To get to the settings for graphic detail, from the clipboard menu click Options->Graphic Detail. The Object Detail slider is used to adjust the graphics so that you may have either more object detail and/or better performance from your video card.
Ground Detail Range is the range at which detail terrain objects come into view.
Gamma is used to adjust the overall lighting displayed by your monitor.
Checkbox OptionsDisable other plane skins is used to disable seeing other plane skins. Use this if you are constrained on memory in your computer (i.e. less than 512MB of RAM, for example).
Animated Water is used to enable water animations (i.e. simulated waves). You may not have this option available if your video card cannot support shaders. One some cards this option can cause a large hit in video performance.
Horizon is used to show futher distances into the horizon or to cut the view a bit shorter. Disabled, it may help provide slightly better video performance for some video cards.
Terrain Mipmapping is a technique used to smooth the appearance of the terrain and various transitions. Disabling this option may help to provide slightly better video performance for some video cards.
Optimize Objects is a settings which can help improve the overall performance of the game, but at the expense of using more computer system RAM. If you have plenty of free RAM available, this option would be useful. NOTE: For video cards which lack hardware 3D rendering, this option will not be available.
Disable Weapon Effects will cause weapon effects, such as explosions, smoke, and other visual cues to not display. If your frame rate is taking a severe hit when these effects are played, you can disable them to help retain performance.
Disable Vehicle Effects is much like the weapon effects. Disabling dust trails, smoke, and other effects which are not required for balanced game play. Disable these if you find you are suffering low frame rates when they occur.
Transitions are used by the terrain. Disabling this option will cause the terrain to appear with fix edges between the different types of terrain cells. This may improve the performance of the game when disabled.
Optimize Terrain works much like the optimize objects option. If you have plenty of free RAM and a hardware accelerated video card, this option can provide better option. If your computer is short on RAM, this option can hurt your performance.