Table of Contents
Import Analog Signals From AMTI Ascii File
This command will import analog signals in from an ASCII file written out by AMTI force plates. As with all commands, it acts on all active files in the Visual3D Workspace.
NOTE: The name of the ASCII file should be the C3D file name suffixed with “_a”, for example test_a.txt and test.c3d. See Important Notes for more details.
Pipeline Command
The command can be found in the Pipeline Workshop within the File Open/Import folder as so:
Import_Analog_Signals_From_Amti_Ascii_File ! /FREQUENCY= ! /REPLACE_EXISTING_SIGNALS=TRUE ! /FOLDER= ;
Command Parameters
The following table shows the command parameters seen above and their descriptions:
| Parameter | Description |
|---|---|
| Frequency | The frequency at which the ASCII file's analong signals were collected. |
| Replace Existing Signals | If true, then any existing analog signals in the C3D file matching Visual3D's default names will be replaced. |
| Folder | The name of the ANALOG folder into which the signals should be imported. By default this is the ORIGINAL folder. |
Interpreting the AMTI ASCII File Format
AMTI's ASCII file format contains 6 signals which, for example, would appear as:
-0.7106 , 0.0000 , 0.0000 , 0.0000 ,-22.4939 , 11.1253 -0.7106 , 0.0000 , 0.0000 , 0.0000 , 0.0000 , 11.1253 -0.7106 , 0.0000 , 0.0000 , 0.0000 , 0.0000 , 11.1253 -0.7106 , 0.0000 , 0.0000 , 0.0000 , 0.0000 , 11.1253
Visual3D assigns default signal names to these 6 signals located in the ANALOG::ORIGINAL signal folder:
- A001
- A002
- A003
- A004
- A005
- A006
If these names already exist in the C3D file, then Visual3D's behaviour is guided by the command's /Replace_Existing_Signals parameter. If this is true, then the existing signals are replaced, otherwise the default signal name is incremented again.
Important Notes
File Naming
In order to automate the processing of many files, Visual3D assumes that the ascii file as the same name as the c3d file, but .c3d is replaced with _a.txt. For example:
C3D file = c:/test.c3d AMTI ASCII file = c:/test_a.txt
Analog Rate
The command assumes that the user is specifying the analog (sampling) frequency because this information is not contained in the data file. The analog frequency must be an integer multiple of the C3D file's motion capture (point) sampling rate. This command does not resample the data.
Unmatched Frames
If there are more samples of ANALOG data than would fill corresponding frames of motion capture data, then Visual3D will just add the additional frames.
If there are too few frames, the signal is buffered with zeros at the end.