Tutorial 2: Using the Biped2 Filter

Purpose

The purposes of this tutorial are:

to explain the calibration process using previously captured data
to introduce the Biped2 filter
to demonstrates the uses of the Biped2 filter
to introduce the concept of raw sampled data

to demonstrates motion capture using the Ascension Flock of Birds driver.

To use this tutorial, you must copy the clip project into a convenient local project directory. If you have not already done so, follow the instructions in the Introduction on page 135 to obtain the example data.

Retrieving Models

Start MotionSampler and select File Retrieve Model to load the wire file Tutorial2Set.wire.
Select File Include Model to include the model Tutorial2Alian.wire.
This adds the model without deleting what was already there in the same way that loading a second file in Alias works.
Use the view controls buttons to move back and rotate the view to obtain a good view of the alien character and the set as follows:

Notice that the character is embedded in the floor of the set. This is because the character was built around the origin, as was the floor. This problem is corrected later in this lesson with an Offset module.

Constructing a Pipeline

The Biped2 filter and BipedTalent source modules are used to construct a pipeline to play back raw sample data on this character.

Click the pipeline button to display the pipeline editing area.
Create the following modules: the BipedTalent and ImportXform sources from the Source Modules list, the FloatSplit, FloatJoin, Offset, and Biped2 filters from the Filter Modules list, and the DAGGroup from the Sink Modules list.

Recall that modules are created by highlighting their names in the lists and then clicking the Use Module button, or by double-clicking on their names.
Arrange the modules as follows:

The data from the ImportXform module, which reads a raw sample file, and the BipedTalent is used by the Biped2 filter to find a joint solution for the character.
The FloatSplit, FloatJoin and Offset filters are used to alter the translation values in Y to bring the character up out of the floor.

The DAGGroup provides a convenient mechanism for distributing the output of the Biped2 filter on a large number of dag nodes in a wire file. This could be accomplished using the DAG sink as in Tutorial 1, but since the Biped2 hierarchy contains sixteen nodes, the pipeline editor would be clogged with modules and pipes.

The DAGGroup filter has no inlets and the ImportXform source has no outlets. Both of these modules create their inlets and outlets as needed based on the specifications of the data files or their configurations.

Editing a Module

Select Edit from the DAGGroup's menu.

The following window appears:

The syntax statement at the beginning is the usage statement for creating inlets and mapping them to dag nodes.

The <inlet_name> can be any text name, while the <node_name>:<channel>[.<axis>] must match an actual dag node in the file.

For example, the following specification:

inlet Neck NECK:R

creates an inlet called Neck whose data is placed on the rotation channels of the dag node named NECK in the wire file.

The following specification:

inlet Neck NECK:R.X

attaches the data only to the X rotation of the dag NECK.

The characters R, T, and S stand for rotation, translation and scale respectively, while the channel names X, Y, Z refer to the coordinate system.

In one of the above cases, a 3 component connection is specified where in another case a single floating point connection is specified. These differences in data types are shown by the color of inlets and outlets in MotionSampler.

Creating Standard Biped2 Inlets

The following describes how to create a series of inlets that map data to the standard dag names for the Biped2 filter. Although you have to type in these inlets, the data is saved with the filter when you save the pipeline.

Edit the DAGGroup module to reflect the following inlets:

MotionSampler provides predefined modules that have built-in configuration files. These modules are listed as Predefined Modules in the lower right corner of the Module library lists.
Double-click on the DAGGroup:Humanoid sink.

Sinks are identified as K, sources as S, and filters as F. This predefined module matches what you have just typed in, and is provided as a convenience.
Delete the sink you just created by selecting Delete from its menu.

With the DAGGroup set up, the pipeline screen should resemble the following:

Connecting Biped2 Outlets

You can now connect the outlets of the Biped2 filter to the DAGGroup sink.

The inlets of the DAGGroup are carefully named to match the outlets of Biped2, so the connection process is quite straightforward. You can also connect the BipedTalent to the talent inlet on the Biped2 filter.

Try using Shift-drag and Ctrl-drag to connect these inlets and outlets so that they appear as follows:

Leave the FloatJoin, FloatSplit and Offset filters detached for now.

For the ImportXform source to define its inlets, you have to specify a filename for the module to read the raw data from.

Return to the View mode.
Click on the downward pointing arrow beside ImportXform in the Toolbox area as follows:

The ImportXform area appears as follows:

Notice that no filename is specified at Current File.
Click the Set File button. The following File Browser appears:
Select one of the raw sample data files (they are found in the subdirectory misc_data/rsd in the example files) and click the OK button.

Once you have selected a filename, the ImportXform source determines an appropriate set of outlets.

Return to the pipeline editing mode. The ImportXform source now has outlets.
Connect the outlets to the corresponding inlets of Biped2 as in the following:

Executing the Pipeline

The pipeline is almost ready for execution.

Return to the View mode.
Click the downward pointing arrow beside the Biped Talent interface in the Toolbox area as follows:

The Biped Talent interface is displayed as follows:

Click the Get button beside the human figure. A File Browser is displayed as follows:

Select the talents file talents.tal and click the Retrieve button. This displays the Biped Talent Browser as follows:

Select one of the actors, either Lawrence or Marlon, from the Talents list. Select the Calibration as MC_ALIAN. Click the OK button to load the talent with the MC_ALIAN calibration.

The BipedTalent loads the data from the calibration of the actor Lawrence as the character ALIAN. This way, many character's calibrations for a single actor can be stored together.

The example raw motion sample files that were recorded with Lawrence as the actor are marked with an L, while those with Marlon are marked with an M. If you match the talent to the raw sample data, your results will be better.

Press the F1 key to begin Sample mode.

If everything has been connected correctly, the character will begin to move according to the raw sample file you chose earlier. You can use the interface to select other raw sample data if you want.

You may need to adjust your view to see the character moving as follows:

Correcting Movement with Offset

As you can see, the character is moving through the floor. The Offset module is used to raise the character above the floor.

Press the F1 key to stop Sample mode.
Click the pipeline button to return to the pipeline editor.
Disconnect the DAGGroup's Position inlet by selecting the inlet and dragging the connection up and away from the module.
Connect the remaining modules as follows:

Biped2 outlet P to FloatSplit inlet X
FloatSplit outlet X to FloatJoin inlet X
FloatSplit outlet Z to FloatJoin inlet Z
FloatSplit outlet Y to Offset inlet F
Offset outlet F to FloatJoin inlet Y
FloatJoin outlet X to DAGGroup inlet P.

Your pipeline should appear as follows:

Click the single view button to return to Single View mode and press the F1 key to return to Sample mode.

Click the downward pointing arrow beside the Offset module's controls in the Toolbox as follows:

The Offset interface opens to show sliders for scale and offset as follows:

Slide the offset slider until the character emerges from the floor (the approximate value is 50.0) with the system still in Sample mode.

The character should appear as follows once you have adjusted the offset correctly:

Adjusting Calibration Values

This kind of real time adjustment is central to MotionSampler. You can also adjust the calibration values in real time as follows:

Close the Offset filter's controls and open the BipedTalent controls.
Click the Chest sensor button at the center of the chest. When you click this sensor, the box appears pushed in.

Adjust the Sensor: Chest X slider below the human figure. Notice the effect on the upper body as in the following:

Since the ImportXform source is reading raw sensor data, you can practice calibration (and learn the effects of the various controls) without the expense or complexity of running the motion capture gear. Several raw sample data files that contain calibration motions are provided.

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