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Hello everybody, welcome to the FireScience show.
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In today's episode we will be talking about thermal cameras, and that's probably one of my most favorite devices that exist in the world.
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I would claim to say that if you have a fire safety engineering friend and you'd like to give them an amazing gift that they will enjoy a lot and the budget is on a little higher end and thermal camera is your way to go there.
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It's just fascinating to look through the world through the lens of thermal imaging, especially as soon as you start applying that into anything fire related and you see those harsh gradients between cold and hot surfaces, how stuff quickly cools or quickly heats up.
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It really gives another dimension to the eye of a fire safety engineer.
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But this episode is not just about fascination on thermal imaging.
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It's more about its practical side and the practical side in the life and safety.
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Thermal cameras are today a vital piece of equipment used by firefighters in the world to look further into the realm of fire when fighting fires, and we all understand how big advantage they can give to firefighters but also that a faulty thermal camera can be potentially life-threatening.
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So in this episode I've invited Martin Veit from Zag Frisbee, and Martin has just finished his report for the Fire Protection Research Foundation in which he was looking into different metrics of quality for thermal cameras thermal cameras that are actually being used by firefighters in the United States.
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In this episode we will dive a little bit deeper into the mathematical part of how to test different images and what does it mean to compare the image quality.
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But before we reach that point, we have a long discussion about the thermal cameras how do they work, why measuring temperature with cameras is actually quite difficult and why just observing the temperature gradient or differences in a fixed location is not that hard, what you can do with them, how do we test them and how can we improve it for the future.
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So let's not prolong this unnecessarily.
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Let's be in danger and jump into the episode.
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Welcome to the Firesize Show.
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My name is Wojciech Wigrzyński and I will be your host.
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The FireSense Show is into its third year of continued support from its sponsor, ofar Consultants, who are an independent, multi-award winning fire engineering consultancy with a reputation for delivering innovative, safety-driven solutions.
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And now back to the episode.
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Hello everybody, I am joined today by Veit from from Frisbee at ZAG in Slovenia.
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Hey, martin, good to have you in the podcast.
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Hello, thanks for having me and thanks for joining me.
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We have an interesting topic here to discuss and that is your very recent report for the Fire Protection Research Foundation at the NFPA, which is on measuring thermal image quality for fire service applications.
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I have not had a thermal imaging episode yet, but I think it is quite an interesting topic that actually connects engineers, firefighters, practitioners Come on, everyone likes thermal cameras in fire safety, so perhaps let's start with your background and how you ended up in this project, right?
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So for my background, I'm actually not a fire safety engineer, I'm a civil engineer and then I just stumbled into the field and I guess the first entry into the field was really when I was, I guess, cold called.
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So a guy from my university, when he went into industry, recommended me to a partner in a company called Vibraxenernen, kenneth Håkvar Jensen, and then he asked if I wanted to work in the company as a student helper.
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So I worked there for half a year, which was my first entry really into fire protection engineering, and I worked on multiple different things, so fire strategy, but also I worked a bit on documentation and programming and I was supposed to stay.
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But then I was offered a PhD.
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That didn't start immediately at Aalbe University, but I was supposed to start on that one Eventually.
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It took a bit too long for me, it didn't go as planned.
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But then Grunde Jomaas, my current supervisor, reached out to me on LinkedIn.
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But then Grunde Jomaas, my current supervisor, reached out to me on LinkedIn.
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I guess I liked LinkedIn posts.
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And then he wrote to me in Danish, I believe on LinkedIn.
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So I was very surprised and offered me a PhD in Slovenia.
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So I thought let's go back to fire protection engineering and then take an adventure.
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Go to Slovenia see what brings.
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So there are actually positive things from Grundy's LinkedIn activity.
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Good to know.
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Absolutely Exactly.
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Yeah.
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And how did you end up studying thermal cameras?
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Right.
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So I didn't have a background in fire protection engineering.
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So more or less the first half a year to a year was me figuring out what am I going to do in the PhD.
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And I think I ended up after a meeting with Andrea Licardini, another one of my supervisors.
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We had a meeting and then at some point we discussed okay, maybe it could be interesting to look into gas phase measurements, and so I started reading a lot, found some papers, and then I found a paper that used thermal imaging cameras to then characterize the flow field after pool fire, and so I looked into that a bit.
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But then I stumbled into the fact that thermal imaging cameras normally have pretty low resolution, both spatially and also the frame rate.
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So I thought, okay, how can we accommodate this problem, this issue, this?
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So I looked into how to improve resolution of videos, so both the spatial and temporal resolution, and I recently presented a paper on that in Greece, using some machine learning to then enhance video footage, specifically of thermal videos.
