Turning on Anisotropic Filtering

For the most part Half Life 2 doesn’t absolutely beg for anisotropic filtering to be enabled, but there are definitely a few situations where image quality could be improved by turning it on. 

Looking at the peach colored metal platform towards the right of the images before you can see some of the benefits of anisotropic filtering in Half Life 2:


Aniso Disabled


8X Aniso Enabled - ATI


8X Aniso Enabled - NVIDIA

So there's definitely an improvement with 8X anisotropic filtering enabled but the difference in image quality between ATI and NVIDIA is tough to quantify. The two look quite similar in our opinion, with ATI getting the nod for slightly better image quality (the difference is quite subtle).

One issue we found in Half Life 2 with anisotropic filtering enabled is that the amount of resulting texture shimmering was borderline unbearable.  The shimmering was worse on NVIDIA cards than on ATI cards, but it was definitely present on both.  Part of the cause of the shimmering was the fact that all modern ATI and NVIDIA cards have resorted to a less ideal method of distance calculation for anisotropic filtering, which contributes to the shimmering issues we noticed under Half Life 2.  With the release of the GeForce 6 series, NVIDIA moved to a method of anisotropic filtering using a weighted manhattan distance calculation, similar to what ATI had been doing for quite a while.  The problem with the weighted manhattan distance calculation is that it is much more sensitive to the orientation of a surface in respect to the viewer, which can cause more of these shimmering issues. 

NVIDIA’s NV3x line used a Euclidean distance calculation that was less sensitive to surface orientation and thus reduced some of the shimmering issues we encountered under Half Life 2. 

There are some levels in Half Life 2 where enabling anisotropic filtering improves image quality, but then there are others where image quality is improved at the expense of increased texture shimmering.  Rest assured that the shimmer occurs on both ATI and NVIDIA cards and it seems that the only way to get around it (unless both ATI and NVIDIA choose to employ different methods of anisotropic filtering) is to leave it disabled if it bothers you enough. 

In terms of anisotropic filtering image quality, we just showed that we were hard pressed to find any image quality differences between ATI and NVIDIA’s solutions under Half Life 2.  In motion however, NVIDIA’s drivers did seem to cause more texture shimmering than ATI’s with anisotropic filtering enabled. 

Turning on Antialiasing Head to Head: ATI Radeon X800 XT vs. NVIDIA GeForce 6800 Ultra
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  • ballero - Wednesday, November 17, 2004 - link

    it'd be nice a comparison between cpu
  • Jalf - Wednesday, November 17, 2004 - link

    To those wanting benchmarks on older hardware, remember that this is a hardware site, not a games review site.

    Their focus is on the hardware, and honestly, few hardware enthusiasts can get excited about an 800 mhz cpu or a Geforce 3. ;)

    For AT, HL2 is a tool to compare new *interesting* hardware. It's not the other way around.
  • CU - Wednesday, November 17, 2004 - link

    I would also like to see slower cpu's and 512meg systems tested. It seems all recent cards can run it fine, so it would be nice to see how other things affect HL2.
  • CU - Wednesday, November 17, 2004 - link

    Based on the 6800nu vs 6600gt I would say that HL2 is being limited by fillrate and not bandwith. I say this since they both have about the same fillrate, but the 6800nu has around 40% more bandwidth than the 6600gt. So, unlocking extra pipes and overclocking the GPU should give the most increase in fps. Anyone want to test this?
  • Jeff7181 - Wednesday, November 17, 2004 - link

    ... in addition... this is a case where minimum frame rates would be very useful to know.
  • Jeff7181 - Wednesday, November 17, 2004 - link

    Those numbers are about what I expected. I'm sorta thinking that triple buffering isn't working with the 66.93 drivers and HL2 because I have vsync enabled, it seems like the frame rate is either 85 or 42.

    I also suspected that anistropic filtering wasn't particularly necessary... I'll have to try it without and see how it looks... although with 4XAA and 8XAF I'm still getting acceptable frame rates.
  • nserra - Wednesday, November 17, 2004 - link

    #8 i never heard of 6800 extra pipes unlocked, where did you see that. Arent you making some confusion with the Ati 9500 cards?
  • MAME - Wednesday, November 17, 2004 - link

    Make some budget video card benchmarks (Ti4200 plus or minus) and possibly a slower cpu or less ram so that people will know if they have to upgrade
  • Akira1224 - Wednesday, November 17, 2004 - link

    #8 Thats not a fair comparison. Yes atm it would seem the 6800Nu is a better buy. However if you go to Gameve you will find the XFX (clocked at PCIe speeds)6600GT for $218. Thats a much better deal than your example using Newegg. You talk about a $5 diff... if you are a smart shopper you can get upwards of a $50 diff.

    THAT makes the 6600GT the better buy. Esp when you consider that the market this card is aimed at is not the same market that will softmod their cards to unlock pipes. Either way you go you will get great performance.

    I digress off topic.... sorry.
  • nserra - Wednesday, November 17, 2004 - link

    You didn’t use overclocked nvidia cards like hardocp did. That Kyle has the shame to say he used stock clock, those BFG OC are overclocked from factory. Just 25Mhz but its something.

    Very good review!!! Better then the NVIDIA's GeForce 6600GT AGP review where something was missing.

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