Georeferencing can be an extremely useful tool. Not only in the field of geospatial analysis but also in History, Humanities, and Languages. What I mean by that is this, say you come across an old map of Northfield and you want to compare it to how Northfield looks today. The best way to do this would be to georeference similar points on each map, then you can accurately compare it to the Northfield of today. Furthermore, let’s say you obtain the path that Jesse James took during his raid on the Northfield bank. Using georeferencing you could create a map that shows his path through modern-day Northfield. There are many problems one must consider when it comes to georeferencing. The most important being the coordinate system used on each of the maps, if the two maps have different coordinate systems it will be difficult to accurately align them. Another issue one may face is how time changes an area, it is possible that a map may show a town from 50 years ago that has changed so much that it cannot be accurately georeferenced. While georeferencing maps one must keep in mind that the best place to put the aligning points is at right angles. This way the points are less likely to shift slightly. A time when georeferencing would not be appropriate is when a map that has already been poorly georeferenced is used as the base map, this would lead to messed up results. This process did not really change my understanding of spatial digital humanities projects but rather reinforced all of the possibilities that it has.
The map I chose to georeference is a map of the Erin township in Illinois from 1871 created by Thompson and Everts. I chose this map because while it was rather blurry it had bold, clear lines that ran through it (likely an interstate). These lines made it easy to georeference the map as there were many right angles to use at points. Click here to see my georeferenced map!
2 thoughts on “Thoughts on Georeferencing”
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Wow, that is super cool that your map from 1871 had some roads on it that lined up with roads we still see in the same area today. I think that is a super cool application of georeferencing which allows us to see the way that some areas have stayed very similar over long periods of time. I also like your point that we need to be very careful about georeferencing off of a previously georeferenced map, as it can be really easy for small discrepancies to add up over time.
Hi Sydney, I think it is really helpful that you brought up the idea of putting the aligning points at right angles. I had a hard time alligning my maps because I could not find the appropriate points and I would definitely try your method next time. Also, brilliant idea that it is inappropriate to use georeference if the basemap is poorly georeferenced. I have never thought about the problem with the basemap!