Anti-Aliasing Theory

By default, the Maya Software and mental ray renderers operate with draft anti-aliasing settings. When preparing high-quality renders, it's therefore important to understand how to adjust the anti-aliasing attributes.

Anti-aliasing is the process by which aliasing artifacts are reduced. Aliasing artifacts result when an image is constructed with a limited number of pixels. Even a large-resolution render suffers from aliasing problems. For example, a 2048×1556 render is limited to 3,186,688 pixels. Although 3 million pixels may seem like an excessive number, they may not be sufficient to reproduce all the fine detail found within a 3D scene (detail may stem from intricate geometry, textures, and/or lighting).

When a render is created, a view plane grid is laid over the scene from the point of view of the camera. The number of grid rows and columns is established by the render resolution. Hence, each grid square equates to 1 pixel. Whatever lies within a grid square must be sampled to create a single red, green, and blue color value for the corresponding pixel. If multiple pieces of geometry, complex textures, or detailed shadows lie within the view of a single grid square, they still must be sampled. If no anti-aliasing methods are applied, only a single sample can be taken at a single point within the grid square. Hence, the resulting render is never as accurate as the original scene. The limited sampling leads to aliasing artifacts, which include stair-stepping, Moiré patterns, and buzzing.