Options specify the viewing parameters as well as giving some control over the calculation.
In the second form, the default values for the options are printed with a brief explanation. In the third form, the list of supported output devices is displayed. Rview starts rendering the image from the selected viewpoint and gradually improves the resolution of the display until interrupted by keyboard input. Rview may also stop its calculation and wait for command input if the resolution of the display has reached the resolution of the graphics device. At this prompt, the user can save the image, quit, or even restart a new image, although this is not generally recommended on virtual memory machines for efficiency reasons.