How Does LiDAR Remote Sensing Work? Light Detection and Ranging

[@BMJSpectre1962]

As a geoscientist working a lot with ALS I commend this video so much. Most of our highly demanding clients that have stolen our specs have no idea. And yes, I had a client asking why do we joke so much about Emu's. Yes, we are in Australia!

[@NEONScience]

Glad you found the video useful! Go Emus!!!

[@waterboy12342232]

These and other instructional/educational videos are crucial. We need more of this on the internet. I work in the GEOINT field and find this to be the most comprehensive instructional piece to explain LiDAR to my subordinates and leadership.

[@NEONScience]

Chuck -- thank you for the kind words. We agree -- videos like these are important to helping people understand these technologies and the wide variety of sciences that remote sensing and lidar underpin. Glad to hear that it is useful to you. We are regularly adding move videos to the NEONScience channel. Not all will be remote sensing/lidar focused but they may still be of interest to you.

[@Indiana_drones0]

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[@peterburgess5974]

I am a layman, but LIDAR has helped define the route of a Roman road near my home. It is amazing technology and as a geographer it is brilliant in revealing morphology of the landscape which is virtually imperceptible to the human eye. Power to you!

[@sharicriddle8196]

Thank you! What a great introduction for fourth grade students!

[@chainsawvsgod384]

Excellent video. Explained it really well. I'll use what I've learnt here for my upcoming exam.

[@NEONScience]

Glad it was useful!

[@qcjefftqc]

This is great! I've been doing research in LiDAR for a while and i'll probably point people to this video when they want to know what the hell I do ahah!!

[@NEONScience]

I'm so glad you found this video useful! It is nice to have a short visual when explaining our research!

[@amanuelbeyin3063]

Very helpful.....Thanks NEON. The narrator was terrific.

[@NEONScience]

+Amanuel Beyin we are glad that you enjoyed the video! thank you for the positive feedback!

[@043mehdi]

no, she's sexy. Come on bro

[@SalakoIshola]

Great teaching on LiDAR introduction

[@hmnaik]

Its a good video, sticking to basics and keeping it simple.

[@Indiana_drones0]

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[@1992danceboy]

Lolo! Very entertaining and informative video on LiDAR! Always wondered what the heck it was and this video did the job great and with jokes! May take a remote sensing class now :O

[@Indiana_drones0]

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[@aronricardovideo]

Excelente, y gracias también por la traducción a español! Hacen un trabajo impresionante!

[@Indiana_drones0]

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[@Indiana_drones0]

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[@imtiazhimel7339]

Extremely helpful. And very nice presentation.

[@brianarmadan7333]

Very informative, however I noticed an issue with the visualization at ~1:34. The satellites should be in the center of the circles that intersect the airplane. Technically they should be spheres, but circles are sufficient for conceptual purposes.

[@NEONScience]

Thank you for adding the excellent point of clarification. We did simply the graphic to just show the points of intersection on a circle, not the sphere.

[@fidget2020]

Nice video, but I have one nit-picker and that is that the IMU does not measure or track the planes position (Part 3 of the system, around 1:52) it measures the orientation or attitude of the aircraft.

[@Indiana_drones0]

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[@ΔΗΜΗΤΡΙΟΣΚΑΝΕΛΛΟΠΟΥΛΟΣ-ρ7σ]

an excellent way to explain using humor, BRAVO

[@MaxWaster]

Helped me for my archaeology essay!

[@majharshaikh3483]

its too good 😍😍 after seeing this video i am so excited for this system. Good Job

[@richardryan7062]

Great presentation! 👍

[@getreadytotube]

awesome explanation. Thanks!

[@advancedgeographicinformat8561]

This was a great educational video that our company will use to help educate our future employees for further growth and development, keep up the great work, you guys just got a subscriber!!!!!!!!!!!!!!!!!!

[@NEONScience]

Excellent! We're glad it is useful.

[@viannyahimbisibwe2757]

yeah well done. Am looking forward to learning more with using remote sensing in ecosystem management

[@dl8cy]

thank you for using CC licenz for that great video!

[@jessif.]

Thanks so much for this clear explanation!

[@tymothylim6550]

Wow! Great video. Thank you!

[@torrieallen6137]

This is a great video. I have watched it many times over the last 8 months for college and each time I pick up some little detail I didn't remember from the last time I watched it. Very good Video. Thank you. Thank you also for going into the pulse return a little deeper in the comments section, I too was wondering about that as well. Thank you again.

[@NEONScience]

Torrie - I'm so glad the video was useful for you.

[@woody000555]

Great presentation, thanks!

