Glossary

Generator Class

A class derived directly or indirectly from the xn::Generator class.

Generator Node

A node instantiated and created from any one of the generator classes.

Node Alternative

Any existing (already created) node or plug-in that satisfies an enumeration query. The nodes are checked first.

See also Understanding the Create() method

Frame Objects

A generator node's metadata object is a frame object containing a saved data frame from the node, and all the data frame's associated properties. For example, a DepthMetaData object is for containing a depth map 'frame object' from the DepthGenerator node.

In principle, an application can save a number of frame objects, each in a different metadata object.

The frame data can also be accessed directly from the generator node - by using the node's GetData() method.

Thus:

		metadata == frame object { <br>
		   frame data <br>		
		   frame configuration <br>
		} <br>
	
		generator 'outputs =>' frame object == frame configuration + frame data <br>
		<br>
	

This means that a generator node outputs the frame object, and the frame configuration is copied from the original configuration at the time of the generation of the frame object.

Typically:

		current configuration = frame configuration
    

For more detailed information about frame objects, see Frame Objects and Metadata Objects.

Frame Data (Data Frame)

The map generated from the node. This map is contained in the node's frame object.

Frame Configuration

The frame configuration associated with a generated data frame.

Holder Node

The term 'holder node', is used in regards to a capability object. The 'holder node' is the production node that a particular capability object is associated with.

Meanings of 'User'

This document uses the term 'human user' when referring to the human user seen by the sensor. The term 'user' refers to OpenNI's internal representation of human users that are pre-calibration or are being calibrated. The term 'skeleton' refers to skeletons that are, by definition, after calibration. The term 'skeleton' refers to the on-screen graphic representation of the skeleton.

Updating Nodes

'Updating' a node means that the node puts new data in its application buffer so that the application can access it.

On updating a node that did not have new data generated, the available frame object remains the same.

The application can access a node's data by calling the node's GetData() method.

If a node has an associated metadata object, an application can access the node's data through the metadata object by calling the node's GetMetaData() method, e.g., GetMetaData().