Why would a thermal camera register a reflection as a heat source?


I was watching a clip from a livestream of a safari where they were showing off their thermal camera by filming a hyena in the dark. It was near water and it’s reflection in the water had a purple glow to it though not as bright as the actual body.

In: Technology

A thermal camera is simply one that sees infrared radiation. Everything emits some form of light, hotter things emit higher energy forms of light, for instance a hot iron rod will glow red because it is hot enough to emit visible light.

Most warm blooded animals are hot enough to emit infrared radiation. All these forms of radiation behave as the same principle, just as visible light reflects off surfaces so does infrared.

The fact that its purple likely is because water doesn’t reflect everything, some goes into the water itself and the way the camera works is that less radiation means more dark colors like purple.

I do thermal photography at work and you would think it’s easy, just aim and click.

If I’m taking a picture of an electrical panel and there is an overhead light behind me, I can see it’s reflection on the metal. If I am well lit and standing square to the metal, I can see my reflection.

When taking thermal pictures, any surface from a full sheen to full polish will act as a mirror. If a surface can reflect light, it can reflect thermal energy.

Infrared energy is basically light at a frequency shorter than our eyes can see. An IR camera takes the high frequency light and represents it at light frequencies that we can see on a video screen or as a picture.