Third Dimension was founded in 2024 by CEO Tolga Kart and Piotr Sokólski, both veterans of the gaming and autonomous vehicle industries, and had raised $7 million in seed funding from investors including Abstract Ventures, MVP, Soma Capital and Solari Capital. Its technology was originally built to speed up game development, but the founders had also eyed defence and autonomous vehicles. "The team is excited to be able to focus on one problem," Kart said.

The appeal for Rivian is the sim-to-real gap, the mismatch between virtual test environments and actual roads. Traditional simulators built on game engines lean on synthetic data, and Kart said a gap between the virtual and real worlds remains. Third Dimension's approach instead recreates real scenarios, letting engineers move cameras, shift other agents and change lighting or weather. Philbin said Rivian had evaluated many providers before choosing this one.

That matters because Rivian collects driving data from tens of thousands of vehicles whose owners enable external camera sharing, receiving more than 400,000 sequences per day according to Philbin. Combining that real footage with the startup's tooling should let the company test rare edge cases without waiting for them to happen on the road, particularly when validating whether a system is good to ship.

The acquisition also gives Rivian a chance to expand its London AI hub. Meanwhile, its existing "Universal Hands-Free" highway software is due to be joined by the end of the year by a version that handles surface streets and highways without touching the wheel, though the driver must still supervise and be ready to take over. Full autonomy is targeted for robotaxi versions of the R2 SUV, set to appear on the Uber app in 2028.