However, 3D software generally does not take into account the role of air in the shot, and in any case, the effect behaves like an overlaid distortion on top of whatever lays beyond the hot air from the point of view of the camera. You might think, therefore, that a physics model devised in 3D animation software would be more accurate than a 2D system.
In some cases it could be useful to generate the particles for heat distortion in a 3D animation package, if the distortion is located somewhere specific in a rendered scene and created by an animated object, such as the exhaust of a jet.
The lens is usually static and flat, but in the case of heat distortion, the abrupt mixing of fast-moving hot air particles rising into cooler ambient air causes ripples that have the effect of displacing and distorting what is behind the moving air, just like the ripples in the pool. Air is not a perfectly clear medium but a translucent gas that can act as a lens. There are cases in which our seemingly transparent atmosphere behaves like this as well, when ripples are caused in it by the collision of warmer and cooler air.Īs you know from basic physics, hot air rises and hot particles move faster than cool ones. Rippled waves in the water cause rippled bending of light. Stare into a swimming pool, and you'll see displacement caused by the bending of light as it travels through the water. A comparison with an unaltered shot of the building emphasizes the amount of distortion. The effect of heat haze has been added to the general mayhem being issued by the helicopter. When the fire itself is in the shot and you can see through it or anywhere above it, you expect the fire to heavily distort whatever is visible behind its heat.įigure 14.13. This adds to the visceral reality of the shot, whether it's a desert exterior, a day at the racetrack, or a jet engine exhaust.
When your eye sees heat distortion, it understands that a strong conflict, accompanied by an abrupt mix of hot air with cold air, is occurring. Its rippling effect adds to the dynamism or chaos of the scene. Like a lens flare, it's a highly visible effect that, if properly motivated and adjusted, lends realism to your scene rather than distracting from its story.įigure 14.13 shows the fabricated results of heat distortion in a scene. Heat distortion, that strange rippling in the air that occurs when hot air is dissipated into cooler air, is another one of those effects compositors love.
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