![]() ![]() Rather than being an always-on system like ATW, IR was automatically toggled on and off by the compositor. Interleaved Reprojectionīefore the addition of Asynchronous Reprojection to SteamVR, Valve’s platform had Interleaved Reprojection (IR). The feature originally only supported NVIDIA GPUs, but in April 2017 support for AMD GPUs was added. In October 2016, Valve added a similar feature to SteamVR, which they call Asynchronous Reprojection. The feature’s reliance on hardware features addded in recent GPUs was one of the reasons the Rift doesn’t support GeForce 7-series cards or AMD cards predating the R9 series. ![]() It was not available on PC however until the Rift consumer launch in March 2016. The synthetic frame is ready before it’s known whether or not the real frame will finish rendering on time.ĪTW was first shipped on Gear VR Innovator Edition back in late 2014. It is called “asynchronous” because it occurs in parallel to rendering rather than after it. If the current frame doesn’t finish rendering in time, ATW reprojects the previous frame with the latest tracking data instead. Asynchronous Timewarp (ATW)Īsynchronous Timewarp takes the same concept of geometric warping and uses it to compensate for dropped frames. So contrary to common belief, even when you’re hitting full framerate you’re still seeing reprojected frames. The concept of Timewarp is used today by all major VR platforms. Since this takes a fraction of the time that re-rendering would and the frame is sent to the headset immediately after, the perceived latency is lower since the result is closer to what you should be seeing. That is, it warps the image geometrically in the direction you rotated your head between the time the frame started and finished rendering. Timewarp reprojects an already rendered frame just before sending it to the headset to account for the change in head rotation. Timewarp is one of the multiple software techniques Oculus used to get latency low enough to not be noticeable. VR before the Oculus DK1 had much higher latency than today- mostly due to software rather than hardware. It was made to lower the perceived latency of VR. Standard Timewarp in itself did not actually help with framerate, nor was it intended to. ![]() Carmack first wrote about the idea in early 2013, before even the Oculus DK1 had shipped. The idea of Timewarp has been around in VR research for decades, but the specific feature was added to the Oculus software in April 2014 by John Carmack. You may have heard these terms or seen them in the settings of your VR headset, but what do they do, and what’s the difference? Timewarp TimeWarp, Spacewarp, Reprojection, Motion Smoothing. ![]()
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