Talk:Lidar

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Wiki Education Foundation-supported course assignment[edit]

This article was the subject of a Wiki Education Foundation-supported course assignment, between 15 January 2019 and 3 May 2019. Further details are available on the course page. Student editor(s): Justinvmaher, Zehracheatham.

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Wiki Education Foundation-supported course assignment[edit]

This article is or was the subject of a Wiki Education Foundation-supported course assignment. Further details are available on the course page. Student editor(s): Phantom2k10, Loganbarrett28, Gyutaek.c, Ghammack.

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Aren't radio waves light, technically?[edit]

Call me crazy, but aren't radio waves technically light as well? Thus it's hard to say that LIDAR uses light rather than radio waves... --Dante Alighieri 09:19 28 Jun 2003 (UTC)

Light and radio waves are both distinct forms of electromagnetic radiation. I don't think the definitions of light and radio waves overlap. The wavelength range of light is about 400 to 800 nm, while the range of radio waves is about 0.1 m to infinity. These ranges do not overlap. See Electromagnetic spectrum. -- Heron 09:31, 28 June 2003 (UTC)[reply]
Well, I'm not talking about visible light, but light as a generic term... used to refer to the entire electro-magnetic spectrum. If light refers only to visible light, then it seems rather redundant to call it visible light. ;) --Dante Alighieri 09:45 28 Jun 2003 (UTC)
Infra-red and ultra-violet are generally thought of as light too. Generally "light" is used to refer to anything between the far infra-red to the extreme ultra-violet. Terahertz radiation represents the grey area between "light" and radio at the low end, and EUV starts to blend into "soft" X-rays at the high end.
So it's:
  • Radio
    • ELF, VLF
    • ...
    • UHF
    • Microwaves
  • Terahertz rays (grey area)
  • Light
    • Far IR
    • Near IR
    • Visible spectrum
      • "Red, orange, yellow, green, blue, indigo, violet"
    • Ultra-violet
  • Extreme ultraviolet (grey area)
  • X-rays
  • Gamma rays
  • etc...
— Preceding unsigned comment added by 217.158.106.44 (talk) 10:03, 28 June 2003 (UTC)[reply]
(A comment by 131.107.0.102, 10 November 2009, was moved down to More on the definition of light below, due to the age of the above discussion.) --83.253.248.109 (talk) 13:49, 20 April 2010 (UTC)[reply]

Article name[edit]

Is LADAR the correct term here - or should it be LIDAR? Perhaps with a sub heading for Ladar.

  • Ladar also seems to have a lot of eye surgery references as there is a tradenamed procedure that begins with Ladar.
  • Also see Ladar which cross references to Lidar, as a more general term.
  • A google search for Ladar gives 9,160 entries, while a google search for Lidar gives 296,000.

Lidar is linked to Ladar in Wikipedia. I think it should be the other way around, or there should be two entries. Also should these terms be capitalised? They are spelt as Ladar and Lidar in many internet entries. Any thoughts? kiwiinapanic 09:59, 17 Dec 2003 (UTC)

I'm with you on this. I originally created this as an offshoot of RADAR and have since learned that it's much more common to refer to it as LIDAR. Feel free to move it! Maury 13:19, 17 Dec 2003 (UTC)

Page moved from LADAR to LIDAR. kiwiinapanic 11:37, 31 Dec 2003 (UTC)

Lidar is the more general term. The distinction between lidar and ladar depends more on the nature of the target. Traditionally lidar has been used to refer to diffuse targets (eg atmospheric aerosols) while ladar has been used to refer to hard (ie solid) targets. In the early 90s there was a letter submitted to Photonics Spectra (IIRC) that discussed the subtleties of this issue. Personally I tend to use the term laser remote sensing these days as not all of the instruments I develop in my professional life provide range information and lidar is therefore a subset of laser remote sensing. There are a number of implicit assumptions built into the information currently conveyed on the page that are not always correct. I will think about how to correct these with minimal editing changes but do not have time at the moment. --Gary Spiers - www.lidar.com — Preceding unsigned comment added by 66.159.192.247 (talk) 05:16, 28 April 2004 (UTC)[reply]

