Conservation Workflow (TSU)

See also

In the Extended Matrix language manual:

The Conservation Workflow is the EM Tools workflow for documenting states and transformations of a built object — decay, restoration phases, thematic surveys (e.g. material, surface treatment, damage patterns) — over and above the strict stratigraphic sequence. It is built around a dedicated stratigraphic unit type called TSU (Transformation Stratigraphic Unit) introduced in EM 1.5.

When to use TSU

A TSU describes a transformation that happened on an existing unit without creating a new physical body of matter. Typical cases:

  • conservation surveys (mapping deterioration phenomena, biological colonisation, salt efflorescence, …);

  • restoration interventions (consolidation, integration, cleaning);

  • thematic readings of a surface that do not fit the standard US/USV/USD vocabulary (e.g. material change without removal, re-pointing campaigns, polychromy phases).

If the transformation produced a new physical object (for example, a wall added on top of another) keep using the standard StratigraphicUnit types. If instead the surface is the same but its state changes, TSU is the right type.

Creating TSU Units

The TSU authoring loop mirrors the standard US one but uses the TSU type and a thematic proxy.

  1. Import the base model that the TSU will be drawn on (typically a high-resolution mesh from a 3D survey, see 3D Survey Collection: Level of Detail in Blender).

  2. Create TSU nodes in the GraphML in yEd by setting the node TYPE = TSU from the EM palette, or generate them in batch from em_data.xlsx. Each TSU node should carry a unique name (site_code.TSU_NN) and be linked to the US it transforms via the appropriate connector.

  3. Assign a proxy to each TSU. The proxy can be:

    • a surface proxy — a thin mesh draped on the model that marks the area affected by the transformation;

    • an annotation proxy — a point, polyline, or labelled shape when the transformation is localised.

    Use the Proxy Box Creator (annotation mode) or the Surface Areas panel to author surface proxies.

  4. Define the TSU properties. The standard set is:

    Property

    Meaning

    phenomenon

    The transformation observed (e.g. erosion, biological_colonisation, re_pointing, polychromy_layer_2).

    localisation

    Where on the host unit the transformation occurs (e.g. upper_face, mortar_joints, sw_corner).

    material

    Material involved if relevant (e.g. lime_mortar, patinated_surface).

    date_of_survey

    ISO date the transformation was recorded.

    These properties are written into the graph as standard Property nodes connected to the TSU. Add further domain-specific properties as needed (severity, intervention urgency, …).

Managing TSU Visualization

TSU proxies are best rendered with pattern-based materials so that different transformations are visually distinguishable on the model without hiding the substrate.

  1. Download the TSU material library (EM_TSU_materials.blend) from the download page and Append the materials into your scene.

  2. Assign a material to each TSU proxy. The library provides patterns for the most common phenomena (erosion, missing parts, biological growth, salt crusts, repointing, …); a TSU_generic material is the fallback.

  3. Apply pattern-based materials by phenomenon. The Visual Manager Properties mode can drive material assignment from the TSU’s phenomenon property automatically.

  4. Tune readability with the material parameters:

    • density — number of pattern repetitions per square metre.

    • thickness — line / dot width.

    • opacity — blend strength against the substrate.

    Density and thickness are exposed as material inputs; tweak them in the Shader Editor and save the result back to the library if you want the change to persist across projects.

Exporting TSU data

TSU information travels with the rest of the EM graph in any export format:

  • Heriverse — TSU proxies and their properties are included as standard stratigraphic units with type=TSU; the consumer application can render them with their own materials.

  • CSV / xlsx — TSU rows appear in the standard US tables with type set to TSU; properties are columns.

  • GLTF — TSU proxies are exported as separate meshes with the applied pattern material baked, when the Bake materials option is on in Export Manager.

Todo

Add screenshots — TSU node in yEd palette, surface proxy painted on a wall in Blender, Visual Manager → Properties mode driving TSU material assignment, and the resulting render.

See also