Описание тега msaa

Multi Sample anti-aliasing (MSAA) is a type of anti-aliasing, a technique used in computer graphics to improve image quality.

The term generally refers to a special case of supersampling. Initial implementations of full-scene antialiasing (FSAA) worked conceptually by simply rendering a scene at a higher resolution, and then downsampling to a lower-resolution output. Most modern GPUs are capable of this form of antialiasing, but it greatly taxes resources such as texture, bandwidth, and fill rate. (If a program is highly TCL-bound or CPU-bound, supersampling can be used without much performance hit.)

According to the OpenGL GL_ARB_multisample specification, "multisampling" refers to a specific optimization of supersampling. The specification dictates that the renderer evaluate the fragment program once per pixel, and only "truly" supersample the depth and stencil values. (This is not the same as supersampling but, by the OpenGL 1.5 specification, the definition had been updated to include fully supersampling implementations as well.)

In graphics literature in general, "multisampling" refers to any special case of supersampling where some components of the final image are not fully supersampled.

Source: http://en.wikipedia.org/wiki/Multisample_anti-aliasing