Quality assessment of 360 video view sessions

Introduced SSIM360 and 360QVM, new quality assessment standards for 360 video streaming. SSIM360 addresses the warping problem by weighting per-sample SSIM scores based on stretching in the equirectangular representation, making it computationally efficient and more accurate than conventional SSIM. 360QVM addresses the field-of-view problem by mapping view direction to pixel density and then to a scaling factor applied to the SSIM360 score, allowing for view-dependent optimizations and more accurate quality assessment of streaming sessions.