Image courtesy of CENTRUS

Renovation for the nation: How HOK is helping preserve a national icon on Canada's Parliament Hill

At the heart of Canada’s Parliamentary complex is Centre Block: one of the country’s most iconic buildings and permanent home to Canada’s Senate, House of Commons, and Library of Parliament.
Today, Centre Block is a powerful symbol of democracy—a space where the interests of the nation are met, discussed, and protected. But Centre Block itself needs to be protected too, in order to preserve the landmark for future generations. That’s why, for the first time in its history, Centre Block is undergoing a complete rehabilitation: one of the most complex heritage restoration ventures ever undertaken in Canada. 
With the project currently scheduled to take place over the course of the next decade, a long-term vision is crucial: something that the architectural team responsible for the restoration, HOK, are taking to a whole new level.
Image courtesy of CENTRUS
Leveraging the power of Twinmotion and Unreal Engine, they’re creating VR walkthroughs that enable the Canadian government to explore a realistic 3D version of Centre Block in real time—as well as an interactive experience that can preview what the building will look like years into the future.
Image courtesy of CENTRUS

A virtual heritage

To do this, the HOK team began by deploying an Unreal Engine-based architectural visualization pipeline they’ve been using for years.

Besides helping one of the largest architecture firms in the world stand out, the pipeline also enables the team to build 3D versions of their architectural designs with the help of imported CAD data, creating a natural path from BIM to their next big idea. 

The data is first captured on location using a mix of Leica terrestrial scanners, high-resolution cameras, and hand-scanning hardware. Scenes are then reconstructed into point clouds and meshes using RealityCapture photogrammetry software—a recent addition to the Epic Games ecosystem.
Image courtesy of CENTRUS and Attilio Pusterla
“Of all the apps we have, RealityCapture is as used as Revit,” reveals Mark Cichy, Principal & Director of Design Technology at HOK. “We use it everyday. That's how important it is to this process.”

RealityCapture models are validated in Revit to ensure their scale works in 3D space, or optimized in Houdini for web and VR visualization platforms. They’re also further refined with Twinmotion, which is used to do everything from exploring circulation paths and entry corridor sequences to adding extra detail with the help of a library of realistic trees, plants, and people.
Image courtesy of CENTRUS and Attilio Pusterla
Once ready, the team moved on to Unreal Engine to prepare dynamic client presentations that ensured stakeholders could see the impact of design choices and iterations in real time. Unreal Engine development efforts also allow HOK to visualize every state of the building as it progresses through different stages of the decade-long project timeline.

Every stone, every step

In order to generate a virtual mock-up of Centre Block, both fixed and mobile heritage assets throughout the building first need to be scanned. So far, this has resulted in 100TBs of point cloud data and a 70TB mesh.

“We have many conservationists working around the clock to document the state and properties of each heritage asset,” says Cichy. “Parts of Centre Block are literally being dismantled stone by stone in order to achieve this. Each stone is captured via a sophisticated point cloud scanning process, then digitally reassembled to record the original state for future reference.”

To capture roof geometry, terrestrial scanning wasn’t enough. Because parts of the roof were not easily accessible, a local drone operator was hired to fly around and capture high-quality photos and video of the area, allowing the team to generate detailed photogrammetric meshes from exceptionally high-resolution orthographic photography.
Image courtesy of CENTRUS and John A. Pearson
As the data is collected, it is fed into Unreal Engine, which is used to generate multiple dynamic Level of Detail models (LODs) and visualized using virtual reality walkthroughs. Users can jump to several locations within these models, setting perspective height so they can preview the spaces as if they were there themselves. Several of HOK’s early results have been shared with the client via a variety of tethered (HTC Vive, Oculus Rift, Varjo XR3) and untethered (Oculus Quest and Google Cardboard) VR devices.

“Places like the House of Commons Chamber were created using the photogrammetric mesh,” adds Cichy. “This allows VR users to preview the exact scale, geometry and textures as one would experience within the real House of Commons.”
Image courtesy of CENTRUS and Attilio Pusterla

Real-time design

So far, the HOK team have used Unreal Engine throughout the entire schematic design process for the project, which includes the Centre Block building receiving a host of upgrades including seismic base isolation pads, high-performance insulation, and mechanical and electrical equipment such as enhanced audio devices in the Senate and House of Commons.

“From day one, it’s helped us to perform content audits internally, and convey our proposed design intent in a far more engaging way,” Cichy says. “We do not possess another tool that can handle multi-terabyte data streams as well as Unreal Engine—regardless of whether these are represented in real time or simply harvested to coordinate various data sources.”

Their interactive walkthroughs have already brought huge benefits to the Centre Block project, as clients could make decisions and comment on what they did or didn’t like about the project’s renovation design strategies directly in virtual reality, before spending billions on a decision that could make permanent changes to a site of historic significance.
Image courtesy of CENTRUS
“The greatest benefit in deploying real-time solutions is that they are real time! We do not have to pre-render content and wait hours for it to appear,” Cichy continues, explaining the team were also able to take advantage of Pixel Streaming to have the added flexibility of virtual reality sessions outside of the Unreal Engine platform.

“I personally equate the convenience and impact of this to the massive shift that occurred in the architecture, engineering, and construction (AEC) industry when we transitioned from two to three-dimensional digital processes,” he adds. “If you can conceive a design strategy, it appears. It’s that simple.”
Image courtesy of CENTRUS

Seeing the future in VR

Over the next decade, the HOK team’s goal is to use architectural visualization technologies to document a multitude of future restorative states for this project. This will enable client partners to walk through the virtual Centre Block building to experience and assess future design stages and strategies, including the pre-demolition, post-demolition, and pre-occupancy phases of the project.

“For example, we were recently asked to develop a series of montages that would encapsulate the future state of various high-heritage spaces within Centre Block,” says Cichy, adding that the process of coordinating capture, mesh optimization and development is non-linear, so certain rooms and spaces are being generated on a more aggressive schedule.

Unreal Engine helped the HOK team assess the geometric state of each space, isolate various mesh elements, and generate consensus on both the workload and how each end-state design would be presented to the client.

HOK was also able to take advantage of the expanding AEC ecosystem based on Unreal Engine solutions, such as using 3D Repo to support enterprise-level visual communication and Cintoo for managing point cloud data. Both solutions have developed Unreal Engine integrations to help bring new methods of accelerating decision making.

The HOK team is currently also working on an XR platform that will layer design strategies directly on top of existing spaces within the real Centre Block. This interactive experience will facilitate the layering of design, historical retrograde, and service upgrades on top of existing spaces within the building itself.

According to Cichy, it’s highly likely the experience will be merged with Centre Block’s eventual digital twin, as it will include a comprehensive account of several past states of the project. This is one of the key advantages of adopting real-time solutions—once you have the content in the real-time engine, you can create additional decision-making tools, like a digital twin, without starting from scratch.

“Very rarely is one gifted with the opportunity to work on a project of this magnitude,” Cichy concludes. “Working on a renovation that merges historical context with modern construction techniques is truly unique, and the integration of technologies that are truly at the edge of innovation make this project a once-in-a-lifetime opportunity.”
Image courtesy of CENTRUS
HOK will also be participating in Build: Architecture 2021, a free, two-hour event scheduled for November 2, that will highlight some of the most innovative ways real time is being used today. To register now, please visit:

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