This week, I familiarized myself with digital mapping technologies to fully understand the possibilities that combining historical map data with modern visualization software can accomplish. Specifically, I used the David Rumsey GIS. This tool accesses numerous historical maps that predate modern mapping technology and allow the user to manually reference landmarks to judge the accuracy of the primitive maps and superimpose the image on contemporary maps.
The map I focused on was of southern France, named Govvernemét de Montauban. It included its distance key in the bottom right and was not a large-scale map covering much of France.
For the user, selecting specific map points found in the accurate modern map to the primitive map is simple. You are allowed any number of points to connect similarities, and more similarities allow for a more accurate superimposed final product.
Furthermore, once you have your points selected, there are enumerable options you can decide to do with your map data. For one, it is interesting to visualize your map as an image overlaid upon the updated modern map. You can always adjust the opacity of the map to view its accuracy, given that it was illustrated several centuries ago.
As can be seen in the images above, the town and river locations have noticeable inaccuracies, but the overall functionality of this old map would be sufficient. It certainly had accurate general locations without the technology to view the world from a bird’s eye. This technology would allow historians to understand further how maps were made and gather data based on those observations. When maps such as this one are slightly incorrect in exact location markers, we can ask questions such as what limitations were presented which caused this map to be skewed. We can speculate whether physical boundaries, such as environmental landmarks, prevented accurate records.
The map only covers this limited area of Southern France.
Due to human error on both sides, these digital mapping resources would not be very useful if accuracy were a factor in a user’s end goal. The technology provides accurate location references to a degree, and human-selected points on the modern map can also be slightly inaccurate. Additionally, cities may expand and shift after centuries, causing mapping data to be inaccurate for those reasons which may hide information about what the area once looked like. However, these tools still allow modern people to take a glance into what the world once looked like from the eyes of historical cartographers.
2 thoughts on “Mapping Blog”
Comments are closed.
I had not thought seriously about how adding the digital rendering of the map adds on another level of human error and bias but it is definitely another factor contributing to the ways that inaccuracies can be introduced. You mention that the changing nature of cities can cause further inaccuracies that could hide information about what areas might have looked like in the past. I wonder if this remains true when you are able to so closely match locations and enable different opacities to let the viewer see both the old and modern map. I think this has the potential to maybe even increase the amount of information about the past.
I also found that accuracy was difficult to achieve with this software. I came to the same conclusion that this cannot be used to accurately describe the geography but rather just display the similarities in an overlay fashion for the old maps and modern base map. I am curious how you found the specific area of France that this map aligned with. Were the names the same on the base map?