Introducing Spatial Anchors for Annotating and Georeferencing Historical Maps

This poster presents workflows developed in the Necessary Reunions project (https://necessaryreunions.org/), focusing on structured storing, processing, and visualizing of annotations on historical maps. It addresses a best-practice implementation of the Web Annotation Data Model for managing annotations generated from text spotting (via MapReader), transcription, and iconographic classification. The contribution demonstrates how these annotations are interlinked and connected to place representations in external knowledge bases. This integration is achieved through a workflow organised around placed reference points on the IIIF Canvas, which act as shared spatial anchors for all derived annotations. Using these reference points, toponym and geospatial iconography annotations are linked together and to canonical place representations in external geo-thesauri. These canonical entries often provide precise coordinates, which also allows for the automatic generation of annotations compliant with the IIIF Georeference Extension (https://iiif.io/api/extension/georef/), which, then implemented, by using AnnoRepo for storage and Allmaps for visualization, supports the systematic refinement and enrichment of existing, manually created georeference data. By integrating text and iconography with gazetteers, the workflow offers researchers a fine-grained, comprehensive view of how places were historically represented across diverse sources, enriching the contextual analysis of map collections.