With the rapid development of infrared detecting and homing technology, it is important for us to analyze infrared
camouflage effect of ground targets to improve the survivability. In the paper, factors such as the effect of atmosphere
between detectors and targets, characteristics of targets and background and atmospheric radiance including directly
transmitted solar irradiance are taken into account in long-distance detecting. The concept of RARD (relative apparent
radiance difference) between targets and background is proposed and the camouflage effect of ground targets can be
evaluated precisely. MODTRAN 4.0 is used to analyze the camouflage effect of targets. In MODTRAN, solar zenith
angle, common background, emissivity and temperature of targets are selected to calculate RARD under certain
atmosphere condition. Simulation results show that RARD is affected by the solar zenith angle significantly in middle
infrared wavelength region, but hardly in long-wave infrared region. Under the special background, according to the
target temperature, proper coating with unchanged emissivity is selected to camouflage the target all day in long-wave
infrared region. However, for the changing background, the stealth coating with variable emissivity should be adopted.
In addition, for the same target, it is even more difficult to achieve good camouflage effect at both medium infrared band
and long wave infrared band.