Thermal cameras are great if you want to get an idea of what’s hot and what’s not. However, if you want to use a thermal camera for certain machine vision tasks, you will generally need to perform a geometric calibration to understand what the camera is seeing and correct for lens distortion. (Henry Zhang) has shared several methods to do this.
To calibrate a thermal imager, you first need a thermal pattern. This is like the typical test image from a camera or screen, but with temperatures instead of colors. (Henry) explains several methods of doing this. One involves using a nichrome wire grid to create a thermal pattern for calibration purposes. Another uses cold aluminum discs inserted into a foam board. Even a simple checkerboard can work, with the black spaces warming more from ambient sunlight than their neighboring white dots. He then (Henry) explains the mathematical techniques used to calibrate based on these patterns.
It is a useful introduction to the subject if you are working with thermal imaging systems. We’ve also looked at other interesting machine vision topics before. If you have any great thermal imaging tips, feel free to drop us a line!