Mirror choice[edit]

Can anyone tell me what some of the pros & cons are of using a polygon mirror[1]? — Preceding unsigned comment added by 209.247.234.99 (talk) 15:13, 13 April 2004 (UTC)[reply]

Acronym[edit]

LADAR stands for LASER Detection and Ranging. LASER stands for Light Amplification by Stimulated Emission of Radiation. If you string the whole thing together, you get "Light Amplification by Stimulated Emission of Radiation, Detection, and Ranging." How do you emit detection and ranging? Same thing goes for LIDAR, except it emits imaging too. — Daniel 01:34, 21 December 2005 (UTC)[reply]

LASER in the name simply refers to the device which emits a coherent beam of light. LIDAR is simply Detection, Ranging and Imaging through the use of a scanning laser. Trying to work the LASER acronym open inside the LIDAR acronym is unnecessary. — Preceding unsigned comment added by 142.167.179.232 (talk) 10:32, 20 March 2006 (UTC)[reply]
I dimly recall that it was an acronym of Laser Interferometry Detection And Ranging. It was probably in a journal or newspaper. Or perhaps on Tomorrow's World, a BBCtv science-magazine program. It is an uncertain memory. Archolman (talk) 21:22, 9 August 2013 (UTC)[reply]

Cleanup[edit]

The style on this article is horrible[2]. It's poorly formatted and many parts sound very informal. I'm gonna mark it for cleanup. 69.161.13.68 22:36, 13 March 2006 (UTC)[reply]

That massive chunk[3] added by Mcgowan30 is just... a mess, and seems to be entirely focused on laser-based speed traps, but as an anon I'm hesitant to simply wipe it. — Preceding unsigned comment added by 142.167.179.232 (talk) 10:35, 20 March 2006 (UTC)[reply]
I just took my eye off this article for a few weeks and look what has happened. I agree entirely with the comment just above. It will need some work to tidy up, and it was never very good to start with. I would be prepared to have a go in producing a balanced shorter article. The first thing I would do is to move all the addition on the laser speed measurer to another article (presumably new - I'll have to check there is not already one covering this). Then I would write a paragraph to summarise what has been removed. Unless anybody argues against this I shall try and spend some time at the weekend on this. That is of course if no one else has had a go at a cleanup in the mean time. Op. Deo 22:39,a 22 March 2006 (UTC)
Back again! having nosed around a little it seems that the part added by Mcgowan30 is straight off a motorbiker's description of laser speed guns. It is therefore a copy violation unless the webpage author has released it for use in WP. I will therefore delete[4] the whole of it for now. I will come back at the weekend and try and write a short paragraph using the deleted material. The reference given below also contains useful background on the development of lidar as sensor for autonomous control of vehicles - a somewhat different type of instrumentation. Op. Deo 23:00, 22 March 2006 (UTC)[reply]

A resource[edit]

The following article (abstract) by the National Institute of Standards and Technology would provide some good background information to help with a cleanup of this section.

Performance Analysis of Next-Generation LADAR ... NISTIR 7117; 198 p. May 2004 (9 MB)

—Preceding unsigned comment added by Flyingpolarbear (talk • contribs) 19:33, 17 March 2006 (UTC)[reply]

Laser sources[edit]

600-800 nm lasers are most common for non-scientific applications. They are inexpensive and can be found with sufficient power but they are not eye-safe. Eye-safety is often a requirement for military applications. 1550 nm lasers are eye-safe but not common and are difficult to get with good power output. Laser settings include the laser repetition rate (which controls the data collection speed) and pulse length (which sets the range resolution).

