The Data and Information Fusion domains have for some time addressed the issues
involved with Situation Estimation and Situation Refinement as part of the
characterization of the "higher" levels of fusion processing, meaning those levels of
processing that deal with more abstract and complex world states of interest that people
call "situations". It is usually agreed however that at the moment at least the research in
the Data and Information Fusion (DIF) field has by far been on the aspects of estimating
single and sometimes multiple-object attributes from composite observational data, and
usually from electronic or physics-based sensing devices such as radars and imaging
systems, that is, on the so-called "lower" levels of fusion. As both the world and the
technology have changed, and as research in the DIF arena has matured, there has been a
considerable interest in directing the research to methods for estimating the higher state
levels of DIF, usually called Situation Refinement and Threat or Impact Refinement, and
related to "Level 2" and "Level 3" of the well-known "JDL" DIF process Model (Ref 1).
Note that the "refinement" term is important, implying an awareness of the fact that the
focus of DIF processing is almost always on dynamic events in the world; it also reflects
the need for a temporally-adaptive, recursive state estimation process.