[@adisuryanathanael6056]

Firstly thank you for this useful info. can LiDAR detect fire flame? need your advice. Thank you

[@NEONScience]

Interesting question! LiDAR can be used to detect fires but the detection is actually based on the smoke, not the flame (see reference here: journals.sagepub.com/doi/full/10.1155/2014/597368). The laser needs an object to bounce back from.

[@AnilKumar-xl2te]

Great explanation

[@Indiana_drones0]

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[@Trending_Topics-us4mn]

Very helpful

[@jacobboomsma2341]

Great and helpful video. The emu joke was cringe, but actually extremely useful, as I will remember IMU for my exam tomorrow! Thanks :)

[@NEONScience]

Glad you found it useful. Hope you do great on the exam!

[@maelyorn1840]

I seriously love the video. Amazing teaching. Thank you so much.

[@Indiana_drones0]

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[@hanasoualahalila2333]

Exellent presentation, Bravo, we need more video to share to help students Thanks

[@NEONScience]

Feel free to share with other students! Glad you found it useful.

[@grahamjoss4643]

Thanks for sharing!

[@VHS_GIS]

I loved your EMU!!! GO GO EMU!

[@naveenpgeo]

Nicely explained the working method of LiDAR. Good for initial knowledge. Thanks.

[@NEONScience]

Glad you found it useful.

[@self.improved]

Very informative, thank you for taking the time to make this video!

[@NEONScience]

Thank you! Glad you found it useful.

[@thinkandlearn7258]

great Video

[@mikael5743]

awesome animation and presentation

[@rudra9506]

awesome video!!! graphics and narration are good :)

[@NEONScience]

+uday sen pendiala Thank you - we are glad you enjoyed it!

[@Mishra11raj]

Beautifully created content, so satisfied to see such real good one. Good job. Loved it

[@Indiana_drones0]

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[@maybeclaire4738]

Very interesting.

[@melaniamonicacraciun9900]

It might read the landslides as well as earthquakes areas on jeopardy fans, think about it, what a great discovery. Being ready to prevent natural disasters we are never prepaired enough to save lives, a great thing indeed

[@mesfin_bikilo]

Nicely presented !!

[@kelennaanyanwu5372]

Very well explained. Thanks a lot

[@NEONScience]

Thanks for the feedback. Glad it helped.

[@andreadanniballe5013]

Great explanation!

[@MarcosSpinelli]

Great Video! Thanks.

[@NEONScience]

+Marcos Spinelli glad you enjoyed it!

[@kcoo4115]

Well done. Thanks. Now looking for the video that explains how LiDAR is used to map forests. My interest. Also interested in when free LiDAR will be available and where to find it.

[@mgamga]

Good Video.

[@shibinwang1879]

Thanks for uploading.

[@NEONScience]

of course! we are glad that you enjoyed it!

[@ywk7282]

Thanks for the video. I have one question. How do we assure that the light comes back? Isnt it possible for the light to reflect and not come back to the lidar!

[@Indiana_drones0]

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[@1nZaneR]

didn't know I had friends until I watched that video!

[@1nZaneR]

@mr.1n5an_e dang shame you are a Mr. ;-)

[@GinoFoto]

Very useful and easy to understand basic of technology. LIKE

[@Indiana_drones0]

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[@PraveenYadav-wo1ig]

Great Video, Could you please share tools you used to make video

[@NEONScience]

+Praveen Singh Hi Praveen - We use Adobe After effects mostly! Although we record using audition.

[@shadowfox_117]

Great video very informative.

[@NEONScience]

Thank you for the feedback. Glad you found the information useful!

[@alfredojavier59]

excellent video

[@NEONScience]

Thanks!

[@rameshpraveen5929]

Wow, Nice Video, I have 8-year experience in Lidar classification but still, I can't explain lidar like this. I really love this way of explanation :-)

[@NEONScience]

Thank you!

[@cherylcurrid6508]

Excellent

[@NEONScience]

Thank you.

[@zeu_stek]

LiDAR is genius for a horror game

[@SusanMahatara-ik5nq]

Aweosme work !

[@mrnohax5436]

was that guitar riff from satisfaction - rolling stones

[@ekremvkilic]

"I am you", kinda romatic :)

[@lamfmhn95]

Very informative and beautiful vid :> Thanks!

[@NEONScience]

+Tùng Lâm Nguyễn Glad you enjoyed the video! thank you for the feedback!

[@KulbirAhluwalia]

Awesome animations! Well explained! This video accomplishes the complex task of connecting with the masses. Lol

[@geomagazine_khalid]

PDF Book: Image Processing & GIS for Remote Sensing: kzbin.info/www/bejne/e5zamn2dZbeMeaM

[@pierre-oliviergagnon3706]

Did you make the video about the forest structure?

