category: User Guide title: Exhibition digital twin - live data, simulation, analytics and recommendations

Exhibition digital twin

An Exhibition Space in Heratio is more than a 3D model of your gallery. When you feed it live or periodic readings from the real space, it becomes a digital twin: a virtual copy that you can monitor, simulate and forecast against the physical room. This guide covers the twin features that sit on top of the builder and walkthrough.

The building blocks

• Builder (/exhibition-space/{slug}/builder) - drag objects onto the floor or hang them on walls; set size, tilt and which wall (including the front or back face of an interior divider). Doors you place in the plan editor, and doorways between adjoining rooms, show on the floor and wall views. In Wall view you can also add windows to the selected perimeter wall - click Add window, drag it along the wall to position it, and click a window to edit its width, sill and height or remove it (windows can also be added in the plan editor); they appear as glass openings in the 3D walkthrough.
• Plan editor (/exhibition-space/{slug}/plan) - arrange rooms of a building on a blueprint; rooms snap to each other and can take custom (non-rectangular) shapes.
• Walkthrough (/exhibition-space/{slug}/walkthrough) - a first-person 3D tour on desktop and mobile. Move with W A S D or the arrow keys, wheel to step forward or back, and hold U + mouse wheel to stand taller or crouch.

Photoreal capture (scan a real room)

Instead of building a room block by block, you can back it with a photoreal 3D scan of the real space. In the builder, open the Photoreal capture card:

• Upload scan shell - a .glb, .gltf, .obj, .stl or .ply mesh exported from photogrammetry (e.g. RealityCapture, Metashape, Polycam) or a 3D scanner. It renders inside the walkthrough as the room's backdrop. The built floor and walls stay in place underneath, so you keep solid collision (you cannot walk out through a scanned wall) and a clean fallback if the scan is hidden.
• Fit scale - a single multiplier to size the scan to the room's real metres. The scan's own origin is placed at the room's corner; nudge the scale until it lines up.
• Your object placements and the live overlay still work over the scan - drop objects, hang pictures, run the conservation overlay exactly as on a built room.
• 360 / Matterport embed URL - paste a Matterport (or any 360 tour) share URL. A 360 button then appears in the walkthrough whenever you stand in that room, opening the immersive tour in an overlay. Licensing for the embedded tour stays with its host.

Point clouds render too: upload a .pcd or a point-cloud .ply and it shows as points in the walkthrough (large clouds are automatically downsampled so they stay smooth, on mobile too). .las / .e57 aren't read directly by the browser - export them to PLY or PCD from your scan software first. Larger scans take longer to download; keep them under a few hundred MB and decimate where you can.

Live data link

Readings of light (lux), temperature, humidity and visitor count can be recorded per room. In the walkthrough, press the thermometer button to turn on the Live overlay: each room is tinted green, amber or red by its conservation status, and a panel reads out the current room's values. Status is judged against the room's lighting-lux target and safe ranges for temperature (16-24C) and humidity (40-60%).

• Sensors or a building-management system POST readings to the room's readings endpoint.
• To see how it looks before any sensors are wired, use Simulate live data in the builder header to seed demo readings across the building.

Binding a real sensor (#1188)

Each space has a sensor token so a real IoT sensor or gateway can push readings without logging in. Open Analytics (logged in) to see the token, a ready-to-use curl example, and a Regenerate token button. A device just POSTs to /exhibition-space/sensor/ingest with the X-Sensor-Token header and a readings array of {metric, value} (metrics: temp_c, humidity, lux, visitors).

When a reading is out of conservation range (temp 16-24 C, humidity 40-60% RH, light at or below the space's lux target / 200 lux), Heratio raises a conservation alert shown at the top of Analytics, marked warning or critical. The readings also drive the live overlay, forecast and analytics as before.

Conservation forecast (simulation and prediction)

Open Forecast from a space to see, per room, the projected annual light dose from the recent average lux, compared with conservation budgets for sensitive, moderately sensitive and durable material. Each room shows the percentage of budget used, the days until the budget is reached, and a risk band. A what-if simulator lets you try different lux levels, daily display hours and target tiers.

