How to make perfect thermographic inspections: 4 tips to avoid mistakes
Not long ago, we said something about the innovations that the dronotics has made in the world of thermography (decreasing time, costs and dangerousness).
After detailing how these operations must be done and in which areas they are absolutely fundamental, today we will try to give some tips on how to make an excellent inspection work.
Some of the tips that we are about to give may seem like a way to ‘complicate’ the job, but do not be fooled: a delicate work of such an incredible usefulness need to be done in a very precise way and some trick can be more than useful.
4 tricks for the perfect thermographic inspection
1. Thermal imaging camera: it MUST be radiometric!
Let’s be banal: what’s the difference between a radiometric and a NOT radiometric thermal camera?
The latter are not conceived and designed to detect the temperature, but rather to detect the thermal energy present on a surface, in a non-invasive way, thus without making contact.
So these cameras merely show the temperature differences – so, any irregularities – but not the absolute value of the temperature.
On the contrary, the radiometric imagers are able to detect the absolute temperature of each surface (and of each pixel detected).
If you wanted to and make an inspection of photovoltaic panels, with a non-radiometric thermal imager you could only find the non-functional panels but would then need a further detailed analysis of the damaged panels with radiometric thermal imager.
It goes without saying, therefore, that installing on your drone a radiometric thermal imager helps us to skip a step further.
Or, even better, at the time of choosing the drone to work with, you can purchase a specific technical drone for thermography.
2. Mind the irradiation
Another little trick: it is better to fly the drone in the early morning or evening, because at other times of the day there is an excessive irradiation and then the results can be altered and even incorrect.
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3. Fly low
Flying at a height of over 10-15 meters you may not detect the details, which however is essential in this type of inspection works.
You should instead remain in the medium-low levels of overflight even if this implies to fly over an area more times, in order to allow the camera to shoot more frames that later will become parts of the relief.
This point is linked to the next tip, on which we devote a point apart:
4. Each height corresponds to a land resolution
Google Maps photos are 50 cm / px (each pixel corresponds to 50cm). The act of zooming in, useful to display a detail, reduces the image quality, which becomes 80-100 cm / px. For photogrammetry it is more or less the same, and you have to fly down to take detailed images which give detailed results; keep in mind that each unit corresponds to a resolution of the land.
You could even make a single photo from the top of a whole system of panels / building / land, but the detailed images would be completely invalidated.
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Have you ever made a thermographic inspection? what error you’ve done, that now you know how to avoid?