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And then at some point during this whole process, I think he received an email about something called student project initiatives from the FPRF, so the Fire Protection Research Foundation, and we looked into the projects that they had and one of them was specifically on measuring the thermal image quality.
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So I think from the beginning to the end, from my background and then ending up to where I am now, has been a big coincidence, more or less, into this project also.
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Welcome to World of Fire Science.
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I guess it's a common story.
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I guess nine out of ten people, I think so We'll have a similar life story about how they ended up in the current location where they are working or the topics that they are dealing with.
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Good, so a nice coincidence.
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I remember talking with you some time ago I think it was the conference in Slovenia about your ideas on measuring gas flow fields and using observation.
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It's kind of a holy grail in fire science to be able to incorporate more of optical measurements.
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They are fast, they are clean, they are easy Air quotes were shown while saying easy, because they're not very easy, but they look easy and it is my strong belief that you can get much more from recording fires and observing fires than you think you could get.
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But the technology that you're investigating here is not specifically meant to support researchers in their experimental endeavors.
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It's a technology used every day by firefighters, I presume.
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Can you tell me more about the types of cameras and the technology and how it is currently overwhelmingly used in the firefighting profession?
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Yes, absolutely so.
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Firefighters use this technology.
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So the thermal imaging camera or thermal imager, also called a TIC as a short name, and they use this for a lot of different of their duties when doing structural firefighting.
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So going into a building and then trying to navigate the building because you might have a building with a fire, you have a lot of smoke can be very difficult to see with your eyes, and then trying to navigate the building, much less identify a person lying on the floor if you can't see anything.
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So there was this nationwide study in the US I believe, where they looked into the efficacy of thermal imaging cameras and the way firefighters use them.
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So what they found was that if a firefighter goes into a building with a lot of smoke, they I think it was 60% of the times they couldn't identify a person without the thermal imager.
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But with the thermal imager they could identify the person 99% of the time.
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Also, it reduces a lot of the time it takes to locate a person.
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Also, navigate your way out of the building.
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So is it something that you could call, now, a standard piece of equipment?
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I wonder how it is around the world.
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I think in Poland the fire brigades are very strongly equipped with thermal imaging cameras.
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Right.
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So that is also my belief.
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So maybe in the 2000s, I think, when they started to route them out to firefighters and then before that, not so much because they were big, they were bulky, but then, when the technology then advanced, you can have a smaller thermal imaging camera, it's easier to use for the firefighter, and so on.
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So for now at least, also in the US, which was the main focus of the project, because it was an American project, it seems to be very, very common in the fire service to use this thermal imaging, and also I talked to some people in Europe as well which, as you also say, very common to use because it's such an effective equipment.
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I wonder when it's going to be equipped as a part of, you know, the helmet and the body kit itself.
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I can imagine this kind of device to be integrated with the helmet and the visor in the helmet to actually present some augmented reality, thermal imaging, over what the firefighter directly sees, perhaps with some clever eye tracking.
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I think every single component of technology that would be necessary to do such a thing already exists.
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It's just about you know, scale and being able to deliver that.
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So I'm absolutely convinced this is an element of infrastructure that will be a part of the future.
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And I remember when I rejoined the ITB 15 years ago, we had this massive, bulky thermal camera.
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It was like a beamer size, you know.
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You had to have a whole bag with that, and now a thermal camera that's significantly, significantly better in technology is of the size of my, of my iphone.
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That that's it.
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That's that.
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That's the progress in this technology you mentioned.
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They have low resolution, low frame rate.
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So how does that compare to devices that people are used to like cameras in their phones, if?
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you have a standard iphone, not necessarily the newest one, but you'll have full hd images right, so you can have very high resolution.
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If you take an image, you can easily discern details, you see a lot of colors, it's very clear, very visible.
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But then for the thermal imaging camera it has a resolution much lower than that.
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If you have like a, if you're going to have very expensive cameras that will have a high resolution, also high frame rate, but the ones that are more affordable, also to the fire service, will typically have a resolution of 240 times 320.
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That's like the common one I think my first phone had a camera of 240 times 320 and it's a very low resolution actually.
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Uh, what about frame rates?
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Are we talking about like single image per second?
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Are we talking something like a movie?
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24, 30 hertz?
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How do they operate in frame rate?
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To a large degree.
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It's actually pretty good for what you need to do if you want to operate a thermal imaging camera and then go into a building because you don't want it to lag too much or you have too much time in between individual frames because that might make it very difficult to navigate.
