US Patent 10012722 Monitoring apparatus and non-transitory computer-readable medium

A monitoring apparatus is provided. When a determination process of determining whether or not the part of an object located in a search range is an airborne substance, a rangefinder measures a distance to the object located in the search range for each of a plurality of unit areas forming the search range, a variation measure calculator calculates a variance of the distances (individual distances) measured for the respective unit areas, a variable threshold setter variably sets a variation measure threshold based on the individual distances, and a determiner determines that at least part of the object is an airborne substance if the calculated variance exceeds the variation measure threshold.