LIDAR#Design

1550s aren't all that rare nowadays. I'm not really sure I buy the rep rate comment either. Maybe that's true for power, but if you needed a lot of power you'd be using a YAG anyway - right? - not a 600-800 diode. 600-800 isn't a very good range limit spec either if this is supposed to imply "conventional III-V edge-emitting diode" - 904 nm LIDARs are common as dirt. Is this section from an outdated source perhaps? Tarchon (talk) 21:25, 10 April 2006 (UTC)[reply]

A more general introduction, and more[edit]

All kinds of systems and applications use the term LIDAR. Not all LIDARs are based on lasers or pulses. And the distance measurement is only one of the measured parameters. I suggest the following more general introduction.

LIDAR (LIght Detection and Ranging or Laser Imaging Detection and Ranging) is a technology for remote sensing. In many ways it is similar to radar, but based on light instead of radio waves.

LIDAR technology has applications in several fields. Among other it is used for traffic surveillance, air pollution studies, remote spectroscopy and for precise mapping and distance measurements.

Other common terminology for LIDAR is LADAR or laser radar.

I am also working on a short general principle section. Which could be followed by the following applications section suggestion:

The primary difference between LIDAR and radar is that LIDAR uses much shorter wavelengths of the electromagnetic spectrum, typically in the ultraviolet, visible, or near infrared.

As the intensity of electromagnetic scattering from a particle depends on the wavelength light is sensitive to small particles like aerosols. LIDAR is therefore used to remotely measure airborne pollution, cloud formation and even clear atmosphere wind. LIDAR systems taking advantage of this phenomenon are DIAL and DWL.

An object needs to produce a dielectric discontinuity in order to reflect the transmitted wave. At radar (microwave or radio) frequencies a metallic object produces a significant reflection. However non-metallic objects, such as rain and rocks produce weaker reflections and some materials may produce no detectable reflection at all, meaning some objects or features are effectively invisible at radar frequencies.

A light-photon also has a more energetic energy quantum then a radio-wave photon and will interact with electrons and vibrational states of atoms and molecules. LIDAR is therefore used for remote spectroscopy of trace gases in the atmosphere, for example ozone, methane etc. For the same reasons it is used for measurements of chlorophyll for biomass studies. RAMAN LIDAR and DIAL.

The shorter wavelength also implies that very narrow beams can be produced, typically with a divergence of less than a milliradian. This characteristic allows distance and feature mapping with very high resolution compared with radar and that target clutter can be avoided. LIDAR are therefore used for missile guidance and traffic surveillance.

and finally a more detailed principle description of the different subsections.
— Preceding unsigned comment added by 130.225.79.64 (talk) 14:18, 12 April 2006 (UTC)[reply]

I agree about generalizing it. Restricting LIDAR to pulsed laser techniques is just incorrect. It might be better to describe that as the way LIDAR is usually done. I'm never quite sure where LIDAR ends and profiling begins though. I'd mention the disadvantages compared to RADAR too, not just the advantages. Short wavelengths also imply more scattering, less range, for example. Tarchon (talk) 00:50, 18 April 2006 (UTC)[reply]

LIDAR and RADAR interfering with one another[edit]

Does anybody know if lidar and radar were fixed on the same target from roughly the same place if they could mess with each other? — Preceding unsigned comment added by 69.156.43.137 (talk) 04:53, 2 June 2006

I can assure you that lidar (visible or near infrared light) and radar (microvawe range) use wavelengths differing by several orders of magnitude. Therefore no interference is possible. If it were, you would actually see microwave radiation interfering with light inside a microwave oven. It does not happen and intensity of both form of electromagnetic radiation in an oven are much higher than what a radar or lidar use to illuminate a target. Friendly Neighbour 05:49, 2 June 2006 (UTC)[reply]

The picture of the laser[edit]

