FSX: Relief for the Blurries

Blurry ground textures must be near the top of many ’simmers’ complaints about both FS9 and now FSX. I’ve tried tweaking the fiber_frame_time values in the fsx.cfg file, but alotting more thread time for processing textures has a negative performance impact on my aging computer, and the tradeoff wasn’t worth the effect in my opinion. Last night, I stumbled onto an Avsim forum thread that provided me with another way to attack the blurry problem, one that fixed it nicely. Note: this fix is only for nVidia video cards. I’m not sure if or how you could do the same with an ATI, but it might be possible.

Recently, Gary Summons noted that adding the line “MipBias=6″ to your fsx.cfg file would stop the sim from reverting to lower mips for ground textures in the near distance. I tried it, and it’s true. However, the other problem that then resulted on my system was an unacceptable shimmering in the textures. I found it more distracting than the original blurring, and backed out the change. The forum thread I read last night mentioned a companion tweak that makes MipBias viable: in addition to adding that line to your fsx.cfg, alter your video card settings to set “Negative LOD Bias” to clamp, instead of allow. The two fixes, in combination, made a dramatic difference in the sharpness of my FSX world without any noticable performance impact.

To recap, here are the two changes:

1. In your fsx.cfg file, find the [DISPLAY.Device.xxx.0] heading. The “xxx” will be replaced with a reference to your video card. Under that heading, add this line: MipBias=6 (Phil Taylor says users have reported good results with numbers from 5-7, but 6 is a good place to start.) My fsx.cfg display entry now looks like this:

[DISPLAY.Device.NVIDIA GeForce 7600 GS.0]
Mode=1280×1024x32
TriLinear=1
AntiAlias=1
MipBias=6

2. If you use an nVidia video card, go into your video settings. Using the “Advanced Settings” view, find the “Negative LOD Bias” setting, and change it to “Clamp”.

If your results are like mine, the next time you start FSX you’ll be shocked at how sharp and beautiful the ground textures are. And without sacrificing frame rates! Now that’s my idea of a great tweak. Thanks to Gary, Phil, and weeniemcween for the info.

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