Renderers can track each light ray as it travels through the scene on its way from the illumination source to the camera. Assume the light originates from a High Dynamic Range (HDR), spherically projected, panorama photographic environment. The HDR file enables the representation of continuous illumination intensity over a very wide range with contrast values, the range from light to dark, exceeding one million to one. These light intensities are cast inwards towards the sphere's center, located at the Origin.

In this scene, the panorama photograph depicts sunlight, filtered through a grape arbor, in an outdoor cafe during a tuscan afternoon. The renderer tracks a ray of sunshine cast from the panorama originating between the grape leaves and then striking a glass of red wine sitting on a creased blue checkered table cloth. The renderer calculates the ray's trajectory as it refracts, bending its path, first as it passes from air into glass, then glass into wine and wine back into glass, and finally, from the glass to the air and on into the camera. As it passed through the glass, the ray's color transformed into the deep red of the wine. When the ray algorithmically strikes the virtual camera's sensor, the wine's color is recorded in a pixel of the rendered image.

A second ray is then tracked as it emerges from the photographic representation of a translucent, living green grape leaf in the panoramic environment. This ray is less intense, and tinted green. The ray bounces off a crease running through a blue checker on the outdoor tablecloth and assumes a color that is primarily blue but containing a touch of green. The direction of the ray's bounce off the tablecloth is determined by calculating the angle at which the ray strikes the surface and the orientation of the point on the surface it hits. The orientation of a location on a surface is indicated by a directional vector, called a 'normal', that points in a direction perpendicular to the surface. In this case the normals of the crease on the tablecloth's surface caused the ray to bounce into the virtual camera.

A great many rays are cast and recorded in the rendered image. When rendering an animation, as the render engine completes one image, it begins loading and processing the scene for the next frame.