Bring Your Maps into Focus: Processing Raster Data for Online Use
Have you seen georeferenced historical maps online that just look...fuzzy? That’s what we started with at the Emory Center for Digital Scholarship, and we would like to share the steps we’ve found to get clear, legible, zoomable map overlays.
- First we will discuss different specialized file format options for saving these maps and their associated geospatial metadata and the advantages and limitations of each.
- Second, we will cover the processing required to get map images to display clearly at multiple zoom levels. This will include a discussion of reprojecting maps, tiling, and adding overviews. We’ll show examples of some of the roadblocks we ran into while working through this process.
- Finally, we will discuss storage options for these files such as Geoserver or static tiles and use in web mapping programs such as Leaflet and OpenLayers.
Working out this process has taken a lot of collaboration among specialties (librarians, software engineers, GIS specialists), across institutions, and from multiple online sources. We’re hoping that laying out this process in one place will help others share their map collections online.