System information

Glossary-10 Vicon MX Hardware System Reference
narrow field of view. Zoom lenses have
variable focal lengths.
Foot contact A temporal parameter
used in gait analysis for the point in time,
or the percentage of the gait cycle, where
the foot hits the ground. Also see Foot off
and Gait analysis.
Foot off A temporal parameter used in
gait analysis for the point in time, or the
percentage of the gait cycle, where the
foot leaves the ground. Also see Foot
contact and Gait analysis.
Force A vector quantity that tends to
produce an acceleration of a body in the
direction of its application. Force is used
to describe the action of one body on
another, which may be direct, such as the
foot pressing on the floor, or indirect,
such as the gravitational attraction
between the body and the earth. Also see
Force plate, Moment, and Vector.
Force plate Also referred to as a force
platform. An electromechanical device for
measuring kinetic data as a subject
makes contact with or applies force to the
platform. The force plate gives electrical
signals proportional to the component 3D
forces and moments. Vicon application
software can record and analyze the
analog signals from supported third-party
force plates integrated into a Vicon
system. Also see Analog, Datastation,
Force, Kinetics, and MX Control.
Forward dynamics (kinetics) The
process of calculating the position,
orientation, velocity, acceleration,
angular velocity, and angular acceleration
of the elements of an articulated
structure, given the force and moment
(torque) applied to those elements and
their mass and inertia. Also see Forward
kinematics, Inverse dynamics (kinetics),
Inverse kinematics, and Kinetics.
Forward kinematics The process of
calculating the position and orientation of
the elements of an articulated structure,
given the angles at all the joints
connecting those elements. This is a fully
determined problem with a unique
solution. Also see Forward dynamics
(kinetics), Inverse dynamics (kinetics),
Inverse kinematics, and Kinematics.
Frame A complete video picture
composed of two scanned fields at a
specific period of time in a continuous
video signal. For example PAL video
contains 25 frames per second, and each
of these frames is made up of two fields
that together contain 625 horizontal lines
of video information. For non-interlaced
data, a frame is synonymous with a field.
For interlaced data, a frame is composed
of two fields: one even and one odd. Also
see Field, Frame number, Frame rate,
NTSC, PAL and Progressive video.
Frame number The sequential number
assigned to each frame of a video. Also
see Frame and Timecode.
Frame rate The number of times a
second the picture is updated to provide
the illusion of continuous movement. Also
thought of as the speed at which video
cameras capture data, frame rate is
measured in either frames per second
(fps) or camera frequency in Hertz. The
camera frame rate can be configured in
Vicon application software. In .avi files,
the frame rate refers to the rate at which
the video will be played back. Also see
.avi file, Frame, and Frame rate view
pane.
Frame rate view pane A type of view
pane in a Vicon iQ application software
window in which a range of diagnostic
real-time graphing views for all active
cameras can be displayed: frame rate,
mean residual, marker residual, marker
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