Node graph architecture

Node graph architecture is a type of software design which builds around modular node components which can be connected to form a graph. Often the software's underlying node graph architecture is also exposed to the end user as a two-dimensional visualization of the node graph. The node graph architecture is popular in the film and computer games industry.

There are often many different node types participating in the node graph. For example, in the Nuke Manual they list hundreds of nodes. Each node type performs one specific task. For example, Nuke's Merge node produces an output image in which a number of input images have been layered. By connecting many different node types together complex image effects can be produced.

The node graph architecture often allows grouping of nodes inside other group nodes. This hides complexity inside of the group nodes, and limits their coupling with other nodes outside the group. This leads to a hierarchy where smaller graphs are embedded in group nodes. In Nuke the group node is simply called the Group node.

In the paper Hierarchical Small Worlds in Software Architecture they argue that most large software systems are built in a modular and hierarchical fashion, and they use node graphs to analyze large software systems. In fact a large number of software analysis papers often use node graphs to analyze large software systems suggesting that node graphs are good models of the internal structure and operation of the software.

Many commercial and non-commercial software systems allow users to visualize and interact with internal components via the node graph. Below are a number of node graph based software applications from the film and games industry.

Grasshopper 3D is a procedural/parametric modeling add-on that runs within the Rhinoceros 3D computer-aided design (CAD) application. The nodes in its graph can be connected to create complex geometry for design and architecture.

Nuke is a compositing application for film made by The Foundry. The nodes in its graph can be connected to produce complex 2D image processing effects.

Shake is a discontinued compositing application for film made by Nothing Real LLC and later purchased by Apple. The nodes in its graph can be connected to produce complex 2D image processing effects.

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