Using an infrared camera

Introduction

Using a forward-looking infrared camera (FLIR) a series of images were taken in both standard visible light and in infrared (IR). This was to demonstrate the properties of an IR camera and to demonstrate some of the advantages and drawbacks of using an IR camera. In lab 2 IR sensors were used, one handheld device that was easy to walk around with, the other was a DJI Zenmuse XT2 on a DJI M600, the M600 was only used as a stable platform over a sous vide cooker (figure 1).

Figure 1

Methods

IR cameras allow for some interesting effects to be seen that otherwise wouldn’t have been. For example, seen in figure 2, there is a cold can of soda and a mug that is filled with boiling water. The water appears bright white on the camera indicating that it is the hottest thing that the camera is detecting. After lifting up the mug one can see that some of the heat was transferred to the table and made a bright white ring where the mug was previously (figure 3).

Figure 2

Figure 3

The next thing that the handheld IR sensor was used on was the air condition vent in the ceiling. The vent was outputting cold air which made the surrounding ceiling tiles appear orange and warmer. The image filter on the color purple/magenta indicates the cold surface that is being cooled by the air.

Figure 4, a filter was applied to color the image but the sensor still worked the same

A thermal camera can also be used to see hot exhaust out of a jet engine. It can see hot spots on  devices that are in use seen in figure 5 and 6

Figure 5, Hot jet exhaust

Figure 6, The FLIR camera generates a lot of heat

Discussion/ Results

An IR sensor can be very helpful in identifying heat or lack of in specific areas. This can be helpful where just visual light won’t help. Although IR seems to be very beneficial it does have some drawbacks. On surfaces that reflect light easily, there can be some issues, for example, a tree's leaves can appear black or white depending on the angle they are, which can make combing an area for specific heat values and signatures difficult with an unmanned platform. Another feature that can make IR sensors difficult to use is the fact that they cannot “see” through the glass. If one were to point an IR sensor at glass there wouldn’t be any heat signatures behind it. Glass can act as a mirror in this situation and reflect back heat that is behind the camera though, seen in Figures 7 and 8. Figure 7 is a normal camera view, while figure 8 is an IR view with an RGB overlay, seen in the outline of the student on the other side of the glass

Figure 8, the thermal view reflecting from behind the camera
The outline is the student behind the glass

Figure 7, a student standing behind a glass window

Conclusion

IR sensors are very helpful in many situations but they do have drawbacks. As they don’t typically include an RGB sensor distinguishing objects from one another solely based on the heat signatures given off can be difficult. Due to the difficulty of seeing through the glass and how plants can affect readings, there can be some difficulties in using IR sensors but as long as those are kept in mind when looking in at the data and if possible couple the IR sensor with an RGB sensor then the few drawbacks that are present can be mitigated.