Georeferencer Tutorial

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A Gif Tutorial

Go ahead and open up a random map.
You will notice a window on the left with a historical map from the American Geographical Society Library, and a window on the right with OpenStreetMap. Feel free to change the contemporary map to your preference, but for now let’s keep it and drag the mouse around the historical map to learn more about it. Looking for landmarks and street names can be useful to proper Georeferencing, especially if you don’t immediately recognize the map.

Let’s try it out with another map. It is clearly labeled Wisconsin, with a distinct Western border. We can search “Wisconsin” to find the place and get a closer look on our contemporary map.

Here’s a map that has already matched the contemporary window to the historical. We have to place at least three control points, by clicking a point on the historical map to and matching that point on the same point on the modern map. Adding even more will improve the map’s accuracy, so don’t hold back.  Try to ensure your points are spread throughout the map.

Placing control points is the most important step: good control points include corners of buildings, intersections between streets and railway tracks, monuments, even unchanged borders. Avoid placing points along coastlines or other natural boundaries that may change over time.

Next, you’ll be prompted to clip the map’s area.

When you try to save your project, you will ba asked to create an account. The easiest way to set one up is with your google or social media accounts. Now you can track the maps you’ve Georeferenced and remember your favorites.

Once you save your project, explore the new ways we can visualize historical locations in a modern context. How have we changed over time? Are city blocks now parks? Was your favorite shop previously tenement housing? Are streets wider? Were borders different? Which features remain the same?

Have fun Georeferencing and don’t forget to share with your fellow #mapPeers! Get started here.