Tutorials

Step-by-step tutorials for working on mapping projects using GIS methods and software.

View the Project on GitHub HarvardMapCollection/tutorials

How to georeference images in the HMC 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)

  2. 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

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

    Example: https://iiif.lib.harvard.edu/manifests/ids:12216977 If you are working with a multi-page book, or otherwise need help finding the manifest URL, contact us at maps@harvard.edu. Digital colletions image viewer with metadata tooltip open, showing a highlighted manifest URL

  4. Navigate to the AllMaps.org Editor

    AllMaps is a free, open-source software for georeferencing maps in the browser. It supports the IIIF framework.

  5. Paste the map’s IIIF manifest URL into the input box and select Load. Screenshot of the AllMaps.org editor input box with the map manifest URL pasted in.

  6. 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.

  7. Copy the manifest URL again, if you don’t already have it save to your clipboard. Digital colletions image viewer with metadata tooltip open, showing a highlighted manifest URL

  8. Navigate to the AllMaps tile server info page. Drop the manifest URL in the IIIF Manifest or Image URI input box. Screenshot of the Allmaps tile server info page with manifest input box.

  9. Click submit. Scroll down to make sure your map is appearing. You can adjust the opacity to make sure the georeferencing is lined up appropriately. Screenshot showing map overlay preview becoming more and less transparent

  10. Scroll down to find the tile URL for your map. You can use this link in any mapping software that accepts map tiles as a data source. In this tutorial we will show how to add the map to a QGIS project. Copy the tile link. Screenshot of the AllMaps tile server info page scrolled down to text that reads "To use the warped map in your geospatial software of choice, copy the following URL template:"

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

  12. Open a new project.

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

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

  15. Name your map, and paste in tile URL you copied from step 10. Select OK. Screenshot of QGIS New XYZ Tile Connection menu

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

  17. 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

  18. 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

  19. 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

  20. 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