TAA is a crucial tool for developers - but is the impact to image quality too great?
The principles are remarkably straightforward.
8x SSAA on a 1080p screen effectively rendered internally at 8K (!
), while 4x SSAA downscaled from 4K instead.
It’s the brute force method, delivering a stable image with little sub-pixel break-up and pristine edges.
However, the brute force approach means that a tremendous amount of GPU resources are required.
UsingCrysis 3on an RTX 3070, native 1080p runs at nearly 200 frames per second without it being CPU-limited.
However, 4x SSAA takes that down to 70fps, reducing to just 19fps at 8x SSAA.
MSAA, or multi-sample anti-aliasing.
you could think of MSAA as similar to SSAA with one profound difference: only geometry is super-sampled.
However, over time, MSAA disappeared and only a sparing few titles use it today.
There are several reasons for this.
The first is due to deferred rendering, a technique that increases rendering complexity in a highly performant way.
Effects like volumetric lighting and screen-space ambient occlusion (SSAO) also didn’t play nicely with MSAA.
Going back to Crysis 3, edge-smoothing was still present but specular aliasing (the shiny bits!)
were not addressed - it looked poor.
And it’s here where we see the beginnings of TAA.
This impressive super sampling property of TAA was quickly exploited by developers, sometimes to improve performance.
InDeus Ex: Mankind Divided, for example, just three percent of frame-time is occupied with TAA calculations.
TAA resolves softened imagery.
A key issue with TAA is that it resolves softened images.
Part of this is just the nature of what anti-aliasing is.
Even SSAA has a softening factor, technically.
However, if you’re closer, softness is amplified and becomes more obvious.
That softness then becomes even more obvious if the screen resolution is lower.
Another aspect of TAA is that it is frame-rate dependent.
Even the apex of TAA - Nvidia’s DLSS - can have this issue.
So, is TAA a blessing or a curse?
This is critical as a huge amount of users play games at 1080p based on the Steam hardware survey.
The last reason why TAA should be able to be toggled off is due to future scaling.
In the short term, however, TAA is here to stay.
