Turns out you can't add a link at the end of a video with less than 1k subscribers :') So please subscribe, and here's the Patreon link. Not as fun as clicking on my face but it would help just as much! www.patreon.com/mindsbehindmaps Also, some mistakes spotted by viewers: - All the early animations explaining the basics of radar have a typo in them: It's "Received Energy", not "Recieved". This one's painful because it appears so many times - 7:43 has another typo, "Synthetic" Aperture Radar. Thanks to everyone for keeping me accountable and pointing these errors out!
Great video and great timing as I'm writing up my dissertation, subscribed! One note though: in the "Basics of Radar" section it should be "receive" and not "recieve."
@@MaxLenormand I saw that too, and I think it makes it even better. It shows you did the figures. It is the imperfections that bring the sense of scale of the effort :)
People running these teams should consider getting a radiologist on board. Radiologist live and breath analyzing information like this. They might make valuable contribution to testing these kind of approaches
Really great explanation Maxime! The most comprehensive (and entertaining) video on the subject of SAR. This should be essential viewing for anyone getting into Earth Observation.
SAR can see into buildings the same way when you bounce a ball under a table and strike the underside of the table, the ball bounces back to where it was thrown, never through the table. If a building has an opening wide enough the microwaves can bounce back out the opening and return an image of what was inside. Think like a jet in a hangar.
That's true! Different wave lengths also have different penetration properties, so some can go through very thin roofs to see below, there are some examples of seeing planes through hangars in SAR. I made the choice of not talking about different bands to keep it short. And that Capella blog post just makes me laugh
Strictly speaking, the aperture of a lens is the ratio between the lens opening and the focal length, instead of it being the size of a lens. The smaller the ratio between focal length and aperture (f number), the closer the two are together and the more light can hit the sensor. Numbers below f/1 mean, that the aperture opening is larger than the focal length. Going back to SAR, you can imagine that by moving the radar satellite around while looking at the same object is similar to opening the aperture of a lens (like going from f/11 to f/1.8 in the image at 9:30) more and more and letting more light in and thus increasing the Signal to Noise Ratio. With digital cameras, this means we get more detail and less noise and with SAR it means... the very same thing :D
Totally! I didn't do the best job of going from f/1 in optical -> SAR I also wanted to mostly convey the idea of why it's called "Synthetic Aperture" in a relatively short amount of time. That's why I like the fact people can comment on these videos, I get new ideas as to how to better tell these next time :)
Incredible video! 👏 I’m working on looking for a job in the space sector and SAR is something I’ve become fascinated by. I’ve read up on it a bit and started reading Thomas Ager’s “The Essentials of SAR.” Having explanations with visuals like this really helped to reinforce and unlock that knowledge. Thank you!
Muito obrigado por esta aula. Realmente, é contra intuitivo trabalhar com imagem de radar quando você trabalha com imagens ópticas há muito tempo. Parabéns a todos da sua equipe.
Personally, I'd explain SNR with sound. Let's say you have two speakers: one plays, let's say, an audiobook, and does so at a set volume that you never change. The second speaker plays white noise. Speaker #1 is your signal, speaker #2 is your noise. As speaker #2 gets louder, it's more and more difficult to understand the audiobook and at some point the signal is unusable because of the very high noise.
Hey, I'm learning SAR and this really helped. I think the only thing I'm still curious to get an intuition for is how they used SAR on film and lenses to do the "analog" computing of SAR images before computers had enough storage and compute to do what they do now.
Oh my, good catch... That's starting to be a lot of typos for a 23min video. I spent a lot of time trying to get the basics right, that I seem to have overlooked some of the polish here, apologies for that I'll try to do better next time!
Great explanation in the first half. But in the beginning the range is is just one pulse or bump. There is not any explanation, how the one pulse is suddenly many bumps i.e. pixels i.e. picture elements? This is not explained in other vbloggers presentations, so you are not the only. Also the sending perpendicularly is essential to present.
I decided not to really touch on that in depth because 1. I don't fully understand it myself and 2. it could have made this even longer, when I was trying to stick to a high level introduction I do suggest you check out Thomas Ager's book though if you want more in depth information!
Turns out you can't add a link at the end of a video with less than 1k subscribers :') So please subscribe, and here's the Patreon link. Not as fun as clicking on my face but it would help just as much! www.patreon.com/mindsbehindmaps
Also, some mistakes spotted by viewers:
- All the early animations explaining the basics of radar have a typo in them: It's "Received Energy", not "Recieved". This one's painful because it appears so many times
- 7:43 has another typo, "Synthetic" Aperture Radar.
Thanks to everyone for keeping me accountable and pointing these errors out!
Great video and great timing as I'm writing up my dissertation, subscribed! One note though: in the "Basics of Radar" section it should be "receive" and not "recieve."
@@EduardHeijkoopThank you!
Good catch, no matter how many times I rewatch these there's always a mistake!
Unfortunately I can't edit this in the video
@@MaxLenormand I saw that too, and I think it makes it even better. It shows you did the figures. It is the imperfections that bring the sense of scale of the effort :)
Man you really nailed this video! Everytime someone asks me about SAR from now on I'll be linking this to them. Looking forward to seeing more!
Thanks a lot Harry! My hope was to make a good reference for anyone wanting to learn more about SAR!