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So the ones that are nfpa approved so the ones that are very common in the us, typically have a frame rate of 30 hertz or even as high as 60 hertz, which is pretty good for a thermal imaging camera and an fpa approved.
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Is there a standard they refer to?
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Is there something that defines what they should do?
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Perhaps that's something we should refer the listeners to.
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Right, so the standards that goes into certifying these thermal imaging cameras in the US, so the NFPA standard, that's the NFPA-1801, which is currently being consolidated into 1930, I believe it is which also collects a few other standards into one big standard.
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But that's the standard that goes into testing and what this thermal imaging camera should be able to withstand.
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And also to do and in terms of what they see, I know also in my thermal cameras there's this annoying parameter which is the temperature range which I have to set.
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So those devices used by firefighters, do they operate in like whole spectrum of fire temperatures up to, like I don't know, 1200s, or they are narrowed down to a few hundred degrees?
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What's the target temperature range on those devices?
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So actually, the different temperature ranges.
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So it sort of depends from camera to camera and the NFPA-approved ones.
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But I believe there must be like a minimum range in the NFPA standard.
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For example, some of them go from minus 20 up to 550, and then some goes from minus 40 up to 550, and then some goes from minus 40 up to 1100 degrees Celsius, so it can range.
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There's a big range that they can visualize and observe.
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But it's not like they cap at 100 degrees, right.
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No, no, no.
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And also to get utility.
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You don't need it to be beyond the fire range, right, no right?
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to get utility, you don't need it to be beyond the fire range, right?
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No, right, I mean, you just need it to be able to operate within the expected conditions that you want to go into.
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And, if you think about it, I guess the expected condition is not necessarily a fully flashed over fire.
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Like what kind of information does a firefighter get from a camera?
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Right, it's like if you have a fully flashed over fire in front of your face, you don't need to have a thermal camera to confirm that Exactly.
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Okay, let's move on into how thermal cameras work.
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So perhaps there's a bit of interesting technical knowledge.
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So if you could briefly explain to me why my camera in a phone does not capture the temperatures and why this specific piece of equipment does, so we can go into some of the basics.
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I think if you want to go into the diesel and stuff.
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It might be like a full episode in itself.
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But I guess the idea is that you have different spectrums, electromagnetic spectrum, different regions that you want to observe.
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So you have the visible spectrum, which is 380 up to 780 nanometers, but then the infrared is also partitioned into different regions.
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But for long wave infrared cameras the range is 7 microns or 7 micrometers up to 14 approximately.
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So it's a very different range that they observe.
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So we have larger wavelengths, so the individual detectors also needs to be bigger.
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So if you have a standard digital camera, for example, it has a much higher resolution because also it's a different technology.
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So there's also been a lot of research in that specific field, compared to thermal cameras, which is normally used by the military, for example, if you want to go into building inspections, fire service but there's a lot of more utility necessarily for this common person with a camera.
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So the main thing is also the technology used, which is why you lower frame rates, lower resolution, but that's due to some of the physics involved.
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How can the thermal camera distinguish between temperatures?
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Actually?
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How does it know a thing is at a low temperature?
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How does it know that the thing is at a high temperature?
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So thermal imaging cameras works on the principle that if you have any objects in front of you, it will emit a certain amount of radiation Right, and then if you have an object that's of higher temperature, it's going to emit more radiation, which is then detected by this thermal imaging camera, meaning that you can discern two different objects of two different temperatures based on the one based, because they emit different amounts of radiation that is then detected by the detector in the thermal imaging camera.
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Okay, I can understand how we can observe walls and solid objects with thermal cameras.
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What about gases like in observing flames and smoke, etc.
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Because I know it's not a trivial thing, about gases like in observing flames and smoke, etc.
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Because I know it's not a trivial thing.
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So how much smoke do you see on a thermal camera?
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How much flame do you see in a thermal camera?
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What do you exactly see?
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You have to be right, it's not trivial.
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It's a lot easier to detect a wall, an object, something, especially if you want to have accurate gas phase temperatures off a flame.
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Very difficult to do.
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But I guess the main principle and why this thermal imaging camera is of utility to a firefighter is because that they operate in the range of 7 to 14 microns, because if you look at some of the combustion gases that is present during a fire, you know If you look at the absorbance, they have a large range where they have very low or no absorbance in that specific range, meaning that they're not going to obscure the image that you're trying to see.
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So you can see true smoke because of the gases' absorbance.
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So, for example, I used a thermal camera, for example, to make some videos of a small pool fire.
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I can see that because it still has radiation, blackbody radiation, so I can still see the flame.