I'm somewhat sceptical of the picture of the laser...if the laser interacted with air particles, it would encounter too much interference and would never reach the intended target, so I believe someone has skilfully photoshopped the picture with a lightsabre-like beam – anyone? — Preceding unsigned comment added by 195.172.14.80 (talk) 09:14, 26 June 2006 (UTC)[reply]

The bright laser beam is clearly impossible. First of all, it would break US safety rules on how intense beam you can send into the atmosphere (not to blind airplane pilots). It's either a fake (photoshop job) or a dual exposition photo (short daylight exposition overlayed on a long nighttime photo of the beam).
(continued) Yes, it's a dual exposition photo. You can see how the stars moved during the nighttime exposition in the original large photo while the clouds in the lower left corner (photographed in daylight) do not move (are not blurred). Friendly Neighbour 10:16, 26 June 2006 (UTC)[reply]
You are mistaken in general, and although I have no way of knowing if the particular image on the page is authentic or not, I have no reason to believe it is fake. Atmospheric research lidars in visible wavelengths are easily visible by the naked eye during nighttime, and have an appearance exactly like in this photo, except that the ones I've seen myself have all been green. To ensure aviation safety, powerful lidars are marked on aviators' maps, and there are exclusion zones around them. Operators also use protective goggles which block the wavelength of the lidar.
As for your claim that this is a dual exposure, I suggest you take a look at many more nighttime long-exposure photos before you make strong claims of forgery. In what way do you suggest that it was necessary to make a daytime exposure to create this scene? --Togr 07:37, 22 July 2007 (UTC)[reply]

Removed {{cleanup}} tag[edit]

The article[5] seems well organized and well written, although a bit technically confusing with all the terms you use. You need to add a reference section for citations sourcing your information. KarenAnn (talk • contribs) 15:21, 6 July 2006 (UTC)[reply]

Lidar measurements and techniques[edit]

I think there should be a section listing the different techniques for measuring each parameter such as aerosol type and air temperature. —Preceding unsigned comment added by Cap.fwiffo (talk • contribs) 21:18, 20 August 2006 (UTC)[reply]

You are free to start one. However the techniques for different aerosol types are identical; the only thing that differs them is the backscattering coefficient for a given particle size / wavelength combination. It's the trace gases that need a different approach. Friendly Neighbour 21:24, 20 August 2006 (UTC)[reply]
I'm afraid Friendly Neighbour misspoke. Even for aerosols, there are a number of different measurement techniques that are commonly used. Simple backscatter lidar (e.g., the spaceborne lidars GLAS and CALIPSO), Raman lidar, and high spectral resolution lidar (HSRL) are all commonly used to measure both cloud and aerosol properties. For trace gases, differential absorption lidar (DIAL) is the tool of choice...but even DIAL can be (and is) used to make aerosol measurements. Xavier onnasis (talk • contribs) 18:55, 29 December 2006 (UTC)[reply]

In fiction section?[edit]

LIDAR may be used in science fiction as an alternative to RADAR. I'd add a section but I'm not sure it meets notability requirements, as the only thing I know of for sure that uses it is Space: Above and Beyond. 69.81.123.154 (talk) 18:26, 24 December 2006 (UTC)[reply]

Restored link to KQED[edit]

Hey y'all: I've reverted[6] a previous removal of a KQED-TV (PBS) science story from LIDAR#External links. I didn't get a reply from User:JuJube after requesting clarification for removal. Craigrosa (talk) 18:13, 16 May 2007 (UTC)[reply]

WP:EL: No link should be added unless its inclusion is justified. Until there is consensus for its inclusion the link should not be reincluded. Femto 12:24, 2 June 2007 (UTC)[reply]

Links to vendors[edit]

How about a link or mention somewhere of some of the leading commercial contenders eg:

[ Since editors started to add suggestions here to the 2 by Davagh, I moved the whole list down to below Davagh's signature. --83.253.244.23 (talk) 18:30, 5 December 2010 (UTC) ][reply]

I see there is already a link[7] from the Zephir disambiguation page to this lidar article. Other sources of information on these products at:

Davagh (talk) 16:00, 27 February 2009 (UTC)[reply]

Please put your additional suggestion at the end of this list, and sign it with four tildes (~~~~).

