Georectified Map of California

Georectified Map of California

Georeference seems to be an interesting tool as I worked throughout this process to connect the points on the image to the map of California. I searched for some of the popular cities in California such as Sacramento, San Francisco, and San Jose, and connected them to their corresponding geographic location on the map. This was an easy step. However, the next step was difficult for me because I had to capture the outline of the California map. Since the outline has many zig-zag lines along the edges, I had to add so many points to capture an accurate outline of the map. My favorite part was comparing the points on the image to their geographic location. The points that I connected seemed to match perfectly, however, there were some parts of the map that were not matching exactly with the points on the image. Therefore, I had to make a few adjustments to improve the accuracy of the map. The second time it was better, but I realized there is still room for improvement. I decided to work on it more in class.  

Throughout this process, I learned how useful spatial DH projects are in digitizing old maps and using them to compare and contrast with the modern map that is available online. This process helps us to identify geographical changes that could have happened over time. 

There are a few options on the top tab that allows the user to interact with the map and image simultaneously. The overlay format shows how well the image outline matches the outline of the map. There are some parts of the image that are off on the edges of the map. I enjoyed playing with the grid format because it helped me find how well the points on the image match the points on the map, which helped me to work on improving the accuracy of my image. 

Overall, there are many possibilities with a georectified map. For example, we can use it to analyze geographic information and features and how they might have changed over time. In addition, there could be errors, where the map outline is different from the modern map or the points on the image don’t exactly match with the points on the map due to differences that have occurred over time. Anyway, this is an interesting tool and I enjoyed learning how to use it.

One Comment

  1. Hi Ali, comparing and setting the control points were definitely my favorite part of georeferencing the map, too. I also agree that this could be a useful tool to compare the changes of geographical informations. However, I was curious how significant would the accuracy of the georectified map be since there are human errors and also there are cases when the maps aren’t accurate.

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