A Wider Window Into the Virtual World
Valve’s Index headset features two LCDs with a per eye resolution of 1440 x 1600 (Valve has not disclosed the size of the panels). That's the same resolution as the HTC Vive Pro and Samsung’s Odyssey (Plus) headsets. However, you get a more full FOV with the Index.
Valve designed custom dual-element lenses for the Index. It said that these lenses provide “high geometric stability” and “minimal shape distortion,” which enables Valve to “maximize FOV without sacrificing edge-to-edge clarity.” In other words, the Index can make use of more of its display than older headsets.
Valve also installed the displays in the Index at a 5-degree outward cant to maximize the peripheral view. The company said that the difference in FOV between the Index and Vive could be as significant as 20 degrees for typical users.
I have a 6mm VR Cover installed on my Vive, which improves the FOV, so the difference wasn’t as pronounced as it could have been from my perspective. But the Index still offers a broader view of the virtual world than the Vive. Pimax headsets, like the Pimax 5K Plus, Pimax 8K Plus and Pimax 8K X, are your best options for the broadest FOV.
RGB Subpixels Make a Huge Difference
The Index has the same resolution as the Vive Pro and Odyssey, but not the same display technology. Whereas the Vive Pro and the Odyssey feature AMOLED displays, which produce excellent contrast and deep blacks, the Index features ultra-low persistence LCDs. While it’s true that the LCD panels can’t produce true blacks because they require backlighting to function, LCD panels can take advantage of RGB subpixel arrays that improve image sharpness and eliminate screen door effect.
Valve claimed that the RGB LCDs provide “50% more subpixels than OLED” displays, which results in “three times better” fill-factor, and I’m inclined to agree. The image clarity in the Index headset is second only to HP’s 4K per eye Reverb headset. I would say it provides better image clarity than my Pimax 5K Plus.
80 Hz, 90 Hz, 120 Hz, or 144 Hz? The Choice Is Your GPU’s!
The LCD panels in the Index also provide another distinct advantage over OLED panels: They’re available with higher refresh rates. Valve’s Index is the first PC-VR headset to offer panels that support 120 Hz and even 144 Hz operation, although the latter is an experimental feature.
The SteamVR software enables you to select 80 Hz, 90 Hz, 120 Hz or 144 Hz, which allows the device to scale with your computer. If your PC isn’t quite up to par for the higher refresh rates, you can dial the settings back until your next system upgrade. To be honest, you’ll likely need to keep the settings dialed back for a while. 90 Hz is already a pretty tall order for most graphics cards in many games. You will need a top-tier GPU to run your Index at 120 Hz or higher, as our benchmark results illustrate.
Ready for the Future
Valve is so serious about making the Index a premium device that it even planned for future expansion and advancements. The front faceplate of the Index headset features a removable panel that covers a cavity that Valve calls the “Frunk.” Valve doesn’t have any specific plans for the front compartment but put a USB port there so that developers and hardware makers can experiment with it. Some have assumed the Frunk would fit a Leap Motion controller. You can slip one in the slot, but there’s not enough room for the USB cable, so it doesn’t quite fit.
Valve also installed a pair of front-facing, global-shutter RGB cameras on the Index. Currently, the cameras don’t have a specific use, but Valve said they were designed for computer vision and they're looking forward to computer vision experts to make use of them. At the very least, we hope to see the adoption of stereo passthrough for augmented reality experiences. Valve said it would have more to share about the cameras later this summer.
As usual, my VR headset test system consists of an Intel Core i7-8700K CPU overclocked to a clock speed of 4.8 GHz, 16GB of G.Skill SniperX DDR4-3600 RAM, a Crucial 500GB MX200 SSD and an Nvidia GeForce RTX 2080 Founders Edition graphics card.
For this evaluation, all tests were conducted with version 441.87 of Nvidia’s Game Ready GeForce driver installed.
We use Nvidia’s FCAT VR tool to capture the real-time frame rate and frame time data from SteamVR. For each variable change, we capture three 60-second tests. I chose to focus my attention on the adjustable refresh rate rather than adjust the display resolution. I set SteamVR’s rendering scale to 100%, which resulted in 2016 x 2240 pixels per eye.
