Locate a Manifest on a Web Map

Use Case

You have a photograph of the Laocoön bronze and you would like to show the current location of the bronze as a Point on a web mapping platform. navPlace allows you to place the spatial representation (Point, Polygon, LineString, etc.) of your Manifest on a web map.

Implementation Notes

This recipe describes the use of navPlace at a Manifest implementation level. For other applications, see related recipes below. It is important to note that navPlace is not semantic and cannot be used to state the purpose of the location it shows. The example uses navPlace to represent the current location of the item, but it is not specified or limited to that, and more accurately we can say that navPlace is used to show a location.

The value for navPlace is a single GeoJSON Feature Collection. A Feature Collection represents an aggregation of spatially bounded areas. A Feature Collection has a type property that must be “FeatureCollection”. A Feature Collection has a features list that contains GeoJSON Features. Each Feature type has coordinates that corresponds to a shape such as a Point or Polygon. An id is not required in an embedded Feature Collection, but is required when the value is a referenced Feature Collection.

Note that GeoJSON specifies coordinates be recorded in Longitude, Latitude order, but Google Maps will display coordinates in Latitude, Longitude order. Always confirm the order of your coordinates when gathering them, as other web mapping platforms may have these format inconsistencies.

For technical specifics on implementing the navPlace property see the implementation notes in the IIIF Extensions directory. You can also refer to the IIIF Guides entry for step-by-step hands-on details on implementation.

The navPlace property is not processed by the Universal Viewer or Mirador viewer at this time.

Example

The map shows the location of the object represented in the image, the Laocoön bronze by Giovanni Battista Foggini, on display at the Getty Center. The Manifest contains one Canvas with a photograph painted onto it. The navPlace property in the Manifest stores geographic information about the bronze in the photograph, in this case the bronze’s current location. navPlace contains GeoJSON-LD, and a client can parse GeoJSON features from navPlace. These GeoJSON features are rendered as geometric shapes by web mapping platforms. Data from the resource such as an image URL, label or summary is connected with those shapes via properties in GeoJSON, but this is not a required step for seeing the shape on the map. To see an example using a polygonal shape see Represent Canvas Fragment as a Geographic Area in a Web Mapping Client.

JSON-LD

master [0021]: https://iiif.io/api/cookbook/recipe/0021-tagging/ “Simple Annotation — Tagging”