[@NEONScience]

Hi. Unfortunately, I'm not sure which "forest structure" video you are referring to. All of our animated science videos can be found in this playlist: kzbin.info/aero/PLLWiknuNGd50GI8OZf3EBo6PMx04xcoFa

[@tenlyrodrigues8138]

Really useful to understand the basics of LIDAR.- Thank you

[@moni2637]

Thanks just cleared the basic concept

[@Indiana_drones0]

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[@geogeekthetechguys5091]

great and really helpful

[@NEONScience]

Thanks. Glad you found it useful.

[@atharvadeshpande9782]

good video. keep it up

[@NEONScience]

+Atharva Deshpande thank you - we are glad you enjoyed the video

[@NYNCoaching]

Hello, how interesting video it is! I really want to know how to estimate forest structure but i can't find it out in your videos. Have you been posted or not yet? Please...... I'm very interested in the next steps. Many thanks.

[@NEONScience]

Hi. There are many different ways to estimate the structure of a forest. Are you interested in heterogeneity of tree heights, the biomass of trees in a given area, layers of canopy, etc. We don't have a video specifically about these topics. However, we do offer some tutorials for calculating some of the parameters that go into these questions on our website: www.neonscience.org/resources/data-tutorials

[@YewWonda]

nice video. can anyone tell me what the grund elevation is and why we take the 2024m (Why??) - distance (1000??? WHY where do i get this from) (at: 3:54.) Why do we do this calculation? Thanks a lot.!!

[@NEONScience]

Hi. In the case outlined in this part of the video, the unnamed scientists are trying to precisely measure the elevation of the ground (and any trees or building). To do this with the laser, we have to know several things: 1) Accurate height of the plane (in the video: 2024m, obtained from a GPS onboard the plane) and 2) the distance the laser pulse travelled from the ground to the plane (in the video: 1000m, obtained from the time the light took to travel from plane to ground and back to plane). Both of the numbers (2024m and 1000m ) are examples and would likely vary by every point taken. Does this clarify the video? If not, feel free to ask. --Thank you.

[@Junnarshivray]

That was amazing ..! May i get LiDAR data for vegetation cover in Himalayas? And can we broadly identify the type of forest from such data?

[@NEONScience]

Pranav Hirave hi there!! we are glad you enjoyed the video! good question. there are lidar data available for various parts of the world however you'd have to search in that region to figure out if data have been flown for the areas your interested in. It's can be pricey to collect so larger collections are a bit more rare in many parts of the world. Lidar has been used to identify conifer vs deciduous over larger areas. But it's more effective if you combine lidar with imagery to get into species mapping. lots of options however! thank you for your comment and good luck with your project!! :)

[@Junnarshivray]

Yeah thanks to you too..! I would definitely search for such data repository

[@mesfin_bikilo]

It is really amazing i like it very much i have been looking for such technology that makes life easy and cost effective for my research work and my life as well.

[@alphaapple1375]

Lidar is nowadays a common noun that people do not bother capitalizing it, similar to Laser, Maser, Radar, and Sonar which were originally acronyms for "Light Amplification by Stimulated Emission of Radiation", "Microwave Amplification by Stimulated Emission of Radiation", "Radio Detection And Ranging" or "Radio Direction And Ranging", and "SOund Navigation And Ranging".

[@NEONScience]

Agreed. There has definitely been a shift over the last 5 or so years.

[@Tshozyn]

thank you soo much... very useful :)

[@Indiana_drones0]

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[@F3ND1MUS]

cool video!

[@Jousieshipepe]

good video indeed

[@marcdeni8555]

THIS COULD BE THE START OF "DETECTNOLOGY"

[@silverhawk923]

What’s that?

[@gm130s]

Thanks so much for such a well articulated video!! Kudos to (multiple) appearance of EMU. Made me giggle. One suggestion: Including GPU + IMU as a required Lidar system components might be confusing (GPU + IMU are useful when Lidar is used for getting posisions and poses of target objects) ?

[@Indiana_drones0]

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[@hongbinbin24]

excellent

[@NEONScience]

Thank you! Glad you found it useful.

[@walterharoldbishop]

in short : lidar uses light and measures distance. very informative.

[@kimbott4963]

Honestly this had more information than any of the so-called lectures I've looked at. Those all took 15 minutes to be like "and radar uses radio" ok dude great. At least this mentioned the IMU, and some of the subtlety of difficulties in measuring, and talked about how the measurement is made (maybe you missed it judging from your "summary" there). This channel I think is for general audiences so it's actually pretty impressive they got through so much while some person meant to give an hour long lecture can't even get around to wavelength choice or location and movement considerations.

