NVIDIA TXAA Brings Movie CGI Rendering To PC Games

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Nvidia's Kepler packs a number of efficiency and performance improvements, but one of the GPU's major features has been locked away until now. When the company launched their new GPU core earlier this year, Nvidia debuted a new type of anti-aliasing it dubbed TXAA. Unlike other types of AA, which can often be forced on in the driver and applied to any game, TXAA required specific application support. Funcom's new MMO, The Secret World, was patched last week to add TXAA and we took the game out for a spin to see what it looks like.

What is TXAA?



Click to embiggen

Nvidia is still keeping most of the details of TXAA under wraps, but GeForce.com offers this explanation:
TXAA is a combination of hardware anti-aliasing, a custom anti-aliasing resolve, and a temporal filter. To filter pixels, TXAA uses a contribution of samples both inside and outside of the pixel in conjunction with samples from prior frames, to offer the highest quality filtering possible. In motion, TXAA approaches the quality of other high end, professional anti-aliasing algorithms, though the higher quality filtering used by TXAA does result in a softer image compared to the lower quality filtering of traditional MSAA.
Despite their similar names, TXAA is not a form of FXAA (AMD calls its version MLAA). Fast approXimate Anti-Aliasing creates an pseudo-anti-aliasing effect by applying a post-processing edge-detection filter that blurs line edges. Intel invented and developed early iterations of what it referred to as morphological anti-aliasing, and Nvidia has improved on these early efforts, but FXAA isn't a true form of anti-aliasing.

The "temporal filter Nvidia refers to is a different way of achieving the goals of standard spatial anti-aliasing.TXAA starts with an MSAA implementation, but then averages edge values across multiple frames rather than blowing them up to ultra-high resolutions. That's why Nvidia states that the technology looks better in motion -- static screenshots can't accurately capture the blending that occurs when a character is on the move.

The only anti-aliasing modes available in The Secret World are FXAA (in regular and high quality flavors) and 2x/4x TXAA. It's possible to force certain anti-aliasing methods through the use of Nvidia Inspector, but we stuck to the basic options available in-game. Because the performance hit from enabling FXAA is virtually nil, we skipped testing the standard mode and went straight to HQ. Screenshots below illustrate the three settings.

   
No AA on the far left, FXAA HQ in the middle, and 4x TXAA on the right. Click to enlarge.

Key jagged spots and areas of interest in this first set of images include:
  • The bike
  • The poster hanging above it
  • The red car in the middle-right of the image
FXAA improves some of these areas more than others. The red car is noticeably smoother, but the bicycle doesn't improve much. Bike spokes are worst-case scenario; thin diagonal lines are difficult to anti-alias effectively. The one major problem that FXAA doesn't address -- we'll show you this momentarily -- is texture flickering when the character is moving.

4x TXAA significantly improves the scene with only a modest frame rate hit. Here's the bicycle in all three modes, at 300% zoom.

   
No AA on the far left, FXAA HQ in the middle, and 4x TXAA on the right. Click to enlarge

TXAA does introduce a bit of blur, but it's less than what you'd see from a 4x supersampling implementation. Nvidia has stated that one of the benefits of TXAA is that it duplicates how Hollywood films use AA in rendered scenes. The Secret World doesn't exactly jump out and scream Inception, but the new anti-aliasing method is designed to produce more realistic images rather than overly sharp digital scenery.

Nvidia recommends evaluating the technology in motion, so hit next to see a video comparison.

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Comments

Comments
Jaybk26 2 years ago

Ok, that's pretty sick. Does anyone know what the entry level video card with this costs?

RTietjens 2 years ago

If you have to ask, you can't afford it.

marco c 2 years ago

Check back tomorrow morning. The answer right now and the answer after tomorrow morning will be different...

CDeeter 2 years ago

Now if that isn't a teaser statement, I don't know what is. lol

Jaybk26 2 years ago

Lol, is this going to be one of the "slick deals?"

CDeeter 2 years ago

Ok it's the next morning, what's the answer? lol

marco c 2 years ago

Here's the answer: http://hothardware.com/Reviews/NVIDIA-GeForce-GTX-660-Ti-Round-Up-MSI-EVGA-Gigabyte-Zotac/

Joel H 2 years ago

While I appreciate the compliment, Marco does a good job handling GPU reviews. He's also got far more equipment on hand than I do and can offer a better sense of how different GPUs compare in any given product. 

I prefer to focus on narrower considerations or features; full-frontal deep dives aren't so much my thing. If there are features or games that you want to see tested, speak up -- you'll find us receptive to such things. :) 

mernerion 2 years ago

looks like its going to cost you but probably give you a run for your money.

