OCRA

OCRA is a collaborative web platform for annotating, documenting, and semantically enriching cultural heritage assets in 3D and relightable 2D environments. Developed within ECHOES as a Vertical Application of ECCCH, it combines advanced visualization, structured annotation, real-time collaboration, and semantic interoperability for conservation-restoration, technical art history, archaeology, and digital heritage. 

OCRA is a multi-view annotation environment that integrates: 

• ThreePresenter for interactive 3D inspection and annotation workflows on digital models;
• OpenLIME for 2D and RTI / relightable image exploration and annotation; 
• a structured annotation backend designed to preserve semantic consistency, collaborative safety, and long-term interoperability. 

At its core, OCRA uses a decomposed annotation model that separates each annotation into three connected entities: 

• the geometry that defines the spatial anchor; 
• the data that stores the semantic or documentary content; 
• the link that explicitly associates geometry and meaning. 

This model makes annotations reusable and auditable: a semantic record can describe several spatial regions, while one spatial anchor can support multiple interpretations. It is particularly useful in interdisciplinary work, where experts may interpret the same evidence differently. 

OCRA supports collaborative, concurrent work. Optimistic Concurrency Control (OCC) prevents conflicting writes, while real-time server events notify connected users of committed changes and active editing contexts. Lightweight social locks signal when someone is present in a scene or editing an annotation, reducing conflicts without rigid blocking. 

Structural project operations use stricter coordination. A dedicated structuring lock protects scene creation, asset association, composition changes, publication, and destructive maintenance, preventing invalid spatial references or inconsistent project states. 

OCRA integrates with the EGI authentication ecosystem used by ECCCH, providing federated access for cross-institutional collaboration. It also reads from and writes to ECCCH triple stores, including OCRA-specific payloads for interoperable project export, publication, re-import, and preservation. 

The platform includes a vocabulary-driven semantic layer for annotation ontologies and controlled terms. Some vocabulary sources are still simulated or transitional, but the model, APIs, and workflows are ready to integrate authoritative terminology and ontology services. 

OCRA can also import heritage metadata from ArCo and Wikidata, and metadata and 3D assets from sources such as Europeana. Projects can therefore build on existing cultural heritage records, improving semantic alignment and reducing duplicated work.

OCRA is under active development as a Vertical Application of the ECHOES project. Its architecture, workflows, and user-facing capabilities will continue to be refined throughout the project. 

Its current feature set includes: 

• Collaborative annotation of 3D models, 2D images, and RTI / relightable images in the browser.
• Integration of ThreePresenter for 3D visualization and OpenLIME for relightable image workflows.
• Structured annotation model based on geometry, data, and explicit links. 
• Real-time collaboration through mutation broadcasts and shared annotation awareness.
• Social locks signalling user presence and active editing. 
• Optimistic Concurrency Control (OCC) to prevent conflicting writes. 
• Structuring lock for scene, asset, and publication changes. 
• Project environments with configurable scenes, assets, semantic vocabularies, and annotation scopes. 
• Semantic enrichment through controlled vocabularies and ontology-aligned data structures, ready for connection to authoritative terminology services. 
• EGI / ECCCH authentication for federated access across institutions. 
• ECCCH triple-store integration for reading, publishing, updating, and re-importing Heritage Digital Twin data. 
• Import of metadata from ArCo, Wikidata, and related sources. 
• Import of metadata and selected assets, including 3D resources, from Europeana. 
• OCRA payload export/import within ECCCH publication workflows for continuity between local and cloud instances.

A conservation-restoration team is preparing the documentation of a heritage object that includes 3D survey data, relightable technical images, and descriptive metadata from institutional catalogues.
A project manager creates an OCRA workspace, authenticates through ECCCH, imports heritage metadata from sources such as ArCo or Wikidata, associates 3D and 2D/RTI assets with project scenes, and configures vocabularies and ontology-driven terms. During structural reorganization, the structuring lock protects scene and asset changes.

Conservators, curators, and researchers can access the project simultaneously from different institutions. One may study a 3D surface through ThreePresenter while another examines relightable images in OpenLIME. Contributors create spatial anchors, add semantic content, and refine records; real-time updates and social locks improve awareness, while OCC prevents silent overwrites.
OCRA can publish the resulting knowledge to ECCCH as semantic graph content and OCRA-specific project payloads. Annotations thus become interoperable, reusable, and preservable research assets within the broader Cultural Heritage Cloud ecosystem.

OCRA benefits directly from being connected to ECCCH.
ECCCH provides federated identity for secure collaboration across institutions and countries, together with the knowledge infrastructure needed to align annotations with shared semantic models, controlled vocabularies, and heritage metadata standards.

Through ECCCH triple stores, OCRA can read, publish, update, and re-import Heritage Digital Twin data while preserving the payload needed for continuity between instances. OCRA therefore produces interoperable, FAIR-oriented documentation that can circulate within the European Cultural Heritage Cloud.

By combining structured annotations, collaborative safeguards, 3D and relightable 2D viewers, semantic enrichment, and cloud publication, OCRA provides a comprehensive environment for creating, managing, and sharing conservation and heritage documentation.

• OCRA
• ThreePresenter
• OpenLIME