From 3D Models to Knowledge: Proxies and the Knowledge Graph
▶ From 3D Models to Knowledge: Proxies and the Knowledge Graph (~~4 min)
Prerequisites
The EM Data Lifecycle: Create, Manage, Enrich, Export, ../../../em-blender-tools-doc:tutorials/04-3dsc-site-scale
Overview
A 3D survey records geometry, not knowledge. The transition from photogrammetry to an EM happens by creating proxies — segmented volumes that represent stratigraphic units. EM uses a knowledge graph (not tables) allowing runtime queries, multi-temporal visualisation, and multiple interpretations.
The key transition: a 3D survey records geometry, EM records knowledge.
Key Concepts
A 3D model is a representation; a proxy is knowledge.
EM uses a knowledge graph — not tables — for richer querying and temporal support.
The same site can be represented at multiple epochs within one dataset.
Stratigraphy applies beyond excavations: buildings, mosaics, vegetation all have it.
Screenshots
Coloured proxy volumes overlaid on the 3D photogrammetric model.
Knowledge graph vs. flat table: the EM approach allows runtime queries and temporal layers.
The Colosseum represented at multiple epochs within a single EM dataset.
Try It Yourself
In the playground dataset, identify three proxy volumes and examine which stratigraphic units they represent.
Note
A video walkthrough for this tutorial will be available on the Extended Matrix YouTube channel.