A lighting pass is an optional part of multi-pass rendering, that adds flexibility and control to the compositing process. Other lights are hidden or deleted when rendering the lighting pass. Effects passes may sometimes be rendered, depending on the needs of your project. An effects pass is a separate rendering of a visual effect or a mask for a visual effect. An effects pass might be an optical effect, such as a light glow or lens flare, or a particle effect, such as a cloud of smoke or plume of jet exhaust.
Some productions use depth maps rendered in a special depth map file format.
Other productions use simulated depth maps which are rendered as standard image files just like any other pass, but with a depth-fading effect over objects with constant white shading. Passes can be rendered one at a time by rendering differently modified versions of your 3D scene, or some software can set them up automatically or render more than one pass type at once. Memory can be saved by not putting every object into a rendering at once, making complex renderings possible on ordinary PCs. Changes can be made with little or no re-rendering. Other adjustments, such as adjusting the darkness of a shadow or the color of a glow, can be made without any re-rendering, just by adjusting your composite.