Determines the screen resolution in which the DirectRT session will be run. The essential trade off is that text and graphics look better under higher resolutions (e.g., 1024x768), but run faster allowing very short display times under lower resolution (e.g., 640x480).
640x480, 800x600, 1024x768, up to 1600x1200 and above
DirectRT will automatically switch the display to the resolution set here and then set it back to the default monitor settings when the session is complete. Note that text and images will appear smaller under higher resolutions than they do in lower resolutions. This is because it takes less screen space to display the same number of pixels. Make sure you consider what resolution you will run your session in when sizing your images and text. For example, a 640x480 image like ones in the samples will fill the whole screen in 640x480 mode, but only about half the screen in 1024x768 mode.
Note that the display size you choose here may have an impact on your refresh rate. Many computers will store a unique refresh rate for each resolution they support. This means setting the refresh rate for one resolution doesn't necessarily set it for all available refresh rates. The trick is to manually set your display to the desired resolution through the display settings in the Windows Control Panel, and manually set the refresh rate while you're there by clicking on the display's advanced settings. Whatever refresh rate you set here is what DirectRT will be using when it enters this specific screen resolution.
DirectRT asks your system about what it can handle and will allow you to run sessions using any resolution your monitor will allow. Taking advantage of this features means you will want to ensure other computers on which you want to run the sessions also are able to use the chosen resolution. The values 640x480, 800x600 and 1024x768 are usually safe on most systems.