Optimal Framebuffer Resolution for VR device

[Bloodwyn]

Dear Vive folks,

today, I noticed that OpenXR recommends different resolutions per eye for rendering to the VIVE Cosmos depending on what OpenXR runtime I use.

Vive OpenXR: 2500x2953

Steam OpenXR: 2584x3052

Native Resolution according to the official specs: 1440 x 1700

I wonder why the runtimes recommend these odd resolutions (2953 is a prime number 😁). Wouldn't the VR experience be better if the images were rendered in the native resolution (FPS wise) or in a muliple of the native resoultion for a higher quality (e.g. 2880x3400)? Shouldn't the recommended resolution be the native resolution of the device, and the maximum a limiting value for developers when trading quality vs. performance?

OpenXR Struct I am talking about: https://registry.khronos.org/OpenXR/specs/1.0/man/html/XrViewConfigurationView.html