[Qgis-user] Building Historical Maps

[Phil Wyatt]

Hi James,

By the sounds of the project I suspect you will get very good at snapping, tracing, merging and digitising from old maps. There are good tutorials on georeferencing old maps and digitising from them. Your other option will be to search out other projects that may have already done some of this work for you but honestly, pre the 1990's you will likely struggle to find ORIGINAL digital files unless you can get contacts within the agency that was responsible for the original digitisation, and they have good archives. Depending on what maps you find it may be possible to do some raster to vector conversion.

Buckle in for a slow, long haul project!

Cheers - Phil

-----Original Message-----
From: Qgis-user <qgis-user-bounces at lists.osgeo.org> On Behalf Of James Cobban
Sent: Friday, 23 July 2021 10:29 AM
To: qgis-user at lists.osgeo.org
Subject: [Qgis-user] Building Historical Maps

I am running a project to present historical information about Ontario, Canada.  To support this I have imported GIS information on administrative boundaries from the Ontario Government.  The only problem is this information only describes the current administrative organization of the province, not the organization it had for most of its history up until the early 1990s when the system was "rationalized".  I am looking for suggestions of how to extract as much information from the current GIS data as possible.

For example:  From 1850 to the early 1990s most of Ontario was administered as counties with lower level townships.  In the 1990s the more urbanized portions of the province were reorganized as "Regional Municipalities" which largely ignored the old county boundaries either by including only the urban portion of a former county, or by incorporating urban portions of multiple counties. So, for example, if I wish to reconstruct the boundaries of the former county of Welland I have to concatenate the boundaries of the individual townships that made up the former county, and then remove all of the internal, and redundant, boundaries.  I have manually done that for one county but it was a pain in part because the polygons of the individual townships did not begin at a "corner" shared with an adjacent township within the county. Just finding exactly where the polygon began and which direction it went took time.

The second issue is that boundaries changed multiple times over the period between 1763 when Britain assumed control of the area of Ontario, and the present.  In particular city boundaries change as areas are transferred from the surrounding rural municipalities to the city as a result of urban growth.  Where do I get the old boundary information aside from tracing them from old maps?

--
James Cobban
911-500 Springbank Dr
London, ON, Canada
N6J 4G6
mailto: webmaster at jamescobban.net
+1-226-504-7603

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