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Subject guide

Maps in the Crowd

Contribute to the progress of academic research by joining our geocrowdsourcing project of old maps from our Special Collections. The most active contributors will gain a spot in our library’s ‘Hall of Fame’ and will be rewarded with a special price. Read more about it on our blog.

Our Special Collections houses a large map collection. We'd like to extend its public usage by launching a special application that enables users to match the old with the modern topographical landscape. This technique is called 'georeferencing'.

A total number of almost 7,000 digitized topographical maps from the collection of KITLV (Royal Netherlands Institute of Southeast Asian and Caribbean Studies) has been made available. They largely contain 19th and 20th century material of Indonesia, Suriname, the Netherlands Antilles and Southeast Asia.

The special application 'Georeferencer' will show a scan of an old map next to a Google Map view. The old map has to be geographically linked to the modern map by assigning at least five corresponding control points. Afterwards the georeferenced map will be displayed as an overlay in Google Maps.

Follow the progress and the ranking of the most active contributors on our special blog. After completion of the project the winners will be announced and rewarded.

1. See a video explanation of how it works.


2. By clicking the 'Fix the location on a map'-button, you will be assigned a map at random. In the application, the historic map will appear on the left; a modern map will appear on the right.

3. Log on by using email/password (necessary to register upon first use) or social media account (Facebook/Google/Twitter).

4. Zoom into the old map enough to read it, and then find the corresponding location on the modern map. Use the gazetteer at the top if necessary. Click on the "This map" tab for more information.

5. Click on one map to assign a point, the assign a point at the same location on the other map. Look out! Check that the correct points are linked together.

6. Assign as many points as you can, distributed as much as possible over the entire map (minimum of five).

7. Define the content area of the map by "clipping" the borders.

8. Click the red "Save" button in the upper right when you are finished. Now, you can see the overlay of the georeferenced map.

Detailed instructions (LINK ONTBREEKT)

Map finder: https://www.google.com/fusiontables/embedviz?q=select+col7+from+1XX0cpWxcj9yiJyrHA8ACR5TUMTTUHJrDIR_gUA_Y&viz=MAP&h=false&lat=10&lng=0&t=1&z=2&l=col7&y=2&tmplt=2

Top 10 contributors: http://leiden.georeferencer.com/api/gadgets/top-contributors/table/leiden/KITLV_Heritage_Collection

Georeferences: http://leiden.georeferencer.com/gadgets/thumbslider/index.html?col=leiden&sql=SELECT+id,date_time,title,thumbnail+FROM+1XX0cpWxcj9yiJyrHA8ACR5TUMTTUHJrDIR_gUA_Y+WHERE+status+=+'georeferenced'+ORDER+BY+date_time+DESC