Alternate Frame Rendering (AFR) is a technique of graphics rendering in personal computer

Personal computer

A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...

s which combines the work output of two or more graphics processing unit

Graphics processing unit

A graphics processing unit or GPU is a specialized circuit designed to rapidly manipulate and alter memory in such a way so as to accelerate the building of images in a frame buffer intended for output to a display...

s (GPU) for a single monitor, in order to improve image quality, or to accelerate the rendering performance. The technique is that one graphics processing unit computes all the odd video frames, the other renders the even frames. This technique is useful for generating 3D video sequences in real time

Real-time computing

In computer science, real-time computing , or reactive computing, is the study of hardware and software systems that are subject to a "real-time constraint"— e.g. operational deadlines from event to system response. Real-time programs must guarantee response within strict time constraints...

, improving or filtering textured polygon

Polygon

In geometry a polygon is a flat shape consisting of straight lines that are joined to form a closed chain orcircuit.A polygon is traditionally a plane figure that is bounded by a closed path, composed of a finite sequence of straight line segments...

s and performing other computationally intensive tasks, typically associated with computer gaming, CAD and 3D modeling

3D modeling

In 3D computer graphics, 3D modeling is the process of developing a mathematical representation of any three-dimensional surface of object via specialized software. The product is called a 3D model...

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One disadvantage of AFR is a defect known as micro stuttering

Micro stuttering

Micro stuttering is a term used in computing to describe a quality defect inherent to multi-GPU configurations, such as nVidia SLi and AMD CrossFireX, using AFR...

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Parallel rendering methods

AFR belongs to a class of parallel rendering methods, which subdivide a four dimensional image frame sequence (x,y,z and time) into smaller regions, each of which is then assigned to a different physical processor within a multi-processor array. Note that the regional boundaries may be defined in space or in time. Also, the multiple processors can be implemented within a single video card or separate video graphics cards can be combined, subject to the motherboard and I/O slot limitations. When separate video cards are used, they must be specifically designed to allow a "cross-link" between them.

If a computer has two video cards that combine their outputs into a single video monitor, then one of three methods could be used to create the images.

• Alternate Frame Rendering (AFR): One graphics processing unit
  Graphics processing unit
  A graphics processing unit or GPU is a specialized circuit designed to rapidly manipulate and alter memory in such a way so as to accelerate the building of images in a frame buffer intended for output to a display...
  
  (GPU) computes all the odd video frames, the other renders the even frames. (i.e. time division)
• Scissors: One GPU renders the top half of each video frame, the other does the bottom. (i.e. plane division)
• Checker board: As the name implies, the image is split into smaller squares, which are assigned to different cards