When lighting a scene or model, software is used to produce a light source and predict the likely reflections and shadows caused by that light. However the processing and calculation required to accurately simulate light’s paths, refractions and reflections off of objects within a scene is quite demanding on a system. To circumvent this problem alternate lighting techniques have been developed. Ocular occlusion is one such technique that instead of calculating where the light will illuminate, it applies assumptions and uses the positioning of objects relative to each other and the light source to estimate where the shadows will fall.
Rendering a production applies the textures, shaders, lighting and animation to the models and scene. This process gives each element its final look. Essentially the final product and its final quality hinge on the elements it is comprised of, thus imputing quality effects onto a detailed model will give the most vivid rendered product.
Compositing is one of the post production processes wherein all of the rendered elements are combined layer by layer into the finished product. In essence compositing is the choreography of the animation industry, taking all of the envisioned elements and combining them. Regardless of if the individual elements of a production are of a high quality or not, if they are not sequenced and layered well the entire production can fail, thus compositing is arguably the most important production phase of an animated product.