Nvidia's DLSS Technology Analyzed: It All Starts With Upscaling

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Analysis of the Rendering Pipeline

Really, none of the performance-oriented data is new. We already did quite a bit of testing with DLSS for the GeForce RTX 2080 Ti, 2080, and 2070 reviews, after all. So, it was time to pull out the heavy artillery: Nvidia's Nsight Graphics analyzer. The software is described as "a standalone developer tool that enables you to debug, profile, and export frames built with Direct3D (11, 12, DXR), Vulkan (1.1, NVX Vulkan Raytracing Extension), OpenGL, OpenVR, and the Oculus SDK." In this project, we're using it to break down all of the rendering steps.

Rendering in Final Fantasy XV

There are approximately 50,000 rendering steps in the Final Fantasy XV demo, some of which we illustrate in the following album. But one highlight stands out above the rest: at 4K with DLSS enabled, all of the rendering steps are performed at QHD. It's only the penultimate image that jumps to 4K, right before the menu is overlaid.

Also interesting, when the rendering is finished in QHD, the graphics card applies anti-aliasing just before going into 4K. We don't know the nature of this anti-aliasing step, but we suspect that it's simply TAA for two reasons. First, it's ineffective on the first frame of a new scene, similar to temporal anti-aliasing. Second, DLSS appears to only be compatible with games (or demos for now) that support TAA.

Rendering in Infiltrator

The Infiltrator demo appears to be more complex than Final Fantasy XV, reaching as many as 100,000 rendering steps for some frames. Still, the result is the same: all of the steps are performed at a lower resolution before being output to a higher target resolution at the very end.

At 4K, we again see DLSS operate at QHD behind the scenes. Switching to QHD with DLSS shows the technology working at 1708x960, or exactly two-thirds of the desired resolution.

Given our results, it's clear that DLSS first renders at a lower resolution: 2560 x 1440 for a 4K output and 1708 x 960 for a QHD target. The ratio is always 150% between the base and target.


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Bruno Cormier
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25 Comments Comment from the forums
  • hixbot
    OMG this might be a decent article, but I can't tell because of the autoplay video that hovers over the text makes it impossible to read.
    Reply
  • richardvday
    I keep hearing about the autoplay videos yet i never see them ?
    I come here on my phone and my pc never have this problem. I use chrome what browser does that
    Reply
  • bit_user
    21435394 said:
    Most surprising is that 4K with DLSS enabled runs faster than 4K without any anti-aliasing.
    Thank you! I was waiting for someone to try this. It seems I was vindicated, when I previously claimed that it's upsampling.

    Now, if I could just remember where I read that...
    Reply
  • bit_user
    21435394 said:
    Notice that there is very little difference in GDDR6 usage between the runs with and without DLSS at 4K.
    You only compared vs TAA. Please compare against no AA, both in 2.5k and 4k.
    Reply
  • bit_user
    21435394 said:
    In the Reflections demo, we have to wonder if DLAA is invoking the Turing architecture's Tensor cores to substitute in a higher-quality ground truth image prior to upscaling?
    I understand what you're saying, but it's incorrect to refer to the output of an inference pipeline as "ground truth". A ground truth is only present during training or evaluation.

    Anyway, thanks. Good article!
    Reply
  • redgarl
    So, 4k no AA is better... like I noticed a long time ago. No need for AA at 4k, you are killing performances for no gain. At 2160p you don't see jaggies.
    Reply
  • coolitic
    So... just "smart" upscaling. I'd still rather use no AA, or MSAA/SSAA if applicable.
    Reply
  • bit_user
    21436668 said:
    So, 4k no AA is better... like I noticed a long time ago.
    That's not what I see. Click on the images and look @ full resolution. Jagged lines and texture noise are readily visible.

    21436668 said:
    No need for AA at 4k, you are killing performances for no gain.
    If you read the article, DLSS @ 4k is actually faster than no AA @ 4k.

    21436668 said:
    At 2160p you don't see jaggies.
    Depending on monitor size, response time, and framerate. Monitors with worse response times will have some motion blurring that helps obscure artifacts. And, for any monitor, running at 144 Hz would blur away more of the artifacts than at 45 or 60 Hz.
    Reply
  • Lasselundberg
    i hate your forced video's .....and why is there no 2080ti FE in stock anywhere
    Reply
  • s1mon7
    Using a 4K monitor on a daily basis, aliasing is much less of an issue than seeing low res textures on 4K content. With that in mind, the DLSS samples immediately gave me the uncomfortable feeling of low res rendering. Sure, it is obvious on the license plate screenshot, but it is also apparent on the character on the first screenshot and foliage. They lack detail and have that "blurriness" of "this was not rendered in 4K" that daily users of 4K screens quickly grow to avoid, as it removes the biggest benefit of 4K screens - the crispness and life-like appearance of characters and objects. It's the perceived resolution of things on the screen that is the most important factor there, and DLSS takes that away.


    The way I see it, DLSS does the opposite of what truly matters in 4K after you actually get used to it and its pains, and I would not find it usable outside of really fast paced games where you don't take the time to appreciate the vistas. Those are also the games that aren't usually as demanding in 4K anyway, nor require 4K in the first place.

    This technology is much more useful for low resolutions, where aliasing is the far larger problem, and the textures, where rendered natively, don't deliver the same "wow" effect you expect from 4K anyway, thus turning them down a notch is far less noticeable.
    Reply