[@asifadam93]

Great video Thanks

[@stevecampbell5314]

Thanks!

[@EddieAiello]

Such a great video! Thank you. Would you please recommend some extra reading or other sources where I could learn more about LIDAR and get more involved with it?

[@NEONScience]

Eddie Aiello Hi Eddie! we are glad you enjoyed the video! there are a lot of great resources out there to learn more. For instance, in the past year Penn State has put many of their course materials online! www.worldcampus.psu.edu/RS so you can read through their materials. they have an entire section on lidar as well in there and some other courses in imagery. i'd start there!:) another older tutorial was produced by NASA years ago. I found a copy of it here www.fas.org/irp/imint/docs/rst/Front/tofc.html ... the formatting visually is a bit dated by the information is solid and provides a good general foundation. i'm sure there are others as well but these two have a lot of content to go through that you might enjoy! Cheers!

[@EddieAiello]

Thank you so much for all the great info! I can't wait for some more great videos from you...

[@albertodacruztinta6074]

To the girl who narrated this video, awsome job, with the jokes and all.

[@douglaslane6184]

And now these are in our cell phones

[@shadrackchirchir1484]

just stunning

[@paulendry6398]

If hair on an old man’s back makes the narrator go ‘oowh’ then don’t show it

[@JD-kf2ki]

What's the difference between the altitude and distance in this case?

[@NEONScience]

As referred to in the video, altitude is the elevation of the plane above sea level. The distance we refer to is the elevation of the plane, in relation to the ground directly below it.

[@doctorofart]

What is the resolution of LIDAR. Would this be good technology to map a boulder train that extends over 20 miles and is between 100 and 300 yards wide. How expensive is it to have done? Are there companies that provide this service for private parties? TY

[@NEONScience]

NEON Associate Scientist Tristan Goulden offers these comments on your questions: The ‘resolution’ of LiDAR can vary depending on the type of sensor and platform. Typically airborne LiDAR surveys with fixed wing aircraft can normally achieve 5 - 10 points per square meter with the most recent sensors. Using a helicopter, the point density can be increased due to the ability to fly at lower altitudes and speeds, however this comes at an increased cost. Using a helicopter point densities up to 50 points per square meter are not uncommon. The most dense LiDAR surveys can be acquired through terrestrial laser scanners. These are stationary systems that scan from the ground. The point density from these systems can be as high as the user desires, typically achieving hundreds of points per square meter. However, it takes much longer to cover a large area than an airborne survey. Raw LiDAR data is termed a ‘point cloud’, and point density is often used as a metric as opposed to resolution. Once the LiDAR point cloud is ‘gridded’ into a raster product such as a DTM or DEM, resolution is a more common term. LiDAR rasters are typically created at twice the nominal point density. For example, if your point cloud achieves two points per square meter, you should only create a raster product with a resolution of 1 meter. Yes, LiDAR is a good technology to map a boulder train of that size with an airborne survey or terrestrial survey being options. A terrestrial laser scanner will take a lot of time for an area that size, however may be cheaper. An airborne survey of the area that size would be quick, but incurs significant overhead in deploying an aircraft so costs come down significantly as the size of the area increases. Exact costs are highly dependent on the area, type of sensor and aircraft desired, or time required for a terrestrial scan. There are several remote sensing and land surveying companies that will provide these services for private parties and would be able to provide reliable costs estimates. -- NEON's Assignable Assets program (www.neonscience.org/assignable-assets) will include airborne LiDAR capabilities.

[@maheshmurali2063]

👍👍👍

[@97Alfinsyah]

I wish i could reach my dreams school at Remote Sensing Chiba University Japan. Thanks for knowledge and sharing this video

[@NEONScience]

You 're welcome. Glad the information was useful.

[@monuanurag11]

Nice video. I have one doubt, if the laser light is sent to a flat ground from certain height at an angle say theta from normal to the ground how come the receivers receive the ray back? Shouldn't it travel with theta angle normal to the ground in other direction?

[@NEONScience]

Anurag Dixt - great question. And yes, if the ground was utterly, perfectly flat that is true. However, given that all objects are less than ideally smooth when the laser hits the ground the light scatters and some of it does bounce back at the receivers.

[@renatosabato]

Quick question: how come light reflects exactly in the direciont of where it came from? What if it does not?