Exactly my train of thought after watching it!
People running these teams should consider getting a radiologist on board. Radiologist live and breath analyzing information like this. They might make valuable contribution to testing these kind of approaches
Really great explanation Maxime! The most comprehensive (and entertaining) video on the subject of SAR. This should be essential viewing for anyone getting into Earth Observation.
Great explanation on SAR, after working with geospatial data for 5 years I finally understand it now 😁
If anything I'm glad that's my contribution to the Earth Observation!
SAR can see into buildings the same way when you bounce a ball under a table and strike the underside of the table, the ball bounces back to where it was thrown, never through the table. If a building has an opening wide enough the microwaves can bounce back out the opening and return an image of what was inside. Think like a jet in a hangar.
That's true! Different wave lengths also have different penetration properties, so some can go through very thin roofs to see below, there are some examples of seeing planes through hangars in SAR. I made the choice of not talking about different bands to keep it short.
And that Capella blog post just makes me laugh
Strictly speaking, the aperture of a lens is the ratio between the lens opening and the focal length, instead of it being the size of a lens.
The smaller the ratio between focal length and aperture (f number), the closer the two are together and the more light can hit the sensor. Numbers below f/1 mean, that the aperture opening is larger than the focal length.
Going back to SAR, you can imagine that by moving the radar satellite around while looking at the same object is similar to opening the aperture of a lens (like going from f/11 to f/1.8 in the image at 9:30) more and more and letting more light in and thus increasing the Signal to Noise Ratio.
With digital cameras, this means we get more detail and less noise and with SAR it means... the very same thing :D
Totally! I didn't do the best job of going from f/1 in optical -> SAR
I also wanted to mostly convey the idea of why it's called "Synthetic Aperture" in a relatively short amount of time.
That's why I like the fact people can comment on these videos, I get new ideas as to how to better tell these next time :)
this video was so informative, thank you so much!
Incredible video quality, and learned so much about SAR
Thanks so much! And so glad if more people are learning about SAR!
Such a great video and explanation! Helps me in geodetic earth observation seminar at university:)
This video is way cooler than being able to download free SAR imagery through SkyFi!
Well, SkyFi helped the making of this video, had to have a way to find all the Umbra images!
Thanks for the video! Learned a few things I didn't know and this came just right as I begin working with the stuff.
Really glad to read it was helpful!
I am totally un-phase-d of your success Max, this is one heck of a content!
So many SAR puns out there ;)
Thanks a lot Thomas! I'm glad you liked this one!
Massively underrated channel and fantastic video. How do you not have at least 5k subs yet??
Thank you! Hopefully it's only a matter of time!
This really helped me understand SAR more! Thanks!
What a great Video! So well explained in such a short time! Thank you very much 💪
Incredible video! 👏 I’m working on looking for a job in the space sector and SAR is something I’ve become fascinated by. I’ve read up on it a bit and started reading Thomas Ager’s “The Essentials of SAR.” Having explanations with visuals like this really helped to reinforce and unlock that knowledge. Thank you!
What a great video, looking forward for the nexts ones.
Amazing ❤ thanks for that vidéo
Great video. Congrats
Thank you!
Thanks !!!
Great explanation. Learnt so much and now I see SAR in a different way ❤
Thank you!
Muito obrigado por esta aula. Realmente, é contra intuitivo trabalhar com imagem de radar quando você trabalha com imagens ópticas há muito tempo. Parabéns a todos da sua equipe.
I had to translate your message but it seems like this was helpful to you, for which I'm glad! Thanks for taking the time to write this!
Personally, I'd explain SNR with sound.
Let's say you have two speakers: one plays, let's say, an audiobook, and does so at a set volume that you never change. The second speaker plays white noise.
Speaker #1 is your signal, speaker #2 is your noise.
As speaker #2 gets louder, it's more and more difficult to understand the audiobook and at some point the signal is unusable because of the very high noise.
That's a good point! There are many ways to approach this, I wanted to keep it related to images though
Hey, I'm learning SAR and this really helped. I think the only thing I'm still curious to get an intuition for is how they used SAR on film and lenses to do the "analog" computing of SAR images before computers had enough storage and compute to do what they do now.
That’s actually a really good question, which I didn’t even think about
I have no idea!
Spotted a typo in Synthetic Aperture Radar, between 7 and 8 minutes 😉
Oh my, good catch...
That's starting to be a lot of typos for a 23min video. I spent a lot of time trying to get the basics right, that I seem to have overlooked some of the polish here, apologies for that
I'll try to do better next time!
Great explanation in the first half. But in the beginning the range is is just one pulse or bump. There is not any explanation, how the one pulse is suddenly many bumps i.e. pixels i.e. picture elements? This is not explained in other vbloggers presentations, so you are not the only.
Also the sending perpendicularly is essential to present.
When the satellite moves the angel of view will change too doesn't it effect on finial image and make it weird or unaccurate ?
I still can't understand what's the way that the synthetic aperture radar combine all independent picture together.
I decided not to really touch on that in depth because 1. I don't fully understand it myself and 2. it could have made this even longer, when I was trying to stick to a high level introduction
I do suggest you check out Thomas Ager's book though if you want more in depth information!
Why do modern men sound like Kermit The Frog?