Definitions - Information Fusion in Signal and Image Processing - page 6

Incompleteness. Incompleteness characterizes the absence of information given
by the source on certain aspects of the problem. Incompleteness of the information
originating from each source is the main reason for fusion. The information provided
by each source is usually partial, i.e. it only provides one vision of the world or the
phenomenon we are observing, by only pointing out certain characteristics.
Ambiguity. Ambiguity expresses the possibility for an element of information to
lead to two interpretations. It can be caused by previous imperfections, for example,
an imprecise measure that does not make it possible to distinguish two situations,
or the incompleteness that causes possible confusion between objects and situations
that cannot be separated based on the characteristics exposed by the source. One of
the objectives of fusion is to erase the ambiguities of a source using the information
provided by the other sources or additional knowledge.
Conflict. Conflict characterizes two or more elements of information leading to
contradictory and therefore incompatible interpretations. Conflict situations are com-
mon in fusion problems and are often difficult to solve. First of all, detecting conflicts
is not always simple. They can easily be confused with other types of imperfections,
or even with the complementarity of sources. Furthermore, identifying and classify-
ing them are questions that often arise, but in different ways depending on the field.
Finally, solutions come in different forms. They can rely on the elimination of unreli-
able sources, on taking into account additional information, etc. In some cases, it can
be preferable to delay the combination and wait for other elements of information that
might solve the conflicts, or even not go through with the fusion at all.
There are other, more positive characteristics of information that can be used to
limit the imperfections.
Redundancy. Redundancy is the quality of a source that provides the same
information several times. Redundancy among sources is often observed, since the
sources provide information about the same phenomenon. Ideally, redundancy is used
to reduce uncertainties and imprecisions.
Complementarity. Complementarity is the property of sources that provide infor-
mation on different variables. It comes from the fact that they usually do not provide
information about the same characteristics of the observed phenomenon. It is directly
used in the fusion process in order to obtain more complete overall information and to
remove ambiguities.
The tools that can be used to model the different kinds of information and to mea-
sure the imperfections of the information, as well as redundancy and complementarity,
will be described in Chapter 6.