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But if I want to visualize the combustion gases and it's not necessarily super, they don't have a lot of absorbance in the specific region or the spectrum of the longwave infrared camera then I can go down and use a midwave infrared camera so I can visualize the combustion gases more clearly, meaning that I can actually see it fairly clearly, even though it's not necessarily super visible to my eye.
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So also flames, for example, I used a midwave infrared camera to then make videos of a pool fire and then you can also see.
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So it was a visible flame, so it was a heptane, so it also has some soot, but then you can also very clearly see the flame and different flame structures and then also some of the combustion gases even above the flame.
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Can you define mid-wave?
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What spectrum would that be?
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Is it below seven?
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It is, so I guess it also depends on who you ask.
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I've seen different things one to five or three to five.
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I think the one that I would choose is probably three to five microns.
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So in essence, the ones that would be used by the fire service let's say seven to 14 default range, basically the stuff that the fire produces in abundance CO, co2, is transparent to those radiations.
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Therefore you can see better through them because you're not obscured by a large amount of radiation produced by those hot gases and at the same time it makes it difficult to observe those structures because basically they're transparent as well.
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So it's kind of a blessing and an issue depends on on on how you look on the problem.
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I I had an interesting episode on on observing through flames with matt hayler from from this.
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So yeah, we've been talking about blue light technology, so they've also found a way to to go very near uv radiation, where UV radiation, where the flame is almost transparent to that particular blue light wavelength and you can see through flames and, yes, it actually works like that.
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So, in essence, a very similar principle in here.
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So how much you need to know to?
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So let's imagine you're taking a picture with a thermal camera.
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It gives you some output.
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It's a simple device.
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It looks on photons, accumulates them, gives you an outcome.
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But what exactly?
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You have to know about the object you're observing to understand the values that you are seeing on your screen, for example, the emissivity of the surface that you are seeing on your screen.
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For example, the emissivity of the surface that you're observing with thermal camera.
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Do you need to know the emissivity, the reflectance of the surface that you're measuring?
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As you mentioned, there's a few different things that you need to know, but I guess this also depends on the purpose of what you want to do.
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Do you want to have accurate gas-based measurements?
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Do you want to have accurate measurements of the temperature of some solid object, which might be very valuable?
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But if you don't need that, if you just want to, let's say, identify hotspots, identify heat losses of a building, for example, which is also a common use of thermal cameras, you can do that without getting all of the different specifications correct.
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So, for example, the emissivity, distance to the object and so on, and also ambient temperature conditions.
00:22:33.298 --> 00:22:45.277
If you need to have accurate measurements of some phenomena, let's say gas phase or sonded phase, then you need a bit more information on what to do correctly, for example the emissivity.
00:22:45.277 --> 00:22:54.698
But as far as I know, the getting accurate gas phase measurements of a flame and then fully resolve it is very difficult.
00:22:54.698 --> 00:22:56.577
It's not so straightforward.
00:22:57.059 --> 00:23:03.994
Well, technically, if you take a camera and point it towards the flame, it will tell you like 600 degrees.
00:23:03.994 --> 00:23:08.776
It's not a flame temperature of any way, so it must be incorrect.
00:23:08.776 --> 00:23:16.996
But then I, a long time before COVID, we were doing some facades within pre-rule and we were observing.
00:23:16.996 --> 00:23:23.061
We had a steel facade, one that you actually the next generation of which is sold in the summer school.
00:23:23.061 --> 00:23:28.836
We had a prototype of that Long, long time ago and we had the steel plate.
00:23:28.930 --> 00:23:34.619
There was a fire in the cavity in the steel plate and basically we were taking pictures of this facade.
00:23:34.619 --> 00:23:53.118
It was giving us a very weird numbers and we had a black spray paint which was meant for chimneys, like literally black, very dark, very matte spray paint, and we were painting on that steel facade and the locations in which we painted it it's very black.
00:23:53.118 --> 00:24:01.038
The temperature measurements in that location were like almost one degree accurate with the thermocouple measurement in the same location.
00:24:01.038 --> 00:24:18.086
So because we, like you, could very well approximate emissivity of a matte black paint, which is very, very high, whereas for the steel surface that is undergoing heating and a lot of crystal formation transitions, it changes colors, it bends a little bit, it reflects less.
00:24:18.086 --> 00:24:18.569
In this location.
00:24:18.569 --> 00:24:20.576
It was a mess.
00:24:20.576 --> 00:24:27.604
So that was a moment when I realized I really need good control over what I'm measuring.
00:24:27.604 --> 00:24:35.678
I think the word measure in here is the key, because if you want to measure, you have to put in the effort to measure.
