Horosthesia links to the current Concordia Graph.
The ontology it indicates very nearly encompasses the relationships of metadata Descriptions, Texts, Objects, and Transcriptions that I'm working on for the APIS image repository. One of my open questions about this enterprise is the availability of URIs for the Objects (and Texts, really). The Images and Descriptions I'll be more-or-less in control of, but I want to avoid a scenario in which I incur responsibility for identifiers outside of my domain.
I am supposing that the custodian of the transcriptions in the DDb might be able to structure things in such a way that creates Text URIs to parallel the transcription URIs in the databank.
In any case, if that graph is augmented with a "depicts" relationship and an Image object, my conceptual work appears to be done.