Fusion of Non-Simultaneous Elements of Information: Temporal Fusion - Information Fusion in Signal and Image Processing - page 233

Chapter 11
Fusion of Non-Simultaneous Elements of
Information: Temporal Fusion
11.1. Time variable observations
Temporal fusion of data allows us to handle instantaneous information, i.e. infor-
mation whose value is only valid at a given time. This fusion is used when the param-
eters obtained from observation vary with time.
The problem therefore is to track the evolution of these observations, as opposed
to an overall characterization of the evolution. The following example illustrates this
instantaneous nature: when observing a beating heart, the temporal fusion of data
makes it possible to estimate the instantaneous blood flow. With a non-temporal fu-
sion, it would be possible to estimate the mean blood flow over a long period of time.
On the other hand, temporal fusion would be needed to observe the evolution of the
mean blood flow depending on, for example, the evolution of the patient's level of
stress. This shows that we always have to define concepts related to time such as
“moment”, “evolution”, “period of time” according to the application because a length
of time can be “long” in certain cases, or “short” or even “negligible” in others.
Thus, temporal fusion involves the evolution or the modification of data:
- it may involve the modification of the object being observed. For example, when
analyzing the heart's movement, focus will be directed to its morphological modifica-
tions over time;