One of the most effective tools for getting past camouflage is thermal imaging (TI). A warm body can be detected by the heat it gives off with thermal imaging equipment and provides a formidable challenge to someone wishing to avoid detection. Visually, the gillie suit is one of the finest concealment tools, but a warm body inside one stands out clearly in an infrared scope. There is no absolutely certain way to defeat infrared, but there are some techniques that make detection more difficult.
Conceal yourself behind shards of glass. Glass is opaque to thermal imaging, but carrying around a pane of glass in the jungle is not terribly practical. In junk yards or urban settings, a broken window or shards of glass can break up the shape of a human body and make a person in a gillie suit harder to detect.
Throw a blanket over yourself. Afghan guerrillas carry thick woollen blankets to help defeat thermal imaging. A thermal blanket works the same way. By covering themselves with a layer of insulation, the heat is blocked so that it doesn't radiate. This only serves as a temporary concealment as the heat builds beneath the blanket, but may work long enough to conceal during a quick TI scan. Partially covering the gillie suit may also obscure the outline of the body enough to deceive TI equipment.
Hide next to warm stones that still hold heat from the day. The extra warm spots will confuse the thermal imagers. Vent pipes near buildings, thick walls or any source of heat can help obscure your thermal outline. Hiding in hollows or caves or piling irregular mounds of earth over you may make you look like a brush pile that's warm inside. Most brush piles emit a little heat that confuses an infrared image to the observer. The trick with terrain blocking is to make yourself look less like a human.
Attach materials of varying reflectivity and ability to absorb heat to the gillie suit to reduce the clarity of the body outline is to . Use odd shapes with varying thicknesses attached beneath the netting to vary the intensity of the heat given off by the body. This will not totally disguise your shape, but with other methods, can make concealment easier.
Wear double layers of material like insulated underwear with irregular venting between the net and clothing can help temporarily improve the break-up of the TI image. A wetsuit worn underneath the gillie suit can help keep heat in. All of these last only until the gillie suit wearer heat up inside the insulating layers and body heat begins ot leak out. The heat can also make it difficult for the wearer to operate effectively by overheating him and sapping strength.
Apply substances like wet mud to the face and exposed areas that might radiate heat. The cool mud streaked irregularly over hands and face can artificially cool the most open sources of thermal image. In a pinch, pour cold water over yourself. It can cool your skin and temporarily defeat a quick thermal scan. Rolling in the mud, suit and all can temporarily disguise your heat signature as well.