This page slows down my browser[edit]

This is the only Wikipedia page that has ever slowed down my browser. Is it because of the animated pictures? Running Mac OS X and Firefox. — Preceding unsigned comment added by 76.17.212.193 (talk) 00:51, 21 September 2009 (UTC)[reply]

More on the definition of light[edit]

(Comment moved down from Aren't radio waves light, technically? above, due to the age of that discussion. --83.253.248.109 (talk) 13:49, 20 April 2010 (UTC))[reply]

The article on light is ambiguous on this discussion ("In physics, the term light sometimes refers to electromagnetic radiation of any wavelength, whether visible or not"[8]). It would seem most clear to simply edit the lede to remove "which is light that is not in the visible spectrum..." (the clause[9] is unnecessary and reads somewhat awkwardly anyway, I think). A reasonable alternative would be "which is electromagnetic radiation not in the visible spectrum," I think. Not that this is a huge issue, but the wording is odd enough to have caused me to click the discussion tab. ;) 131.107.0.102 (Microsoft web proxy) 19:03, 10 November 2009 (UTC)[reply]

Is the term "laser radar" really misleading?[edit]

The sentence about calling "laser radar...misleading"[10] doesn't feel right. My logic is that LIDAR would in fact be a type of radar. Many of what we call radars utilize the microwave bit of the spectrum. Radar grew beyond its original acronym some time ago. Do even shorter wavelengths make a radar not? ~ Theparadigmshifter (talk) 06:45, 23 January 2010 (UTC)[reply]

"Laser radar" simply means: "like radar, but with laser light" (instead of radio waves).
I see the two most basic properties of a radar system as: 1) The basic working principle, which on a very general level is sending something out and detecting its reflection, and 2) The sending and detection of radio waves or microwaves. The first is shared by LIDAR, and the second just differs in which part of the electromagnetic spectrum that is used.
The only way I can see that one could be mislead by the term "laser radar", is if one thinks that the word radar in the phrase means that "laser radar" involves radio waves or microwaves. But one who knows that much about radar, most likely is able to figure out that the word laser in the term means that that part of the electromagnetic spectrum is used, rather than radio or micro waves as in radar.
(Also, to claim that something is misleading, you should either be able to show that someone has been mislead by it in any significant way, or, at the very least, show in some way that people are likely to be mislead by it.
And just in case you find someone who has managed to become mislead in some way by this term; is that of enough statistical significance or notable enough to deem the term "misleading" in the lead section (or anywhere else)?)
In my opinion, the term "laser radar" is not misleading in any significant way. --83.253.248.109 (talk) 23:24, 21 April 2010 (UTC)[reply]
Bye the way, ever heard about "optical maser"? That's a "maser", which instead of emitting microwaves like a regular maser, emits radiation in or near the visible spectrum. It's also called a "laser". --83.253.248.109 (talk) 23:53, 21 April 2010 (UTC)[reply]
Replaced[11] "but is misleading because"  with "even though", to avoid the word misleading. --83.253.251.169 (talk) 09:36, 27 April 2010 (UTC)[reply]

Yeah, if you can show me a "light radio" then MAYBE you could say "laser radar" is not misleading. Ultimately, this term is inaccurate, un-scientific and misleading. See the similar discussion above[12] or just learn the EM spectrum. 132.38.190.22 (talk) 14:25, 13 July 2010 (UTC)[reply]

Perhaps mention survey of Caracol under the Archaeology heading?[edit]

A couple of days ago (mid May 2010), several publications were made about how NASA has used LIDAR to survey Caracol, a large Maya city. Could be interesting to mention this and provide suitable links to more information. TobiF (talk) 11:33, 18 May 2010 (UTC)[reply]

File:Paraplane in air.png nominated for speedy deletion[edit]

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Robotics attention needed[edit]

  • Refs - large swathes of text need refs
  • Content - complete?
  • Reassess
  • Check (from feedback footpage): "147.102.195.66 posted feedback to LIDAR3 months ago - The citation missing in "Meteorology and Atmospheric environment" could be: Weitkamp, C. (Ed.), Lidar: Range-Resolved Optical Remote Sensing of the Atmosphere, Series: Springer Series in Optical Sciences, Vol. 102. 2005."

