Georeference Library Digital Collections Using Allmaps

Topics covered by this guide

  • Select a map to georeference from the Harvard Libraries’ digital collections
  • Repeat the process for maps in any library digital collection
  • Learn how to georeference with free browser tool, AllMaps
  • How to use the georeferenced map with the rest of your project

Select a map to georeference from the Harvard Libraries’ digital collections

  1. Find the map you would like to work with in the Harvard Libraries Digital Collections
Filter results by selecting Type: Map or Repository: Map Coll (Pusey)
  1. In the top-right corner of the image viewer, select the metadata Tooltip by clicking the i icon. Digital collections image viewer with a red box around the metadata Tooltip represented by an i icon in the upper-right corner

  2. Scroll to the bottom of the popup window and under Links → Manifest, copy the manifest URL.

Example IIIF Manifest

Digital colletions image viewer with metadata tooltip open, showing a highlighted manifest URL
  1. Navigate to the Editor
AllMaps is a free, open-source software for georeferencing maps in the browser.
  1. Paste the map’s IIIF manifest URL into the input box and select Load. Screenshot of the editor input box with the map manifest URL pasted in.

Repeat the process for maps in any library digital collection

It is necessary to copy one of these links, called a IIIF manifest in order to georeference the map using AllMaps. Most libraries host their digital maps using IIIF, but they don’t always put the manifest link in the same place.

For example, in this guide from the Library of Congress, librarians instruct you to scroll to the bottom of the page to find the link.

Screenshot of LOC IIIF instructions. Get Started Guides: Library of Congress

If you only plan to use maps from the Harvard Map Collection in your project, you can skip this section and head to learn how to georeference with free browser tool, Allmaps .

If you plan to georeference maps from many different library collections, it might be worthwhile installing the chrome extension, detektIIIF2 . This extension will generate the correct link for georeferencing, regardless of which library’s collections you are using.

Using detekTIIIF2

  1. Install the extension .

  2. Visit a map in a digital collections. There are over 19,000 maps digitized in the American Geographical Society Library (AGSL) digital collections .

Screenshot of LOC IIIF instructions. Map of Louisiana in the AGSL digital collections .

  1. With the detektIIIF2 Chrome extension enabled, click on the extension from your Chrome extensions list.

Google Chrome extensions

  1. Here, you can copy the manifest URL to your clipboard, which you can paste into the AllMaps editor . Detektiiif manifest copier

  2. If a manifest URL isn’t immediately detected, trying expanding the map viewer. For example, in the Leventhal Map and Education Center digital collections – which feature nearly 12,000 digitized maps, many of Boston, Cambridge, and New England – you must expand the map viewer to full-screen for the detektIIIF extension to work.

expanding the map viewer to big

Once the viewer is expanded, when you click the detektIIIF icon and pan over to the IMAGES tab, you’ll find a link you can copy into the AllMaps editor. images tab in detektiiif

Learn how to georeference with free browser tool, AllMaps

Use the mask tab to crop out marginalia, if necessary, and the georeference tab to assign control points between the map on the left, and the baselayer on the right. Start with at least three control points, evenly distributed at equidistant spots around the map. You can add a few more, for more specificity. Click the results tab to check the results. Screenshot of a map being georeferenced in the AllMaps editor.

Right now, AllMaps works best for larger-scale maps, or maps that show a smaller area, in more detail. If you need more robust transformations for small-scale maps, you might try one of our other georeferencing guides. Learn the difference between small and large scale maps.

How to use the georeferenced map with the rest of your project

Once you have finished georeferencing your map in AllMaps, click the Results tab. AllMaps is now hosting your georeferenced map as a GIS web layer you can use in any project. All you will need is the layer link. You can find it on the Results page: Allmaps layer link

Ideas for using the map in your project

Add the layer to a QGIS project

  1. Open QGIS. If you need to download the free desktop software, learn how to do so here .

  2. Open a new project.

  3. In the Browser window, under XYZ Tiles drag OpenStreetMap into the map canvas window. GIF of adding a basemap to QGIS

  4. In the Browser window, right-click XYZ Tiles and select New Connection. Screenshot of QGIS browser menu

  5. Name your map, and paste in tile URL you copied from the AllMaps Results panel. Select OK. Screenshot of QGIS New XYZ Tile Connection menu

  6. In the Browser window, under XYZ Tiles, double-click the new connection item you just created to add it to the map.

  7. Zoom in to your area of interest using the zoom controls in the banner menu across the top of the program. As you zoom in, your georeferenced map should appear.

Tip: it may take a second for the quality of the tiles to resolve. GIF of zooming in on the map

  1. To adjust opacity of your map, right-click the map layer in the Layer list and select Properties. Screenshot of opening layer properties in QGIS

  2. Under the Legend tab in the Properties menu, highlight Opacity Slider and use the right-pointing arrow to move the widget from Available widgets to Used Widgets. Screenshot of Legend tab in QGIS layer properties

  3. Select OK. There should now be an opacity control under the map layer item in the Layer list. GIF of using the new opacity control in the QGIS layer list