Expression Items
Data_Tree
Signals should be placed into the expression in the form:
- SIGNAL_TYPE::SIGNAL_FOLDER::SIGNAL_NAME
To define a specific element of a signal (e.g. the X Component)
- SIGNAL_TYPE::SIGNAL_FOLDER::SIGNAL_NAME::X
To define a specific frame of a data of signal (e.g. Frame 2)
- SIGNAL_TYPE::SIGNAL_FOLDER::SIGNAL_NAME[2]
Data stored in the GLOBAL Workspace should be expressed as follows:
- GLOBAL::SIGNAL_TYPE::SIGNAL_FOLDER::SIGNAL_NAME
NOTE: Global signals can be accessed regardless of the ACTIVE FILES.
Examples for Specifying a Data Tree Signal
- TARGET::ORIGINAL::RFT1 = Signal RFT1 in the TARGET type and ORIGINAL folder
- ANALOG::PROCESSED::FX1 = Signal FX1 in the ANALOG type and PROCESSED folder
- PARAMETER::ANALOG::RATE= Parameter RATE in the ANALOG group of the C3D PARAMETERS
Model_Builder
Model metrics have a simpler syntax. The Signal Type and Signal Folder need not be specified because there is only one version of a signal.
Creating a Landmark at the center of a ball
- Given 6 markers placed on the surface of a round ball
- BALL1, BALL2, BALL3, BALL4, BALL5, BALL6
- Create a model metric at the center of a best fit sphere to the ball.
- Metric Name= BALL
- Metric Expression = Best_Fit_Sphere(List(BALL1, BALL2, BALL3, BALL4, BALL5, BALL6))
- The resulting metric will have 3 values separated by a comma (e.g. the 3 components of the center)
- As an example a center value of (0.5, 0.6, 0.7) would appear as
- 0.5,0.6,0.7
- Create a landmark using this metric data
- Note the syntax for the offsets
- BALL[1,1]
- The syntax may seem a little strange, but [1,1] refers to the first element of the first frame