In complex applications, the assimilation of information from many diverse sources. A data-fusion problem exists when a wide range of data essentially relates to the same problem despite being in many different forms and modalities, e.g. visual, textual, sensory, graphics. A classic example is the task performed by air-traffic controllers, who are able to assimilate, filter, and respond to many channels of data in order to assess a given situation. Although many techniques exist for associating, correlating, extracting, and combining data, this remains a very difficult area to automate. When only sensory data is involved the topic may be known as sensor-data fusion.