I focused on 90 Hz, 120 Hz and 144 Hz. I ignored the 80 Hz mode because the RTX 2080 had no trouble with 90 Hz, so reducing the frequency served no purpose. I also ran tests with motion smoothing enabled and disabled to see what effect it has on performance—both objectively and subjectively.
We don’t often use Elite Dangerous for our VR tests, but we brought it into the mix because it’s the best way we could think of to evaluate how well the LCD panels handle dark environments. It’s also a very demanding game, so it makes a good benchmark test.
Elite Dangerous was not originally designed for VR, and as such, playing this game in VR puts your PC to the test. Frontier Developments created VR graphics pre-sets, which were optimized for the original Vive headset. We set the game to VR medium for our Index tests because VR high was too much for our i7-8700K and RTX 2080 combo—even at 80Hz.
Project Cars 2
Project Cars 2 is the game where we noticed the biggest difference between refresh rates. At 80Hz, our system had no problem delivering the necessary frame rate to keep things moving smoothly, and we experienced no missed frames.
It wasn’t until we bumped the refresh rate to 90 Hz that we noticed that 80 Hz was holding us back. System performance wasn’t a problem, but our driving performance was affected. Flipping back and forth from 80 Hz to 90 Hz yielded the same results. Our lap time was consistently slower, with the lower refresh rate enabled.
Moving up to 120 Hz didn’t give us the same positive results. Our system struggled to achieve a higher frame rate than 90 Hz, which resulted in more than 10% missed frames. Despite achieving a similar average frame rate, the 120 Hz refresh rate negatively impacted our lap time performance.
Since our system struggled at 120 Hz here, we didn’t run Project Cars 2 at 144 Hz.
We were surprised to learn that higher refresh rates help in Beat Saber, too. The higher we set the refresh rate, the easier it became to prepare for each swing. The boxes come at you so fast that we wouldn’t have guessed that it would make a difference, but it did.
The faster the refresh, the smoother the animation appeared, and that somehow translated to faster calculation of when to swing and which arm to swing. It felt like time slowed down, and our score improved as a result.
We didn’t notice any improvements to our abilities in Doom VFR using the Index headset.
We couldn’t tell the difference between the varying refresh rates in this game until we cranked up the resolution. At that point, the performance hit affected the frame rate such that the game became more difficult and less comfortable to play.
I would probably sacrifice that higher refresh rate for more frames per second for Doom VFR. That said, if your GPU can handle it, you’ll benefit from less motion blur when running the game at 120 Hz or more.
Boneworks is one of the first VR titles designed for the Index controllers, and this is the first time we’ve used it as a benchmark test. It incorporates the finger tracking and pressure sensing features of the Index controllers to enable fancy hand interactions that aren’t possible with other VR controllers. To get the ultimate experience out of this game, you need a pair of Index controllers.
We were surprised to see how well the performance scaled to higher refresh rates. We ran our tests with 2x MSAA, but it appears we could have justified at least 4x on our system.
We didn’t notice a significant difference in gameplay between the varying refresh rates. 144 Hz felt somewhat smoother than 80 Hz, but wasn’t a groundbreaking change.Strive for the highest refresh rate your GPU can manage, but you’re really not missing much if you can’t go beyond 90 Hz.
Valve didn’t initially plan to make its own VR headset but developed the class-leading Lighthouse tracking technology, made licenses available for free and worked with HTC, which licensed both generations of Valve’s tracking system. However, HTC appears to be moving away from Valve’s base station-based tracking solution in favor of inside-out tracking (no base stations required), as found on the HTC Vive Cosmos and HTC Vive Focus Plus.
Valve developed the Index headset in-house, and, as a result, it was able to control every aspect of its design, allowing for several innovative design choices that will surely inspire headset design for years to come.
If there's a better VR headset for consumers, I haven't tried it yet. There is certainly room for improvement with the Index—most notably, I would like to see it go on a diet. If you have money to burn, and you want the best home VR experience that money can buy, the Index headset combined with the controllers delivers a champion-level consumer VR experience.
MORE: Virtual Reality Basics