Modding-OpenMW.com

To enable shadows via OpenMW-Launcher:

• Click the Graphics icon at the top of the launcher
• Click the Shadows tab
• Check the box next to Enable Player Shadows
• Check the box next to Enable Actor Shadows
• Check the box next to Enable Object Shadows
• Check the box next to Enable Terrain Shadows
• Note that not all shadows settings are exposed via the launcher

Near Perfect Shadow Settings Pre-Set (3-5 FPS cost in testing on modern hardware)

number of shadow maps = 3
split point uniform logarithmic ratio =0.8 
compute tight scene bounds = true
shadow map resolution = 4096
normal offset distance = 8.0

In general you can use the above settings in pretty much any setup with some slight tweaks.

Adding maximum shadow map distance to your settings file, and setting the value to 4096, which is half the regular default of 8192, will improve your FPS.

Getting rid of compute tight scene bounds or lowering your number of shadow maps will increase your FPS if you need it. You should start with getting rid of compute tight scene bounds.

If you are in need of VRAM, you may lower your shadow map resolution to either 2048 or 1024.

If you are struggling for FPS, it is quite possible that not using shadows at all could be an option rather then having subpar looking shadows.

On 0.49 Dev Builds, increasing number of shadow maps will only cost you a bit of FPS, and will not cause you any texture issues. Highly suggest that you try out 4 shadow maps (or more) if your CPU can handle it, the extra map is helpful visually.

Please see the Tips: Performance page for more information about shadows performance tweaking and testing, as well as the official documentation for shadows for more information about related settings.