Rigid Frames
Overview
Rigid Frames are designed to be objects whose shape does not change, and as the name suggests
"rigid", such as a set piece like a table or box. Rigid Frames must have at least 3 LEDs assigned in order
for a solution to be created for the frame. There is no limit to the number of LEDs that can be assigned to
a rigid frame. If at any point less than 3 LEDs are visible for the specific rigid frame, tracking will stop.
This section outlines the creation of a rigid frame.
Creating a Rigid Frame
Create a rigid frame in the Body Frames widget. First, assign an ID to the frame.
To assign an ID to a frame.
Enter a numerical ID for the frame in the Frame ID box (Beacon ID) at the bottom of the Body1.
Frames widget.
On the drop-down list, click Rigid Body.2.
Click the green + button.3.
Result: The Rigid Frame is created and added to the list in the widget.
Once the frame is created, you may double-click and type a new name on the default name cell, and
press ENTER. By default, a Rigid Frame is given a name of 'RF(ID)'.
Assigning LEDs to a Rigid Frame
Assign LEDs to a rigid frame by dragging individual beacons from the global Beacons widget to the Frame
LEDs widget with a rigid frame selected in the Body Frames widget.
You must place the LEDs in the correct order on the object as well as in the Frame LEDs widget because
the first three LEDs assigned to a rigid frame defines the orientation of the frame.
The first LED corresponds to the origin of the local coordinate system of the object.
The second LED corresponds to the positive x-axis.
The third LED is special because it can be placed anywhere, but it defines the location of the
positive y-axis in the following way:
Placing the third LED somewhere in the same plane as LED 1 and LED 2, and taking the
cross product of the vectors from the origin to LED 2, and the origin to LED 3 will define
the positive z-direction of the local coordinate system of the rigid body. Use the right-hand
rule to determine the cross-product.
To perform the right-hand rule:
Place the side of the right hand, and place it along the line from the origin (LED 1) to1.
the positive x-axis (LED 2).
Curl the fingers of the right hand towards the line from the origin (LED 1) to LED 3.2.
The direction where the thumb points is the positive z-axis.3.
Once the first three LEDs are placed, any further LEDs added to the rigid body can be placed anywhere
and will be used as additional tracking points for the object, but are not required.
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