SPATIAL COMPUTING

Inside DeltaARBIM

DeltaARBIM is our own AR BIM app: the IFC model on the real site through an iPhone or iPad, live on three job sites.

Published

23 JUL 2026

Author

Mayur Tanna

What we were trying to build

The idea sounds simple: point an iPad at a construction site, see the BIM model on the real structure, and catch the difference before it is covered. Plan versus reality. Anyone who has tried to build this knows how much work "sounds simple" is doing.

A construction site is one of the hardest places for AR. Light changes hour to hour. Dust and bare concrete give tracking little to hold on to. There is often no signal in a basement or a core. The model has tens of thousands of elements. And the person using it is walking, one-handed, in a hard hat.

How it works on site, in four steps

01Open the model. Load the IFC and pick the floor you are standing on.
02Scan the corner. LiDAR reads the floor and builds a grid from it. No markers, no QR codes.
03Drop the pin. One anchor ties the model to the building, and it holds as you walk.
04Compare. The real wall and the model on the same screen, one trade at a time.

From IFC file to model on site takes under a minute.

Challenge 1: Locking a large model to a real site, to about 2 cm

AR frameworks track a phone well in a room. A construction site is not a room: open edges, reflective surfaces, no landmarks, and a floor plate that changes every week.

Our approach uses what every site does have, a floor and corners:

LiDAR reads the floor and builds a reference grid from the real geometry.
One anchor pin at a known corner ties the model's origin to the building, with no markers, no QR codes and no GPS.
World tracking keeps it stable as the operator walks. If the overlay drifts, a two-finger reset re-anchors it in seconds.

On site, the overlay holds to about ±2 cm after tracking warm-up. That is enough to see a duct fouling a beam, a wall off its line or a missing sleeve. It is not a replacement for a total station where millimetres matter.

Challenge 2: Large BIM models on a mobile device

A real model is heavy. A hospital floor with every discipline is a lot of geometry for a tablet, and the app has to stay smooth while the user walks.

So the model is prepared before it is drawn:

Converted on import: the IFC becomes one mesh per element, grouped by trade (structure, walls, HVAC, water, electrical), so each layer switches on and off on its own.
Lighter geometry: heavy elements are simplified while keeping their shape, and very small or hidden parts are left out of the view.
Only what you need: the app loads the floor you are standing on, not the whole building, and does not draw what is off screen.
Cached on the device: once converted, the model opens offline in seconds the next time.

On an iPad Pro, a full hospital floor with all services, around 40,000 elements, opens in under a minute and stays smooth at 30 frames per second while you walk.

Challenge 3: Building on IFC without breaking the BIM workflow

AEC teams work in Revit, Navisworks and other tools. A site app that accepts only one format is dead on arrival.

We built around IFC, the open standard every one of those tools exports. Element IDs (GUIDs) and properties are preserved, so a deviation flagged on site points back to the exact element in the model. Nobody has to re-tag anything.

Challenge 4: Usable one-handed, in a hard hat, in bright sun

The interface is cut to what a site engineer needs while walking a floor: trade layers, re-anchor, flag a deviation, take a photo. Everything else is one tap deeper.

Buttons are large and contrast is tuned for daylight. Re-anchoring is a two-finger gesture, so it cannot be triggered by accident. Every action gives haptic feedback, because you cannot hear a tap over an angle grinder.

What the three sites used it for

DeltaARBIM is in use on three job sites in India: two commercial complexes and a hospital.

Site	What it was used for
Hospital, operating theatre wing	Rated walls, medical gas and HVAC services checked against the model before and after installation, to about 2 cm
Commercial complex 1	Ceiling-void MEP checked against the model before the false ceiling closed
Commercial complex 2	Wall and column setting out checked against the grid, and MEP shafts checked before they were closed

See it working

A walkthrough of DeltaARBIM on a live site, model against reality: watch the site demo.

Stack

Part	Technology
Devices	iPhone and iPad
AR	Augmented reality with LiDAR
Model format	IFC, from any BIM tool
On site	Offline, markerless
Coming next	Android

Where it goes next

Android release: already in development.
Deviation reports: export as PDF, and as BCF so issues open straight in Revit or Navisworks.
Shared sessions: two people see the same model on site at the same time.
Automatic deviation detection: the app compares the LiDAR scan with the model and highlights what differs.

Building an AR BIM or LiDAR app of your own?

DeltaARBIM is the product we use to prove the engine. The same team builds custom AR, LiDAR and BIM apps for construction companies, contractors and technology partners: site verification, AR checks before and after installation, room scanning to floor plans and 3D models, and IFC or DXF export.

Start small: a short pilot or proof of concept on your own model and site, before any long commitment.
iPhone and iPad first, then Android, on the same base.
You own it: on a custom project, the code is yours.
One team from the first prototype to the app on site, and support after launch.

See how we approach AR BIM development, spatial computing for enterprise teams and 3D reconstruction.