Irish Vice Counties : the creation of a specific dataset on OpenStreetMap

I've been meaning to write about OpenStreetMap Ireland's townland mapping project for some time.

It's a wonderful example of how historical maps are of significant value in creating really useful data on OpenStreetMap which is just as relevant as it today as was in the past.

The immediate reason for writing about them is that I have been creating vice county boundaries for Ireland. In doing so I have not just been using the data, but the fantastic range of resources made available through the activities of the townlands project.

The Vice Counties of Ireland
My first complete draft of the boundaries on OpenStreetMap

An Early Map Grid

In my post on Woodland Cartography I noted with regret that I had not consulted the Shorter Science and Civilisation in China regarding cartography.

I've now read the relevant chapter, and was rather disappointed. Although there was a fair amount of information about surveying, there was very little about cadastral surveys. Elsewhere in the world they seemed to be a major driver for collecting information about trees and woodland in the past. (Subsequently, I've also had a peek in the relevant complete volume of Science & Civilisation in China, and it suffers from the same deficiency).

What was interesting was a map from the 12th century which shows China with a rectangular grid overlay.

The Yǔjī tú (禹迹图 following the footsteps of Yu).
A detailed map of China carved in the Song dynasty on a stele now in the Stele Forest Museum, Xi'an. The original image in the Library of Congress is a scan of a rubbing of the stele. This version has been converted to monochrome, inverted and normalized to enhance contrast.

My interest was piqued, because I had not given over much thought to the historical development of gridded map systems: other than to assume most kilometric grids originated from military needs. In fact a recent discussion revealed that the Irish Grid was created around the time of the Second World War, with an antecedent in the grid used on the GSGS sheets of out-of-copyright maps shown on the Irish OSM server.

One early and prominent grid is the township grid of 6 by 6 mile squares which overlays much of the Western USA. This was created in the early days of the Republic, but like many such cadastral systems was more a series of grids with different origins than a single grid (see the wikipedia article for detail). I've made a crude attempt to map one such township in Oregon, close to the ranch founded by my great-great uncle.

Similarly in Ireland, the initial survey for the 6 inch maps produced sheets on county lines; as did the equivalent, but much later survey in Great Britain. Probably the same happened in other places: quite local grids initially, with consolidation occurring later.

Coincidentally Mike Dobson discusses location grids in a recent post about what3words. His discussion not only places their use in a modern context, but also has more information on their origins.

City Stripping : building historical road layouts from todays data

Street map of Buenos Aires 1895 (plano de Basch)
Source: Wikimedia Commons

For at least one year I have been thinking about the best way to create vector streetmaps for different historical periods for the same city. The basic principle is simple: take the existing street layout and remove what is new! Essentially, this presumes that any current vector data will be more precise than digitising vectors from old maps.

I have even given the process a name: "City Stripping", but in practice my attempts so far have been less successful than I hoped. I think that  I kept too much existing OpenStreetMap data in my first attempts, because in practice I found it easier to re-trace the old data (as here for Tartu/Dorpat).

Woodland Cartography

This is an expanded version of my talk at sotm-eu:

I start by seeking inspiration from the many ways in which woods and trees have been shown on maps in the past, and then consider what elements we may want for OSM data, and how we might depict such elements.

History Workshop at SotmBaltics

On the Sunday morning of the State of the Maps Baltics Susanna Ånäs had organised a workshop on mapping historical geographies.

Getting the History mapping workshop underway
Senate Room, University Main Building, Tartu