Node graph architecture
Encyclopedia
Node graph architecture is a type of software design which builds around modular node
Vertex (graph theory)
In graph theory, a vertex or node is the fundamental unit out of which graphs are formed: an undirected graph consists of a set of vertices and a set of edges , while a directed graph consists of a set of vertices and a set of arcs...

 components which can be connected together to form a graph
Graph (mathematics)
In mathematics, a graph is an abstract representation of a set of objects where some pairs of the objects are connected by links. The interconnected objects are represented by mathematical abstractions called vertices, and the links that connect some pairs of vertices are called edges...

. Often the software's underlying node graph architecture is also exposed to the end user as a 2 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.

Commercial applications

Nuke
Nuke (software)
Nuke is a node-based compositor produced by The Foundry, and used for film and television post-production. Nuke is cross-platform, and is available for Microsoft Windows, Mac OS X, and Linux...

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

Shake
Shake (software)
Shake is a discontinued image compositing package used in the post-production industry. Shake was widely used in visual effects and digital compositing for film, HD and commercials. Shake exposes its node graph architecture graphically. It enables complex image processing sequences to be designed...

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

Maya is a modeling, animation, and rendering application made by Autodesk
Autodesk
Autodesk, Inc. is an American multinational corporation that focuses on 3D design software for use in the architecture, engineering, construction, manufacturing, media and entertainment industries. The company was founded in 1982 by John Walker, a coauthor of the first versions of the company's...

. The nodes in its graph are more general and produce 3D geometry and various other attributes.

Houdini
Houdini (software)
Houdini is a high-end 3D animation package developed by Side Effects Software which is headquartered in Toronto, Canada. It is a rewrite of the PRISMS ecosystem of standalone tools. Its chief distinction from other packages is that it has been designed as a purely procedural environment...

 is a procedural modelling, animation, and rendering application made by Side Effects Software. The nodes in its graph produce procedural geometry. Side Effects Software refers to their node graphs as networks.

Valve's Source SDK allows players to create custom maps for all of their games. The nodes in its graphs are used in AI path planning and also in sending signals between game entities.

Open source applications

Blender is a modelling, animation, compositing, and rendering application. The nodes in its graph produce images, 3D geometry, and various other attriutes.

NodeBox is procedural image creation application. The nodes in its graph produce vector based images.

In-house studio applications

Many large movie studios are rumored to be using the node graph architecture to design many of their in-house software tools. Sony Pictures Imageworks uses an in-house compositing and lighting tool called Katana. In a recent press release (November 2009) it was announced that the Sony Pictures Imageworks' Katana software would be integrated into The Foundry's Nuke software.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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