[@randombits2620]

What if light from sun is reflected to receiver

[@NEONScience]

Thanks for checking out the vid, and good question! Yes, it is possible that the receiver will detect reflected solar radiation. Typically the signal from reflected solar energy is much lower than the energy from the returned laser pulse so the added noise is negligible. However, there are instances such as specular reflection from water, where reflected solar energy can trigger a false return. Normally these returns can be easily identified and flagged as noise.

[@tiemomerkel6113]

great video :-)

[@Alex-pp4wj]

I have a question - how does it always return emitted laser pulse back to the plane? - How can we guarantee the needed angle? What if the surface just reflects it to another direction?

[@hhzmaung]

Amazing

[@abdulziyan6591]

Can it be used to detect flooded potholes. Will it get reflect from the water surface ?

[@Indiana_drones0]

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[@dustinbaze]

Does it require an atomic clock? How does it get a precise measurement of the time it takes for the pulse to bounce back? Light can travel around the world 7 times in a second. The time between the pulse and the return must be incredibly small.

[@NEONScience]

+D Bay This is a fantastic question. We consulted with NEON Airborne Observation Platform Staff Scientists on this question! Here is your answer - the lidar does not need an atomic clock - please read below. ``````````````````````` Great question! Yes, the time between transmission and reception is incredibly small. We do not require an atomic clock, those are in GPS satellites and are required for very accurate and precise absolute time. We do not need absolute time in the LIDAR systems, only relative time (the time it takes for the pulse to travel to the ground and back). Calculating this time can be achieved with less expensive solutions than atomic clocks. The clocks in the waveform digitizers for both the Riegl and Optech sensors (the ones we are using) are capable of measuring to a precision of 1 nano second. Given a pulse travels ~0.15 m in a nano second, this is sufficient resolution to accurately measure travel time and in turn calculate distance. ```````````` We hope that this answers your question!

[@benjaminalawani7267]

GPS time or UTM and is atomic. Yes the time is incredibly small but can be measured all the same. A technology called DGPS is already being used to measure positions to 1m accuracy and even less if need be. The question to ask though is the possible smearing of the data since the plane is not stationary. That is the place will have moved some distance before the reflected light returns. But again this may be insignificant compared to the speed of light and for small elevations.

[@faustin289]

Since the height calculation involves the time the pulse leaves and returns at awfully high precision, I'd expect a good clock (preferably an atomic one) to be part of a LiDAR system.

[@Alex-pp4wj]

Good point! Also I have a question - how does it always return emitted laser pulse back to the plane? - How can we guarantee the needed angle? What if the surface just reflects it to another direction?

[@s1ight]

you're right each pulse has a carrier phase signature associated with it, no clock can measure such a fast return but it can record when the individual pulse leaves and then later calculate when that distinct pulse returned

[@vizspectator]

I had a question, so LIDAR sensors can register only one point on ground surface at one time? If not how does the LIDAR sensor differentiate between multiple reflected pulses at one instance of time?

[@NEONScience]

+gurminder bharani We went to the scientists with our Aerial Observation Platform to get a complete answer for you. *** The LiDAR sensor measures the return time of the laser pulse to calculate a range. If there are multiple objects in the optical path of the laser beam, such as vegetation, they can be differentiated and can create multiple returns. The sensor used by Optech can differentiate up to 4 returns. The range resolution of the sensor defines a minimum separation distance of objects which allows multiple distinct returns. The sensor operated by NEON has a range resolution of approximately 2 m, meaning objects less than two meters apart cannot be differentiated. The range resolution is dependent on the outgoing pulse width of the laser pulse, which is ~10 ns on the NEON LiDAR sensor. Object greater than 2 m will have returns separated by approximately 10 ns. Although we conceptually think about a beam of laser light being ‘instantaneous’ in time, the timing systems on the LiDAR sensor are precise enough to measure extremely small differences in the return time (down to 1 ns).”

[@2jpu524]

This is a question of the design with both the software and hardware. You can indeed see multiple returns from the same laser pulse. The laser diverges with distance, and will hit multiple objects, like leaves in a tree, before hitting something like a wall. With each hit, there is a chance you'll get a reasonable return. This quickly however falls into the domain of "signal detection theory". Often multiple return data has varying return intensities, where the return is compared against the ratio of the signal+noise to the noise estimate (see ROC curves). It can be challenging to maintain a "constant false alarm rate" with the strongest return. It becomes trickier to decide on which is signal and which is noise for the weaker returns. The return pulses always have some degree of shot and thermal noise.. I did this for a living for a time.. there are a lot of subtleties that make lidar an interesting problem.

[@NEONScience]

Great point. Yes, the video does simplify the process considerably!

[@biIIybob858]

Gmod?