Touch Marker
 | Touch Marker | Receiver for unique marker objects such as fiducial, bar-coded objects, and so on. |
Camera based MultiTouch systems often support the recognition of uniquely marked objects. For example, a glass might have a barcode underneath it and when placed on the tracking surface, a special menu shows the user a selection of dishes that go well with this drink.
The interpretation of markers, if supported, and the ID that corresponds to each object's pattern is done by the tracking software that comes with the MultiTouch hardware, not Ventuz. Please refer to your hardware's manual to find out more about marker support and what IDs are generated.
Ventuz supports marker objects sent by the TUIO protocol (i.e. 2Dcur messages) in that it recognizes them as no ordinary touches. Since TUIO only transmits position information - not camera images - a touch marker is transmitted as a touch position update with a unique ID (integer) that identifies the marker.
A Touch Marker node is bound to a specific touch marker by setting the MarkerID property to the respective ID assigned by the touch hardware. The node will fire events when the marker is placed on the table or lifted from it. It also provides the X/Y position as a float value from 0 - 1 and the angle of rotation in degrees. Unlike the other interaction nodes, the Touch Marker currently has no implicit behavior and therefore only acts as a value provider. Other Nodes, such as the Expression Node, will need to be used to change the raw 0 - 1 TUIO value to the screen coordinates needed in the project.
Ventuz only supports one object for a certain ID at the same time. The behavior if multiple objects with the same ID are placed on the tracking surface is undefined.
The X and Y output values are no longer in Pixels, it now gives out values between 0 and 1
The Touch Marker Node is the only node that reacts to marker objects. Marker touches and positions from the MultiTouch hardware cannot be used with any of the other Interaction Nodes.