- All developers actively developing experiences for Google Cardboard should use the open source Cardboard SDKs for iOS, Android NDK, and Unity XR Plugin.
- The Daydream View VR headset is no longer available for purchase as of October 15, 2019. As of November 2023, previously supported devices will no longer be able to download and install Google VR Serivces (Android application ID com.google.vr.vrcore) for new users.
Asynchronous Reprojection
Page Summary
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Asynchronous reprojection maintains high frame rates and smooth motion in VR experiences, even with system load fluctuations, by re-adjusting frames to account for head rotation.
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This technology utilizes the most recent frame to prevent judder, ensuring a consistent user experience even if the application drops frames.
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Asynchronous reprojection is automatically enabled on Daydream platforms and primarily benefits 3DoF VR experiences, correcting for rotational movement.
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While not correcting positional movement in 6DoF, maintaining high frame rates in both 3DoF (60 FPS) and 6DoF (75 FPS) apps is crucial to minimize artifacts and discomfort.
Asynchronous reprojection is a graphics technology that ensures high performance VR rendering, even during times of high system load. It provides consistent and judder-free motion when the user rotates their head.
The 'reprojection' part of asynchronous reprojection works by adjusting the position of the rendered frame just before it is seen by the user to account for rotational user head movement while the frame is being rendered. The 'asynchronous' part means that the technology will always use the most recent rendered frame, ensuring that even if the app drops a frame, the user-visible frame rate does not drop.
Asynchronous reprojection has three major effects:
- It ensures that the frame rate experienced by the user remains high, which is critical to user comfort in VR.
- It reuses frames when the application isn't able to draw.
- It ensures that movement within the app feels smooth and does not judder.
Supported platforms
All Daydream and Daydream Standalone applications have asynchronous reprojection automatically enabled.
Cardboard does not support asynchronous reprojection.
3DoF vs 6DoF
Asynchronous reprojection is designed for 3DoF head movement, as it only corrects for rotational movement.
Asynchronous reprojection does not correct for positional movement in 6DoF apps, which means if the app framerate drops the user will begin to experience a disconnect between the rendered and actual position. The lower the app frame rate, the larger the disconnect. Lower frame rates can also introduce errors associated with animations and other visual effects.
Performance recommendations:
- In 6DoF, apps should target 75 FPS. Drops below 60 FPS will have noticeable artifacts and cause user discomfort.
- In 3DoF, apps should target 60 FPS. Drops below 45 FPS will have noticeable artifacts and cause user discomfort.