Facebook's Oculus VR unit has acquired Surreal Vision, a company best known for creating a program which virtually projected Facebook's website onto a wall inside an Oculus Rift virtual reality headset. No sale price was disclosed but the company had four employees, according to LinkedIn.

It's an interesting purchase by Oculus, which itself was acquired by Facebook for $2 billion last summer. Current Oculus Rift development kits do not come with built-in cameras and Oculus software is meant to be immersive. Virtual reality is different from augmented reality, which overlays digital additions onto the world you would see otherwise. Surreal Vision's technology centers around mapping indoor rooms for augmented reality. 

For example, Surreal Vision's founder, Renato Salas-Moreno, used a set of cameras to map a room, and then wrote software that interacted with the room's flat surfaces. So inside the Oculus headset, an actual wall became a Facebook wall, or, users could change their own carpet digitally. 

The purchase could signal increased interest from Oculus in augmented reality. Last December, Oculus bought 13th Lab, an augmented reality company which worked on a similar problem as Surreal Vision, creating 3D maps from photographs. 

Augmented reality and virtual reality are increasingly being developed by the same scientists and companies, and augmented reality in particular is hot. Microsoft's HoloLens is an example of an augmented reality headset, which overlays digital features on the world around the user. Google is making a tablet, Project Tango, with the type of cameras needed for augmented reality applications. 

"At Surreal Vision, we are overhauling state-of-the-art 3D scene reconstruction algorithms to provide a rich, up-to-date model of everything in the environment including people and their interactions with each other," the company said in a statement

Ultimately Oculus' purchase of Surreal Vision looks like a talent grab: Surreal Vision's employees were all experts in the hot field of computer vision, and they'll be moving to Oculus' research center in Redmond, Washington -- not too far from where Microsoft is working on HoloLens.