indicated in the source code of the timemap. The dates indicated in the timemap correspond to the final time at which Venetians secured the territory. Most of these continental Dominions, as well as Dalmatia, remained under control of the Serenissima until the surrender of the city to Napoleon, in 1797.

Once the changes of boundaries associated to the selected events are determined, they have to be formated as polygons in order to be displayed by the Google Maps API. For this purpose, I used the Polygon creator tool. This tool allows the user to recover the coordinates of a set of manually marked points on the map forming a polygon. These points are then formatted in the Google Maps Polygon format, and inserted in the Javascript routine generating the map. The figure below presents the process of generating a polygon covering the island of Naxos. The final timemap consists of over 3000 points defining polygons.

Creation of a polygon covering the island of Naxos

Creation of a polygon covering the island of Naxos

As the amount of events starts growing, it was necessary to tweak the chosen timemap framework in order to introduce a more intuitive utilization and a clearer display of the events associated to the map. To this end, the size of the map and the proportions allocated to its three components were modified. The increments of the time slider were fine tuned, and the text boxes displaying the events description reworked. Finally, we also added two buttons to control the zoom level on the map.

The timemap is divided in three parts. The top part represents the events, on which the user can click to center the map. The middle part is used for navigating in time, and the bottom part is the map representing the state of the Venetian Empire in any given year. Clicking in any of the highlighted zones or on the event names brings up a small window with some detail on the relevant event. The different colors on the map represent the period of acquisition of the territories (one color per Century).

Timemap of the Venetian Empire

Zoom: [+] []

A possible further improvement would be to make use of the hot zones feature of the Timemap framework. This function allows one to dynamically change the speed of time browsing as a function of the date. This would allow for a more informative visualization of chains of events happening in the span of a couple of months or years, as the chronology of these events would be emphasized. However, this requires defining precise event dates, which are not always available or agreed upon by historians.

The references used to specify the times of the events and their descriptions are listed in the source code of the Timemap, under the Sources fields. The source code is available here and is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Creative Commons License