The VR thread. U R Not red(e) PSVR2 is legitimate!

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Started by Mmm_fish_tacos, Sep 05, 2015, 06:10 PM

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How sick of Pi's VR hype are you?

the-pi-guy

NeoGAF - View Single Post -  30min PSVR technical presentation (Feb.2016)

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Originally Posted by Joystick
 
 

 
 I understand how reprojection works, but the way that devs explain it is that they take the sensor data at the start of the frame, render, then as late as possible poll the sensors again and reproject for the new orientation. What I haven't seen or heard mentioned is if the engine uses that sensor data as-is or instead estimates the final orientation/position for the future point in time that the image will reach the player's eyes (based on remaining frame time & latency to send to the display), renders for that later estimate, then does the same when estimating final orientation for reprojection. For example, if head rotation is constant it is easy to calculate the orientation in 16ms time, just add the same rotation that occurred during the last frame and render for that. Even acceleration could be taken into account. After all, the polling rate of the sensors and camera is very high (~1000Hz) and even fast head movement is comparatively quite slow so you could calculate speed and acceleration quite well. I'm assuming that this is what is actually being done, right? In which case reprojection is only filling a small gap, especially if natively rendering at 120fps. I'd like to know how many degrees and typical pixels we're talking about.

 
Some degree of prediction is "always on" I think, therefore it is factored in whenever you are rendering or just re-projecting.  As for how many pixels we are talking about, you can get n idea by looking at the re-projection artifacts in this direct feed video from The London Heist. https://www.youtube.com/watch?v=m2CXbjwLv2w Pay very close attention to the top corners when view turns around. Especially the top/left one. It's *very* hard to notice in motion (they seem to be hiding it with some sort of edge mirroring so you don't see black areas popping in) but here are a few frames I've captured that clearly show the artifacts.
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Reminds me of the old PS1 games :D Anyway... It is worth noting this is a 1+ year old footage. Stuff might have changed since then. Finally, here is a good video showing re-projection in action on the Rift with VorpX https://youtu.be/12R8Z4mssoY?t=12m43s