The Conservation time machine on the same page is a top-down plan you can scrub through time: drag the slider and each room shades green / amber / red by its conservation status on that day, from the readings history. Drag past "today" and the rooms carry their current status forward as a projection - a quick way to see how conditions have moved and where they are heading.

Analytics dashboard

Open Analytics to see per-room trends for lux, temperature, humidity and visitors over the last 1, 7, 30 or 90 days, with summary statistics. Use it to spot drift, busy periods and rooms that need attention. This supports continuous improvement of the space.

The Visitor heatmap there shows a top-down plan of the building with each room shaded by how long visitors spent in it (cool = less, hot = more), and dots over the objects that drew attention. It is built automatically from real walkthrough usage, so you can see at a glance which rooms and objects engage people and which get overlooked.

Per-object attention. Each object dot is sized and shaded by dwell - how long visitors actually lingered on that object (captured as they open it in the walkthrough), not just how many times it was opened. A large, solid dot draws and holds attention; a small, faint dot was seen but skipped past. The object list below the heatmap shows views . dwell side by side, so an object with many views but little dwell - one that catches the eye but loses interest - stands out immediately. Use it to decide what to move to eye level, relight, or reinterpret.

In-twin recommendations

While walking through, a "You might also like" strip suggests related objects. Click a suggestion to glide to that object. Suggestions are based on how object titles relate to each other, optionally enriched with AI-generated reasons. Curators can pre-generate AI recommendations from the builder.

Hear an object described (audio docent)

In the walkthrough, hold T and click an object to have its description read aloud. If the object has no description recorded, Heratio asks the AI gateway to generate a short docent description on the spot, reads that out, and marks it in the panel. To force a fresh AI description even when one exists, hold G and click. Press Esc to stop.

Choose the speaking voice under the Controls panel (the ? button) -> Narration voice; on most phones and Macs the system neural voices are available there.

Ask the docent (AI Q&A)

Open an object's panel (click it) and use Ask the docent about this - type a question, or tap one of the suggested chips ("Tell me about this", "Who made it?", "When is it from?", "Why does it matter?"). The AI answers grounded in that object's catalogue record and reads the answer aloud. It will not invent dates, names or provenance that are not in the record - if the record does not say, it tells you so. Press Esc first to free the cursor so you can type.

You can also ask the docent to take you somewhere: type "take me to the dresser", "where is the robot", or "show me the Benson portrait" and it walks you to the best-matching object anywhere in the building and opens its panel.

Multiple visitors and live guided tours

Several people can walk the same exhibition at once. Each visitor appears to the others as a named avatar that moves in real time (updated a few times a second). The People button (top-right) shows who is here; you can set your display name.

Logged-in staff can run a guided tour: press Start guided tour, and visitors get a Follow the docent button that tethers their view to yours (it releases the moment they move themselves). While leading, whatever object you open is spotlighted so everyone following is flown to it, and you can post a short message banner to the group.

Virtual reality (WebXR)

On a VR headset with a WebXR browser, a VR button appears in the walkthrough. Enter VR for room-scale, head-tracked viewing; the left thumbstick moves and the right thumbstick turns. On ordinary desktops and phones the button stays hidden and the normal controls apply.

Share and interoperability

From the builder, the Share & interoperability card exposes the exhibition in open standards any other system can read:

• IIIF manifest (/exhibition-space/{slug}/manifest.json) - opens in IIIF viewers such as Mirador or the Universal Viewer, and can be harvested by other institutions.
• 3D scene manifest (/exhibition-space/{slug}/scene.json) - rooms and object placements so another 3D viewer can rebuild the space.
• Linked data (/exhibition-space/{slug}/exhibition.jsonld) - a schema.org ExhibitionEvent for search engines and linked-data tools.
• An embed snippet to drop the live walkthrough into any website with an iframe.

Authored audio guided tours

Curators can pre-build one or more guided tours: an ordered route of objects, each with a script the guide reads aloud and a dwell time. Build them in the builder's Guided tour (audio) card - add objects, type the narration (or tap the wand to draft it with AI), set seconds per stop, reorder, and save. You can keep several named tours.