00:24:36.380 --> 00:24:50.175
If you're just observing, here you go, you're welcome to to see the range I think it's a great distinction to have either measure or observe, because for a lot of different things that you want to do with a thermal imaging camera, observations are just fine, right.
00:24:50.175 --> 00:24:54.356
You don't need to have very accurate temperatures, you just need to discern some difference.
00:24:54.356 --> 00:24:56.184
Maybe it's hot, maybe it's cold.
00:24:56.184 --> 00:24:57.691
If it's heat losses or whatever for building.
00:24:57.691 --> 00:25:07.393
If you want to measure, you have to take a lot more care into what you're doing, control the emissaries and do one of the steps to get accurate temperatures if that's what you want to do.
00:25:07.393 --> 00:25:18.296
But I think both observation and measurement has a place in fire safety science and what we used to do with it, especially if you're trying to do smoke and fire phenomena.
00:25:19.009 --> 00:25:21.098
There is this thing called optical thickness.
00:25:21.098 --> 00:25:26.900
Basically, the emissivity of a smoke layer is not just a physical function of the suit inside.
00:25:26.900 --> 00:25:33.816
It's about how deep the layer is until you reach the optical thickness and then it looks black.
00:25:33.816 --> 00:25:53.256
And if you don't know how thick the layer is, you cannot even tell how much smoke is in the layer, because you don't know if it's like very thin but very optically thick, or it's just a little smoke spread over 10 meters which will look to you in a similar way from the emissivity of a layer standpoint.
00:25:53.256 --> 00:25:56.521
So there's a lot of cave-ins.
00:25:56.722 --> 00:26:13.509
So in the end in fires I don't think the firefighters should trust the number they see on the camera, but I think they are very well advised to trust if something is hot or not in relationship to the surroundings.
00:26:13.509 --> 00:26:21.944
If I had to give a guidance to my firefighting colleagues, who definitely are professionals in using those devices they train.
00:26:21.944 --> 00:26:40.540
But my observation as a researcher using tools like that is that wow, so hard to get an accurate measurement, but it's, it's super easy to just, you know, get an overview absolutely yeah, and I think that's also valuable to know as a firefighter, like what to do with this should I trust the temperature or not?
00:26:40.840 --> 00:26:42.613
because I also heard from a firefighter.
00:26:42.613 --> 00:26:48.452
It was in europe, but he said that they didn't have so much money to get thermal imaging cameras.
00:26:48.452 --> 00:27:06.753
So they had, I think, one good thermal imaging camera, which was for the chief, I believe and then they had cheaper thermal imaging cameras still very useful because, as you say, you can still observe information and get a lot of valuable information even though you don't have the highest resolution or you haven't, you don't have the highest frame rate at all.
00:27:06.753 --> 00:27:08.439
Still are useful too, even though you don't have the highest frame rate at all.
00:27:08.439 --> 00:27:11.750
Still are useful too, even though you don't have the newest of the new or the best of the best.
00:27:12.430 --> 00:27:16.622
Are there big differences between particular cameras?
00:27:16.622 --> 00:27:22.819
How sensitive are they to the radiation of hot objects or gases in fires?
00:27:22.819 --> 00:27:31.640
Anything like any practical differences, or you can qualify all of them as, let's say, useful for fire and that's it.
00:27:31.640 --> 00:27:33.323
No, no big differences among them.
00:27:34.044 --> 00:27:34.284
Right.
00:27:34.284 --> 00:27:46.540
Different cameras of course, made by different manufacturers, will also have differences in quality service.
00:27:46.540 --> 00:27:50.210
The ones that are certified by the NFPA standard.
00:27:50.210 --> 00:28:05.604
They primarily use two different detector technologies, so one called vanadium oxide and one called amorphous silicon, and I think at some point I believe VOX of vanadium oxide was more prevalent on the market.
00:28:05.604 --> 00:28:16.714
But I think amorphous silicon as a detector technology also caught up and is also now part of the majority on the NFPA certified thermal imaging camera list.
00:28:16.714 --> 00:28:26.978
So there's definitely different materials used and they also have different material properties that also make some slight changes for the thermal imaging camera.
00:28:26.978 --> 00:28:33.079
But I think to a large degree thermal imaging cameras that are then certified by the NFPA.
00:28:33.079 --> 00:28:34.663
They have to go through the same test.
00:28:34.663 --> 00:28:41.920
So even though it's a difference, they take the technology.
00:28:41.920 --> 00:28:43.789
It should also still be very much of a utility to the fire service.
00:28:44.250 --> 00:28:50.903
And Hjulje, I guess, get to the point of the research grant and the research question that you were involved in.