containing moving objects are grabbed by an
insufficiently rapid digitizer.
motion compensation
generation of a
prediction image, an interpolated or extrap-
olated frame, from pixels, blocks, or regions
from known frames, displaced according to
estimates of the motion between the known
frames and the target frame.
motion estimation
(1) process of estimat-
ing the displacement of moving objects in a
scene.
(2) strictly, the estimation of movement
within a video sequence, including camera
movement and the independent motion of ob-
jects in the scene. In practice, refers to the
determination of optical flow (the spatiotem-
poral variation of intensity) which may not
correspond to real movement (when, for ex-
ample, an object moves against a background
of the same color). Gradient-based methods
are based on the expansion of a Taylor se-
ries for displaced frame difference yielding
an “optical flow constraint equation”. This
must be combined with other constraints to
yield a variational problem whose solution
requires the iterative use of spatial and tem-
poral derivatives. Block-matching methods
rely on finding minimum error matches be-
tween blocks of samples centered on the
point of interest.
Frequency-based tech-
niques measure phase differences to estimate
motion.
motion measurement
the measurement
of velocities.
Usual motion measurement
techniques such as optical flow give incom-
plete and unstable results which must be
regularized by comparing velocities over a
whole moving object (the latter must first be
segmented).
motion segmentation
the decomposition
of a scene into different objects according to
the variation of their velocities. Motion seg-
mentation requires the measurement of ve-
locities across the scene.
motion stereo
a specific case in motion
estimation in which the 3-D scene is station-
ary and the only camera is in rigid motion.
motion vector
a vector displacement rep-
resenting the translation of a pixel, block, or
region between two frames of video, usu-
ally determined by optical flow calculation or
block matching (see motion estimation). For
instance, in the case of dense motion field,
say, an optical flow field, a motion vector is
assigned to each pixel on the image plane. In
the case of block matching for image coding,
a motion vector is assigned to each block. In
the case of computer vision, a motion vector
sometimes refers to the velocity of a point or
an object in the 3-D space. Sometimes mo-
tion vectors are referred to as displacement
vectors.
motional time constant
a material pa-
rameter that is inversely proportional to the
product of the frequency and Q-factor for a
particular mode.
motor
an electromechanical device that
converts electrical energy from a DC or an
AC source into mechanical energy, usually
in the form of rotary motion.
motor circuit
the three components of
an electrical circuit are source, load, and in-
terconnecting circuit conductors. A motor
circuit is an electrical circuit designed to de-
liver power to a motor. It includes the over-
current protective devices, controller, discon-
nect switch, circuit conductors, and the motor
itself, as shown in the figure.
motor circuit protector (MCP)
a listed
combination motor controller containing an
adjustable instantaneous-trip circuit breaker
and coordinated motor overload protec-
tion.
MCPs can provide short-circuit and
bolted ground-fault protection via the circuit
breaker magnetic element, overload protec-
c
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