Visitors press the green Play button in the walkthrough (or pick a tour in the Controls panel when there is more than one). The guide flies you from object to object, speaks each script, waits, then moves on. A banner shows the current stop and text; Pause / Stop are there too.

On mobile, where walking is fiddly, a big Start guided tour button appears at the bottom of the screen - tap it and the tour drives the whole visit for you.

Graffiti / wall tags

Tap the spray-can button, then click a wall to leave a short graffiti tag. Tags pin flat to the surface you click. (The demo war room and AI room already carry a few.)

When you are signed in, tags are saved and shown to everyone who visits. When you are not signed in, tags are kept only in your browser for the current session - they let you doodle and try the feature without writing to the gallery, and they disappear when you close the tab. To remove a tag, switch on graffiti mode and click the tag.

Night mode (walk with a flashlight)

Press the moon button (or N) to switch the gallery to night. The room drops to a dim, moonlit ambient - fairly dark but never pitch black, so you can still make out shapes

• and a flashlight switches on that follows wherever you look. Press the button or N again to return to normal lighting. Great for a dramatic after-hours tour, or for picking out a single spotlit object in the dark.

Reading an object's details

Aim at an object and click it (or click a numbered button) to open its info popup. When the popup opens the mouse cursor is freed and lands on the popup, so you can click Close, View full record, or a related-item suggestion straight away. Click the popup's close button, click away, or press Esc to dismiss it - the view re-locks and you carry on walking without having to click back in.

All the walkthrough controls

What makes it a "twin"

A virtual model becomes a digital twin once it is linked to the physical space through real-time data and can be used to monitor, simulate and predict. With the live link, conservation forecast and analytics in place, an Exhibition Space meets that test: you can watch the real room's condition, test changes safely, and forecast conservation risk before it happens.

Roadmap

Further extensions under consideration: live cross-institution federation of exhibitions, and rendering .las / .e57 point clouds (a conversion step, issue #1183). Neural narration voice (issue #1168) and photoreal scan import incl. point clouds (issues #1156 / #1183) have shipped - see Photoreal capture and the audio docent above.

A WebGPU renderer (issue #1153) was trialled but not adopted: on the target three.js build it broke transparency (glass), alpha-cutout foliage (trees/grass) and billboards (labels/people) with no visible performance gain, so the walkthrough stays on the proven WebGL renderer. A standalone proof page (/exhibition-space/{slug}/walkthrough-webgpu) is kept for a future retry. VR therefore continues to work as before.

Server-GPU pixel-streaming (rendering console-quality scenes on a server and streaming video to the browser, issue #1154) was evaluated and deferred: it costs roughly one GPU per viewer, whereas the walkthrough already serves unlimited concurrent visitors at no server cost. It is only worth revisiting for a single kiosk or low-concurrency photoreal experience.

A WebGPU renderer (issue #1153) is being evaluated: open /exhibition-space/{slug}/walkthrough-webgpu for the proof page - it runs the room on modern three.js with WebGPU on capable devices and a graceful WebGL2 fallback elsewhere (a badge shows which backend is live). The main walkthrough still uses WebGL until that evaluation completes.

Publish to the RiC knowledge graph

The Publish to RiC graph button on the exhibition-space page adds the exhibition to Heratio's Records in Contexts (RiC) graph as a rico:Activity, so it sits alongside your archival activities and each displayed object lists the exhibitions it featured in.

When the space is tied to a catalogued exhibition, publishing now also records the activity's who, where and when:

• Had participant - the exhibition's curator, designer and organising body are added as people/organisations (RiC agents) that carried out the activity.
• Took place at - the exhibition's venue is added as a place the activity was held at (resolved from your venue record, or from the venue name/address on the exhibition).
• Has date - the exhibition's opening and closing dates are recorded on the activity and on each of the above links.

Only the details that actually exist are added - an exhibition with no venue, no named people or no dates simply skips those links. Publishing again is safe: it refreshes the activity and never creates duplicate participant or venue links.