Chaosdruid (talk) 11:12, 24 March 2012 (UTC)[reply]

LIDAR in the film industry[edit]

I noted a credit for "on set Lidar scanner" in the recent movie Total Recall. I gather moviemakers are now using LIDAR to scan objects that are going to be represented in CGI? There should be a section on this in the article. 38.111.35.2 (talk) 16:20, 14 August 2012 (UTC)[reply]

I worked in the business until recently. Over the past few months my friends have seen Lidar used in location and sets scanning for the art department or for animation/cgi. CGI set extensions have been going on for a while, so it's been useful in helping to cut down labour in that regard. Set it up and get a lovely 3d model in an afternoon? Absolutely someone should write something about this. — Preceding unsigned comment added by 70.53.64.27 (talk) 22:53, 13 May 2014 (UTC)[reply]

Propose renaming article to Lidar instead of LIDAR[edit]

Most publications use "lidar" not "LIDAR". To be honest, this is a more logical spelling, since lidar is not an acronym, see the revisions at LIDAR#Derivation and spelling of LIDAR, which provides a history of the usage. I think we should acknowledge this, and rename the article Lidar. Thoughts? Edgar Vekilnik, Jr. (talk) 02:49, 4 May 2013 (UTC)[reply]

Okay, seeing no objections, I'll make the change. Edgar Vekilnik, Jr. (talk) 12:33, 8 May 2013 (UTC)[reply]

Requested move[edit]

The following discussion is an archived discussion of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

The result of the proposal was moved. --BDD (talk) 18:12, 15 May 2013 (UTC)[reply]

LIDAR → Lidar – 1. Lidar is not an acronym, it is a portmanteau of "light" and "radar", as it is stated in the first published reference (James Ring, "The Laser in Astronomy." p. 672-3, New Scientist Jun 20, 1963). 2. Even if you believe it is an acronym, it should not be all caps, since it follows the pattern of "laser" and "radar". 3. Most publications use "lidar", not "LIDAR" (see Google Books: [[13]]}. Edgar Vekilnik, Jr. (talk) 13:02, 8 May 2013 (UTC)[reply]

Even if it was, radar is in lower case, not all caps. I have no problems with the move. Thegreatdr (talk) 14:57, 8 May 2013 (UTC)[reply]
  • Support per laser, radar, sonar, etc. Powers T 15:25, 8 May 2013 (UTC)[reply]
  • Comment it is an acronym. "LIght Detection And Ranging" is a frequently found expansion. Further, in many documents in the past, LASER and RADAR were capitalized (though not in the modern day, as they've transitioned from being pure acronyms into common words) -- 65.94.76.126 (talk) 04:48, 9 May 2013 (UTC)[reply]
  • support this acronym has evolved into being a word. -- 65.94.76.126 (talk) 04:56, 9 May 2013 (UTC)[reply]
The above discussion is preserved as an archive of the proposal. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

BDD (talk) 18:12, 15 May 2013‎ (UTC)[reply]

LADAR Lives.[edit]

When this article was moved from LADAR to LIDAR to Lidar all mention of LADAR was deleted. However, at least the USAF continues to use the term LADAR. The redirect left behind does not explain that LADAR is still in use, even if it is not the more common name. I believe the etymology section needs to add a mention of this alternative name. --Lineagegeek (talk) 21:35, 17 August 2013 (UTC)[reply]

