Blending The Past And The Present With Interactive Mapping

It wasn’t all that long ago that we were writing about how much mapping has changed in the last decade compared to the last few centuries. Map collector David Rumsey has been busy putting up 120 maps from his collection of more than 150,000 historical maps online. All of the maps can be downloaded for personal use through creative commons licensing. What is most interesting is that he isn’t just posting these maps online for anyone to use, but he is laying them on top of Google Maps.

Some of these maps fit perfectly overlaying their modern location while others, generally the earlier period maps, reveal interesting tidbits of geographical misconceptions of the time they were created. David Rumsey’s site describes the process as follows.

The original historical maps are first made into digital images by scanning them with high resolution digital cameras. Then these digital images are transformed in a process called georeferencing, which makes them display in their correct geographical spaces in Google Maps and Earth. Georeferencing is done using a GIS program, which takes points on the old maps (cities, coast lines, rivers, streets) and connects them to the same points on a modern satellite map image or a modern street map or a modern map showing boundaries of countries and states. The GIS program then takes all these points (as many as 200 are made for very large maps) and uses them to recreate the digital image so it will fit into its modern geographical space. Often the image has to be curved a bit for this to be accomplished.

You can view a nice interactive world map that allows you to choose from one of these over a hundred locations. By clicking on any location you are provided with a summary of what the map is, and then you can view it to see the map overlaid with modern satellite photography. The maps range from 1680 to 1930 and show scales and cartographic art. The georeferencing provides an extremely accurate overlay.  Really cool stuff!

This is a fascinating example of showing the history of mapping from its earliest roots into its much more modern digital age. Mapping techniques have come a long way. We hope you enjoy playing around with the interactive map as much as we did.