The methods for determining the probability of detection of a thermally
camouflaged target at various ranges by the sensor includes determining
an "inherent" temperature difference, .DELTA.T.sub.RSS, between the
target and its immediate surroundings. Once .DELTA.T.sub.RSS is
determined, a scaled N.sub.50 cycle criterion, or the number of
resolvable cycles needed by the sensor for a fifty percent probability of
detection, is determined according to the relationship
N.sub.50=A/(.DELTA.T.sub.RSS).sup.B+C, where A, B and C are constants
that are predetermined according to whether the immediate surroundings
are of a woodland or a littoral nature. The scaled N.sub.50 cycle
criterion is then used in an empirical Target Transfer Probability
Function (TTPF) defined by P=(N/N.sub.50).sup.E/(1+(N/N.sub.50).sup.E),
where E=2.7+0.7(N/N.sub.50), in order to determine the probability of
detection of the thermally camouflaged target.