Microsoft Flight Sim VR: Best UserCfg.opt for Cloud Depth Fix

The UserCfg.opt file contains the raw render flags for both Desktop and VR modes. The secret to fixing clouds lies in the PostProcess and VolumetricClouds bitmasks, which are separate for the VR profile.

File Path & Setup

1. Locate the file: * Microsoft Store:%LocalAppData%\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalCache\UserCfg.opt
   • Steam: %AppData%\Microsoft Flight Simulator\UserCfg.opt
2. Scroll to the bottom: Look for the section titled Video followed by {Settings VR.
3. Mandatory: Set the file to Read-Only after editing, or the game will overwrite your “0” values (Disabled) during the next boot.

Optimized “Clear Skies” Configuration Table

Parameter	Recommended Value	Technical Purpose
Sharpen	0	Disables the internal CAS filter to reduce grain in clouds.
Fringe	0	Removes Chromatic Aberration, which blurs the edges of the FOV.
Dirt	0	Removes “Lens Dust” effects that interfere with cloud clarity.
FilmGrain	0	The Master Fix. Disables the noise filter applied to volumetric textures.
Vignette	0	Prevents the artificial darkening of the sky’s corners.

{Settings VR
    ...
    {PostProcess
        Enabled 1
        EyeAdaptation 1
        ColorGrading 1
        Sharpen 0
        Fringe 0
        LensDistortion 0
        Dirt 0
        Upsampling 0
        SecondaryScaling 1.000000
        Vignette 0
        FilmGrain 0
    }
    {VolumetricClouds
        Enabled 1
        Quality 3
    }
}

HowTo: Engineering Maximum Cloud Clarity

Follow these GameEngineer.net technical steps to eliminate the “Shimmering Cloud” effect:

1. DLSS/FSR vs. Cloud Grain: If you use DLSS or FSR, set Sharpening to 0 in the UserCfg.opt. MSFS applies its own sharpening on top of the upscaler’s sharpening, which creates a “double-pass” noise effect that makes clouds look like moving static.
2. The “Ultra” Cloud Paradox: In the VolumetricClouds section, ensure Quality is set to 3 (Ultra). In MSFS, lower cloud settings use a more aggressive Dithering pattern to save performance, which causes the grain. It is mathematically better to keep Clouds at Ultra and reduce your Terrain LOD to balance the frame time.
3. OpenXR Toolkit Foveated Rendering: Since clouds are the most expensive volumetric render, use OpenXR Toolkit to enable Fixed Foveated Rendering. By setting the outer rings to a lower shading rate, you can keep the clouds in the center of your vision sharp without dropping below 40 FPS.
4. Off-Screen Pre-Caching: In the in-game General Options, set Off-Screen Terrain Pre-Caching to Ultra. This reduces the “stutter” when panning your head across high-density clouds or coastlines.
5. Ray-Marched Refinement: To fix the “blocky” edges of clouds against the sun, ensure Bloom is set to On in your config. This “bleeds” the light slightly over the cloud edge, masking the low-resolution nature of the volume map.

Technical Explanation: Volumetric Ray-Marching

MSFS uses Volumetric Ray-Marching to render clouds. Each cloud is a 3D texture sampled along a ray from the camera. To save performance, the engine doesn’t sample every pixel; it uses Temporal Re-projection and Dithering.

The “Grain” occurs when the Dither Pattern ($D_{pat}$) doesn’t align with the Film Grain ($G_{film}$) post-process filter. By setting FilmGrain 0 and Sharpen 0, you remove the high-frequency noise that the engine mistakenly applies to the smooth gradients of the cloud’s density map. This allows the temporal anti-aliasing (TAA/DLSS) to accurately “smooth” the clouds over multiple frames without noise interference, resulting in the “Cloud Depth Fix.”