App AR VJECT – view BIM models on site with an iPad
App AR VJECT (VjectAR, project PA3 Hybrid AR) was developed by SDC, Institute of Information Technology in Civil Engineering (IIC), for the client VJECT. The app overlays the BIM model and the electrical, plumbing, HVAC, fire protection and underground systems in their true position on site at 1:1 scale, located by surveyed QR markers.
From an IFC file in the office to pipes shown behind the ceiling
The modelling team hands over the IFC file and a table of QR marker coordinates. On site, you point the iPad camera at a QR marker: the app knows where the marker sits in the project coordinate system and places the model in the right spot. The app does not use phone GPS to place the model, because GPS is only accurate to a few metres.
- Site mode: the BIM model overlaid on reality at 1:1, locked to the QR marker
- Office mode: a scaled-down model on the table top; rotate 360°, zoom, tap to inspect elements
- Outdoor GPS guidance: see above-ground and underground infrastructure by bearing and distance
- Tap an element to see its code, type, specifications, manufacturer, installation year, warranty, status and depth
- Colour by discipline or element type, adjust transparency, and let real objects occlude the model on LiDAR devices
- Measure in AR, capture photos of the model over existing conditions and send feedback linked to an element
Choose a mode by where you stand and what you need to see
The app always shows which positioning method is in use, because their reliability differs widely.
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Indoors · QR marker
Scan a QR marker fixed inside the building. The model is placed from the marker coordinates taken from Revit, at 1:1.
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Outdoors · surveyed marker
Scan an outdoor QR marker whose coordinates were measured with RTK (WGS84). This is the only way to get below 1 m error outdoors.
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Outdoors · geo anchor
Uses ARGeoTracking where Apple supports it, combined with the project's surveyed origin.
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Outdoors · GPS only
Before a marker is scanned: guidance by bearing and distance; the app states clearly that this is not 1:1 and shows an error circle.
What the modelling and survey teams hand over
The model only matches the site when the delivered data follows the project's data contract. The app comes with two documents: a BIM export standard for the Revit team and a georeferencing guide for the survey team.
| Item | Requirement |
|---|---|
| IFC file | Origin at the Project Base Point, units in metres, Z axis up; do not swap axes yourself before export |
| Three survey points P0, P1, P2 | File project_georef.csv; axis direction derived from the two RTK points P0–P1 |
| Indoor QR markers | marker_code, floor_level, position_x/y/z (m), rotation (degrees), physical_width_m |
| Outdoor QR markers | Coordinates measured with an RTK rover, WGS84 |
| GPS POI | WGS84 coordinates, ground level and depth of underground items |
The server converts the IFC file to a 3D model and converts axes from Revit's Z-up
system to ARKit's Y-up system with X_app = X_bim, Y_app = Z_bim,
Z_app = −Y_bim. The content printed in the QR code is exactly the
marker_code value. A 1° error in axis direction shifts a point 500 m from
the origin by about 8.7 m, so the survey step is the most important one.
Viewing a BIM model on site with App AR VJECT, step by step
1. Sign in and open a project
- Sign in with the account issued by the project management board. An account not yet assigned to a project sees a message asking it to request access.
- The home page lists recent projects. Each shows its number of QR markers, number of GPS POIs and the BIM models loaded.
- Open a project to see its address, origin coordinates, number of storeys and VN2000 zone.
2. Choose a viewing mode
- Tap Scan QR for accurate viewing from a QR marker, or GPS guidance to see outdoor infrastructure by bearing and distance.
- With QR, choose Site mode (1:1) or Office mode (table).
3. Scan the QR marker and check tracking quality
- Point the camera at the QR marker. Once the code is read, the status bar changes to Locked to marker.
- Watch Tracking quality. If it reports a surface that is too plain or too dark, aim the camera at an area with detail and move the device slowly.
- If the model is offset from the site, open Fine-tune to nudge it in 10 cm steps, or tap Re-anchor.
4. View and filter elements
- Toggle each model layer and set Colour by original material, by discipline or by element type.
- Drag Model transparency to see through it; on LiDAR devices, turn on Real objects occlude model.
- Tap an element to open its information panel; tap View on map to locate it on the Map tab.
5. View a table-top model in the meeting room
Choose Office mode, place a printed QR code on the table and point the camera at it. The model appears as a table-top model: rotate 360°, zoom, tap for information and adjust Model size.
6. Send feedback from site
- Tap the problem element and tap Report issue, or tap Capture & feedback to photograph the model over existing conditions.
- Enter a description and choose the priority Low, Medium, High or Urgent. The project, marker and element are attached automatically.
- Without a connection, the ticket is stored on the device and sent when the connection returns. Track its status, Pending review, In progress or Resolved, on the Feedback tab.
Developers and ownership
- Name
- App AR VJECT (VjectAR) – PA3 Hybrid AR
- Version
- 1.0
- Developed by
- SDC – Institute of Information Technology in Civil Engineering, Hanoi University of Civil Engineering
- Client
- VJECT
- Ownership
- Under the contract between the Institute and VJECT
- Platform
- iPadOS and iOS (ARKit, RealityKit); LiDAR devices also get occlusion
- Data exchange
- IFC, CSV for QR markers and GPS POIs (project coordinates, WGS84, VN2000); photos and feedback tickets through the server API
Need to take your project's BIM model to site?
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