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Exploring Relativty

Recently I came across the Relativty VR headset and was very intrigued by their homebrewed version of a virtual reality HMD (head-mounted display). The VR industry is ruled by Facebook, Valve, and HTC, with Facebook owning over 50% of the market while having virtually no competition in the 300-400$ price range. It feels like Relativty is trying to help offer an alternative to those who want to avoid the Facebook ecosystem without breaking the bank. However, to get a Relativty HMD, you have to build it yourself and have an inferior product compared to the $300 Oculus Quest 2. Still, for tinkers and those who consider giving Facebook more data a death sentence, it’s hard to find a better alternative. Although to truly beat Oculus, you have to make some modifications.

Image of The Relativity HMD (from https://www.relativty.com)

The good news is that every shortcoming of the Relativty HMD can be overcome, unlike Quest 2 with its Facebook controlled ecosystem. The first issue with Relativty HMD is the tracking; right now, Relativty uses a webcam and Nvidia’s GPU Cuda cores to track the user in 6 degrees of freedom. While technologically impressive, this method leads to more stress on the GPU (this is not ideal for VR since overloading the GPU can lead to severe motion sickness). It also causes inaccurate tracking as you are relying on a single low-resolution webcam and primitive AI to track the HMD. Ideally, a HMD would have sub-1-millimeter precision tracking and under 20 milliseconds of total latency. Also, the Relativty HMD has no controllers, limiting its use to mostly racing games and 360 degree video. These two issues, I believe, can be fixed using some of the fantastic tools from Valve.

First off, Valve is an industry leader in terms of tracking precision with its SteamVR tracking system, which uses a series of IR emitters and two wall-mounted sensors (known as base stations) to track any object in 3d space. Using a Vive puck combined with two Base Stations, you can modify the Relativty HMD to be tracked through SteamVR. However, it’s not as simple as buying a puck and two Base Stations; you have to fiddle with Valve’s OpenVR API to link the puck’s tracking to the Headset’s 3-dimensional position. After that, the HMD should have 6 degrees of tracking capability. SteamVR can also fix the lack of controller input. Valve’s Index controllers are the best controllers out on the market with their finger tracking and excellent ergonomics. They are also SteamVR compatible, so you can effectively kill two birds with one stone by using SteamVR to track the HMD and the controllers at the same time. 

SteamVR Base Station 1.0
Valve's $279 Index controllers
Vive Tracker (commonly referred to as the puck)

However, the addition of SteamVR tracking brings up new issues in terms of cabling and cost. VR is very immersive when it works well, but when you trip on or feel the tug of a cable, it kills your immersion. The Relativty HMD, unfortunately, needs lots of cables as it uses lots of off the shelf components that aren’t purpose-built for VR. To use the Headset, you need a display port and two micro USB cables; for reference, the Quest 2 uses a single USB Type-C cable (or wireless streaming), and the Rift S uses a proprietary cable that splits into two connectors. At least you can rely on Bluetooth headphones for the Relativty HMD, so you won’t have a headphone cable adding to the mess. But the real issue is the cost, as adding SteamVR tracking and high-end controllers to a homebrew Headset, while cool (and an excellent thing to brag about to friends, family, and the weird guy you met at Arby’s last week), does not make much financial sense. Overall this will cost you more than the 600$ HP Reverb G2, which has far better displays and more convenient inside-out tracking. And the total package will be slightly less expensive than the 1000$ Valve Index, which already comes with the controllers, better external sensors, and a better HMD.

The Oculus Quest 2 is the best choice for anyone wanting to get into VR without breaking the bank.

So what’s the point? The point is if you want to get into VR, you should get a Quest 2 ($300), Reverb G2 ($600 + good gaming pc), or a Valve Index ($1000 + a good gaming pc). But for those that want the pride associated with doing something on their own while getting to experience VR, Relativty is the perfect place to start. Even though I own a Quest 2 and Rift CV1, I personally cannot wait to get started building my Relativty HMD, and I will be posting detailed updates for those curious and those who wish to follow me every step of the way.