Rayshade can take anywhere from seconds to weeks to render an image. The exact time required is a function of the speed of the machine(s) on which you're working, the complexity of the scene, and how ``good'' you want the final image to be. Creating a finished ray-traced image is an iterative process. Usually, many test renderings are made at low resolution and with non-essential features turned off. After each test image is created, surface definitions might be modified, the eye or look positions may be slightly changed, or the intensity of a light source changed.
This chapter describes the basic operation of rayshade and some of the options that control that operation. Setting these options properly can greatly reduce rendering time, improve the quality of your images, and make you a better person.
Rayshade usually works as a filter, reading a description from the standard input and writing an image file to the standard output. As it is working, rayshade reports on the progress of the rendering by writing messages to the standard error.