Multisample anti-aliasing (MSAA) is a type of anti-aliasing, a technique used in computer graphics to improve image quality. In Digital signal processing, anti-aliasing is the technique of minimizing the distortion artifacts known as Aliasing when representing a high-resolution signal Computer graphics are Graphics created by Computers and more generally the Representation and Manipulation of Pictorial Data
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Definition
The term generally refers to a special case of supersampling. Supersampling is an Antialiasing technique the process of eliminating jagged and pixelated edges ( Aliasing) Initial implementations of full-scene anti-aliasing (FSAA) worked conceptually by simply rendering a scene at a higher resolution, and then downsampling to a lower-resolution output. In Digital signal processing, anti-aliasing is the technique of minimizing the distortion artifacts known as Aliasing when representing a high-resolution signal Most modern GPUs are capable of this form of antialiasing, but it greatly taxes resources such as texture bandwidth and fillrate. The fillrate usually refers to the number of pixels a Video card can render and write to video memory in a Second. (If a game is highly TCL-bound or CPU-bound, supersampling can be used without much performance hit. Transform clipping and lighting ( T&L or sometimes TCL) is a term used in Computer graphics. )
According to the OpenGL GL_ARB_multisample[1] specification, "multisampling" refers to a specific optimization of supersampling. OpenGL ( Open G raphics L ibrary is a standard specification defining a cross-language Cross-platform API for writing applications that produce The specification dictates that the renderer evaluate one color, stencil, etc. A Stencil buffer is an extra buffer, in addition to the Color buffer ( Pixel buffer) and depth buffer ( Z-buffering value per pixel, and only "truly" supersample the depth value. In Computer graphics, z-buffering is the management of image depth coordinates in three-dimensional (3-D graphics usually done in Hardware, sometimes in (This is not the same as supersampling, but by the OpenGL 1. OpenGL ( Open G raphics L ibrary is a standard specification defining a cross-language Cross-platform API for writing applications that produce 5 specification[2], 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. For example, a real-world multisampling implementation may also supersample stencil values. The lists below refer specifically to the ARB_multisample definition.
Advantages
- Pixel shaders need usually be evaluated only once per pixel. A pixel shader is a shader program often executed on a Graphics processing unit.
- Additional memory bandwidth is not required for multiple color/stencil/etc. samples.
- The edges of polygons (the most obvious source of aliasing in 3D graphics) are antialiased. This article applies to signal processing including computer graphics
Disadvantages
- Aliasing and other artifacts are still visible inside rendered polygons. In Natural science and Signal processing, an artifact is any perceived Distortion or other Data error caused by the instrument of observation
- Multi-pass rendering techniques may suffer when interacting with edges.
- Since stencil values are still per-pixel according to the specification, some strange interactions can occur at the edges of polygons when using techniques such as shadow volumes. Shadow volumes are a technique used in 3D computer graphics to add shadows to a rendered scene
References
- ^ ARB_multisample, "Additions to Chapter 3 of the 1. 2. 1 specification"
- ^ OpenGL 1.5 specification, section F. 3
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