BMT Defence Services : Aegir AR

Over the past six months or so we’ve been working closely with Bath based, BMT Defence Services Ltd and 3D visualisation experts Defence Imaging from Exeter; to develop what has to be the most cutting-edge use of AR we have personally been involved with.

The concept was simple enough; can a model of a boat be augmented?

Fortunately, metaio had just released their fantastic new AR software which has the ability to augment 3D objects. Without this, the task would have been a huge challenge as no other commercially available software came close to what was required.

The boat, well actually a ship, is called the Aegir. It’s a replenishment vessel design, a derivative of which has been bought by the Royal Navy, to take fuel and supplies to ships on patrol. When it meets up with a patrolling ship, it can replenish on the move, sending over fuel, oil, water and supplies by way of wire and helicopter.

Aegir and Type 45 Destroyer RASing

Aegir and Type 45 Destroyer RASing

The challenge was to turn the scale model of the Aegir; a one metre long, carefully crafted representation of the real thing, into an augmented reality experience showing its capabilities.

On the wish list were:
• Show the refuelling capabilities alongside another ship, a Type 45 destroyer.
• Show a helicopter taking off and flying around.
• Bring some crew members onto the deck.
• Add some pop-up information panels to highlight key features.
• Bring some crew members onto the deck.
• Add some pop-up information panels to highlight key features.

The Aegir was available as a 3D computer generated model, as were most of the other components we wanted to add to the scene from BMT’s library. We needed to align these 3D models with the scale model accurately and for that we had to work out the actual scale of the model and take some measurements.

As you can imagine, measuring something boat-shaped can’t be done with something as basic as a steel rule; I know, I tried and failed (and broke a piece off the model).

How not to take measurements

How not to take measurements

Without accurate measurements, the 3D Aegir which we needed to occlude other objects in the scene wouldn’t align and the whole illusion would break.

The occlusion model allows us to mask off areas that would otherwise show the 3D models. For instance, the helicopter needed to take off from the stern but there’s a massive bridge between it and the bow. If we didn’t have the occlusion, the helicopter would appear on the wrong side of the bridge when viewed from the bow, the sea would appear on top of the model and the crew members would appear to float in mid air. It was obvious it was required and we needed it to align perfectly.

Occlusion tests

Occlusion tests

Steel rulers aside, we called in some proper measuring equipment: BMT’s laser scanner. This created an accurate point cloud map which we could then take measurements from.

Laser scan output

Laser scan output

The measurements we received allowed us to align the 3D model and the scale model perfectly.

Another challenge we faced was dealing with a little used model format, .MD2. If you ask any 3D modeller or animator about .MD2, the chances they will have heard of it are fairly slim; the chances they’ve ever used it are even slimmer still.

It’s not an easy format to work with. It has many limitations but it works on smartphones and tablets and it’s the only format we could use for animations with the only software that provided 3D object tracking. Fortunately we could use a static model format .OBJ for the other bits.

Early 3D rendering

Early 3D rendering

It took some time to get right, but the animations of the helicopter and crew members finally fell into place. The helicopter takes off, does a loop around the Aegir before coming into land under the guidance of one of the crew. Meanwhile, two other crew members run onto deck to help with the replenishment and the 3D model of the Type 45 has a rotating radar and churns out a steady wake as it floats alongside the Aegir during the replenishment phase.

Almost complete AR scene

Almost complete AR scene

As an R&D project for BMT Defence Service it turned out to be a great success. What appeared to be an almost impossible challenge turned into a stunning example of augmented reality; limited by lesser known 3D model formats, device capabilities and a scale model that had to be sent off to exhibitions every so often.

The AR now works simply by pointing the iPad’s camera at the scale model, with the animated scene appearing before your eyes.

It has been exhibited and demonstrated to various groups, managers and VIPs and feedback has been amazing.

Its early days for this type of AR, and one day it’s going to look dated, but today it looks magical and shows the power of mobile AR computing at its best.

We’ll be adding up to date photos and a video shortly.

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