As far as we can tell, and as far as Acer would say, the company’s mixed reality HMD is actually just a VR HMD with inside-out tracking.
We’ve been clamoring for more information (any solid information, really) on Acer’s upcoming mixed reality HMD specifically, and any of the other supposedly upcoming XR HMDs from other PC makers generally, but so far any details have been sparse. We learned a bit about the Acer HMD at GDC, but…not much. At Acer’s NYC event, we learned a little more. And it was a mixed bag.
It’s Tethered, But Does Inside-Out Tracking
First and foremost, we can confirm that this device is tethered. In this case, that means it does not have its own onboard CPU, GPU, RAM, and storage. Instead, it connects to a PC via a combo HDMI/USB cable. (That PC will need at least the baseline specs detailed here.) It does, however, provide inside-out, 6DoF tracking.
The fact that it’s tethered pops the bubble of hope that Microsoft and its partners figured out a way to build “HoloLens lite” XR HMDs. Instead, it’s more like a cheaper version of the Vive and Rift. (This was not unexpected, but given the name of the device, we had hoped for the former.)
However, the presence of inside-out tracking is a big deal and in a way puts these commodity-level HMDs (or at least, this one in particular) a step above the Vive and Rift, which rely on outside-in tracking for room scale movement.
Inside-out tracking is one of the next holy grail features that the industry needs on VR HMDs. At its best, it provides a world-scale XR experience, like the HoloLens. But it’s also a step up from the outside-in tracking that the Vive and Rift require to achieve room scale tracking. With outside-in tracking, mounted sensors have to be able to “see” the headset. If you move your head in such a way that the sensors lose track of the headset, the immersion is cracked.
An HMD with inside-out tracking, by contrast, moves with you (the HMD wearer).
“Essentially” HoloLens Inside-Out Tracking
How does the Acer HMD accomplish its inside-out tracking? It uses “essentially” the same tracking as the HoloLens. (“Essentially” is the word a rep used to describe it.)
We’re going to have to connect some dots here, but we can start with a few things we know. First of all, we know how HoloLens does its inside-out tracking (scroll to the “Sensors Sensing Sensibly” section, and yes, we still like that subhead).
For those who don’t feel like clicking that link, here’s the section:
The sensor bar on the HoloLens comprises four “environment understanding cameras,” two on each side; a depth camera; an ambient light sensor; and a 2MP photo/HD video camera. Some of these are off-the-shelf parts, whereas Microsoft custom-built others.
The environmental sensing cameras provide the basis for head tracking, and the (custom) time of flight (ToF) depth camera serves two roles: It helps with hand tracking, and it also performs surface reconstruction, which is key to being able to place holograms on physical objects. (This is not a novel approach–it’s precisely what Intel is doing with its RealSense 400-series camera on Project Alloy.)
These sensors work in concert with the optics module (described above) and the IMU, which is mounted on the holographic lenses, right above the bridge of your nose.
Said the presenter, “Environment cameras provide you with a fixed location in space and pose,” and the IMU is working fast, “so as you move your head around…you need to be able to feed your latest pose information into the display as quickly as possible.” He said that HoloLens can do all of this in
Source: Tom’s Hardware