Definitions - Information Fusion in Signal and Image Processing - page 2

This definition, which is largely the result of discussions led within the GDR-PRC
ISIS 1 workgroup on information fusion, is general enough to encompass the diversity
of fusion problems encountered in signal and image processing. Its appeal lies in the
fact that it focuses on the combination and decision phases, i.e. two operations that
can take different forms depending on the problems and applications.
For each type of problem and application, this definition can be made more specific
by answering a certain number of questions: what is the objective of the fusion? what is
the information we wish to fuse? where does it come from? what are its characteristics
(uncertainty, relation between the different pieces of information, generic or factual,
static or dynamic, etc.)? what methodology should we choose? how can we assess and
validate the method and the results? what are the major difficulties, the limits?, etc.
Let us compare this definition with those suggested by other workgroups that have
contributed to forming the structure of the field of information fusion.
Definition 1.1 is a little more specific than that suggested by the European work-
group FUSION [BLO 01], which worked on fusion in several fields from 1996 to
1999 2 . The general definition retained in this project is the following: gathering
information originating from different sources and using the gathered information to
answer questions, make decisions, etc. In this definition, which also focuses on the
combination and on the goals, the goals usually stop before the decision process, and
are not restricted to improving the overall information. They include, for example,
obtaining a general perspective, typically in problems related to fusing the opinions
or preferences of people, which is one of the themes discussed in this project, but this
goes beyond the scope of this topic. Here, improving knowledge refers to the world
as it is and not to the world as we would like it to be, as is the case with preference
fusion.
Some of the first notable efforts in clarifying the field were made by the data
fusion work group at the US Department of Defense's Joint Directors of Labora-
tories (JDL). This group was created in 1986 and focused on specifying and codi-
fying the terminology of data fusion in some sort of dictionary (Data Fusion Lex-
icon) [JDL 91]. The method suggested was exclusively meant for defense applica-
tions (such as automatically tracking, recognizing and identifying targets, battlefield
surveillance) and focused on functionalities, by identifying processes, functions and
techniques [HAL 97]. It emphasized the description of a hierarchy of steps in pro-
cessing a system. The definition we use here contrasts with the JDL's definition and
chooses another perspective, focusing more on describing combination and decision
1. www-isis.enst.fr.
2. This chapter greatly benefited from the discussions within this workgroup and we wish to
thank all of the participants.