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Leadtek Ti4400 GeForce4 Review
By: Typedef Enum - April 15, 2001

Anisotropic filtering/4xs

The next topic I would like to cover centers on anisotropic filtering and Antialiasing. In particular, I want to provide some insight into this feature and the new 4xs Antialiasing mode. Without getting into extreme details, this new mode is a hybrid between 4-sample MultiSampling Antialiasing, and traditional SuperSampling. The key thing to recognize is the fact that this mode shouldn't require the same level of anisotropic filtering as the traditional MSAA modes, due to the nature of Super Sampling.

You might recall several months ago, I did an analysis of the GeForce3 and ATI 8500 Antialiasing modes, and determined that MSAA required somewhere between 2x and 4x anisotropic filtering to match the quality of a Super-Sampled output. This is similar to what I wanted to determine, with regards to the Leadtek GeForce4 board.

What I have basically done is taken several screenshots of NOLF using all possible combinations of anisotropic filtering, and 4xs Antialiasing. The goal? To determine what level of anisotropic filtering is necessary in order to be on-par with a non-FSAA screenshot with 8x anisotropic filtering. Let's look at the results.

First up is the reference screenshot.


No FSAA, 0x AF

Notice the ugly jaggies? As expected, the floor textures get pretty fuzzy as the depth increases.

Now, let's take a look at the same shot with 8x Anisotropic filtering.

No FSAA
8x AF

Now that's more like it. The textures on the floor of the scene look nice and crisp. However, those jaggies are ridiculous!

Let's take a look at 4 screenshots all taken using the 4xs Antialiasing mode, with varying levels of Anisotropic filtering. We'll see if we can draw some conclusions from these screenshots.

4xs 4xs 4xs 4xs
0x AF 2x AF 4x AF 8x AF
  • When using 4xs Antialiasing, you get "some degree" of Anisotropic filtering out-of-the-bag.
  • You can achieve 8x-like Anisotropic filtering in 4xs by enabling somewhere between 2x and 4x.
  • Jaggies are ugly, and you would be crazy not to enable this feature should you purchase this board!

To justify this position, let's take a look at the following 6 images.

Shot 1 Shot 2 Shot 3 Shot 4 Shot 5 Shot 6
No FSAA No FSAA 4xs 4xs 4xs 4xs
0x AF 8x AF 0x AF 2x AF 4x AF 8x AF

Let's quickly talk about each shot, from left to right.

  • Shot 1: Without Anisotropic filtering, you have a blurry mess.
  • Shot 2: Raising the Anisotropic filtering addresses the blurry issue entirely.
  • Shot 3: 4xs, all by itself, lessens the blurry issue.
  • Shot 4: 4xs with 2x AF is extremely close to Shot 2.
  • Shot 5: 4xs with 4x AF is definitely on-par with Shot 2.
  • Shot 6: 4xs with 8x AF: I'll be darned if I can't distinguish this one from Shot 5.

I have gone back and forth many times over, scrutinizing these screenshots. Personally, I would strongly recommend simply using 2x, since it will preserve a little bit more performance.

You be the judge. If you bought this card, and wanted to use 4xs with Anisotropic filtering, would you really need to force, say, 8x Anisotropic filtering?

Summary

When you see the 4xs performance numbers, bear in mind that you won't have to absorb the additional performance hit that's associated with high levels of anisotropic filtering. Although the 4xs mode will bring about a larger performance hit than, say, 4x Antialiasing, you also will not have to force such a high level of filtering as well. Plus, you will also get a much better quality AA image than the standard 4x mode.

Next Page: More 4xs Antialiasing

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Last Updated on April 15, 2002

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