CDeeter 2 years ago

It does appear to work very well, hopefully they can enable this for more of their cards.

shadizzle 2 years ago

Thats pretty slick for sure, I am curious to see how upcoming titles look with this and a little refinement.

nicoletoledo 2 years ago

Damn. Thats awsome. Imagine if all games are like that (ofcourse pc games) not like console games can. Drool

Erakith 2 years ago

got a 680 on its way.. can't wait to take advantage of this.

enprim22 2 years ago

It does appear to work very well

kidbest100 2 years ago

Anyone else see the "Tesselated toad" on the Crysis 3 Trailer? I bet it would look even cooler with TXAA ;) ( If it isnt already)

sarah.a180 2 years ago

Nice overview, but I'm afraid that you're mistaken when you claim that FXAA is somehow not "true" anti-aliasing. I would suggest you study up on the mathematics of frequency-space representations and filtering before you try to argue against the engineers at NVIDIA.

Aliasing is a patterning artifact caused by high-frequency signal components interacting with a low-frequency sampling space. Anti-aliasing is *any* technique that filters out these high-frequency artifacts. There is no such thing as perfect anti-aliasing: all real low-pass filters are approximations. (Even if a perfect low-pass filter were possible, you would not want to use it for graphics because its non-locality would cause undesirable ringing artifacts.)

All real anti-aliasing filters involve trade-offs between

* aliasing (failure to remove frequencies above the sampling cutoff),

* ringing (caused by frequency truncation),

* excessive blurring (failure to retain frequencies just below the frequency cutoff), and

* complexity (because compute time is finite)

Supersampling is an approximation. So is the box kernel that is typically used to down-sample from the supersampled representation to the traditional one. Coverage-sampling and z-buffer-only supersampling (MSAA) techniques are, in many ways, a bigger compromise than those of FXAA: traditional MSAA looks terrible if not combined with good texture filtering, which is another anti-aliasing technique. The linear texture projection used in texture filtering are another approximation of true texture transforms, and not that great an approximation. (Anisotropic texture filtering is still a linear interpolation technique.)

FXAA is just a different (and far more sophisticated) approximation to a low-pass filter. Because it is a full-screen technique, it outperforms MSAA in many ways. It has slightly more blurring and doesn't do a good job with temporal aliasing, but it is vastly superior at removing aliasing due to transparency or small features—all at a radically lower cost. Most people should probably be using FXAA instead of MSAA in many games unless they already hit 60 FPS with all the effects they want enabled, especially if you are running in 1080p where the extra blurring is negligible. The only real drawback to FXAA is its poor ability to handle temporal aliasing (thus we have TXAA).

Let's try to put a stop to the false dichotomy that FXAA is "blurring" and MSAA is "true anti-aliasing." It's completely false. If anybody is looking for a good introduction, Jim Blinn's "Dirty Pixels" is a great introduction. (And if you don't know who Jim Blinn is, you probably shouldn't claim to know much about computer graphics.)

Joel H 2 years ago

Sarah, 

A full explanation and comparison of FXAA / SSAA / MSAA was beyond the scope of this article. Nevertheless, I read Intel's original FXAA/MLAA whitepaper, spoke extensively with Timothy Lottes at Nvidia, and consulted additional research materials. FXAA is a different approach to the aliasing problem and it utilizes different GPU resources. It's also an approximation by the literal meaning of the acronym. 

Also? Let's avoid the e-peen. "If you don't know who Jim Blinn is, blah blah blah." That's like claiming you can't possibly understand Ron Paul if you haven't read John Locke. History and context give additional data points, they are not required for accurately processing the difference between various AA methods. 

FXAA/MLAA does no sub-pixel sampling. Later versions of FXAA at NV have attempted to reduce the pixel 'snapping' distraction. The advantage of FXAA is that it's fast and can be run on cards that can't handle standard antialiasing. 

Being able to extend AA capability to mobile devices or handheld gaming that wouldn't otherwise see any antialiasing capability at all is good. I daresay that games designed explicitly for FXAA can take steps to reduce the pixel snapping issues. There's evidence that FXAA works fabulously on a cell-shaded game like Borderlands, for example. 

But if you're a user who hates jaggies -- and I am -- FXAA is a joke. Every AA method is a balance of compute time, end visual quality, and speed. When I can afford to, I opt for 4x sparse grid supersampling, or 8xMSAA with supersampled transparencies. The only way most modern games can handle that is if you use SLI -- which again, I've often done.

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