Sounds good. I have no objection to your inclusion of a Ladar section. I think you should do it lowercase, since its cognates, laser, lidar, radar, and sonar, have long been lowercase. Edgar Vekilnik, Jr. (talk) 20:39, 18 August 2013 (UTC)[reply]

External links modified[edit]

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Did Lidar invent LIDAR?[edit]

Is there a good source that debunks this? It doesn't seem to want to die otherwise. Andy Dingley (talk) 10:55, 4 October 2015 (UTC)[reply]

Lidar in Forestry section[edit]

I would like to add a section on lidar use in forestry. Any thoughts?

Here is a source I would use for reference:

[1]

Loganbarrett28 (talk) 04:36, 14 March 2017 (UTC)Logan Barrett[reply]

References

  1. ^ http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.675.3092&rep=rep1&type=pdf

Lidar spelling in article[edit]

Putting this on the talk page for future editors. I just went through and changed all (hopefully) the different spellings of lidar, for consistency. I used the NY Times format of lidar, non-capitalized in any way, unless it's the start of a sentence. If other groups use LiDAR or LIDAR I left those references alone. Timtempleton (talk) 23:00, 13 April 2017 (UTC)[reply]

Purge autonomous vehicle methods[edit]

The 3 example papers for "Approaches of processing lidar data" are absolute rubbish. These are papers in third tier conferences and workshops that have absolutely no impact (23/4/10 citations). The summaries have very low quality and plenty of obvious mistakes. As an example "using Fast R-CNN[53] as this method doesn't need training" is completely false! I suggest to remove all of them or have at most one sentence per method. — Preceding unsigned comment added by 31.10.144.135 (talk) 12:41, 17 November 2017 (UTC)[reply]

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External links modified (January 2018)[edit]

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Images[edit]

The images at the top of the article are really messy and it makes you scroll a good amount before getting to the article. Should I add a gallery section? Lord David, Duke of Glencoe (talk) 21:08, 6 February 2018 (UTC)[reply]

It may be the application you're using to view the page. I don't see that problem on my desktop computer. The only thing that stands out is the exceptional width of the table of contents. Try viewing the page on other devices. Eric talk 00:53, 7 February 2018 (UTC)[reply]

Uber self-driving car?[edit]

The picture of the "Uber self-driving car" has someone at the wheel. Are we sure this is a self-driving car? Morfusmax (talk) 16:22, 9 February 2018 (UTC)[reply]

The photo in the article as of 2021/03/02 is not an Uber robot car. The actual, infamous Uber robot car had a safety driver, but she was not paying attention.[1] Also, the Lidar was not connected to the brakes. [2][3] JHowardGibson (talk) 18:39, 2 March 2021 (UTC)[reply]

References

  1. ^ BBC: Uber's self-driving operator charged over fatal crash
  2. ^ CBC: Self-driving Uber was aware of pedestrian but didn't stop, probe on fatal Arizona crash finds
  3. ^ NTSB: Preliminary Report Highway HWY18MH010

First sentence inaccuracies[edit]

The first sentence says that lidar is "a surveying method that measures distance to a target by illuminating the target with pulsed laser light and measuring the reflected pulses with a sensor". This scope is too narrow on at least three accounts:

  • First, not all lidars are used to measure distance. Lidar can be used to measure surface reflectivity, atmospheric conditions, and speed. Doppler lidar, for example, measures wind speed by measuring the frequency shift of light that has been backscattered by the air. Differential absorption lidar detects trace amounts of gases by measuring the difference in attenuation of two wavelengths of light, only one of which is absorbed by the target gas. Neither of these examples measures range.
  • Second, not all ranging lidars use pulsed light. There are continuous wave lidars, which can be either amplitude- or frequency-modulated at, say, gigahertz frequencies. These can measure range without using pulsed light; instead, they interfere the continuous outgoing signal with the return signal and analyze the beat (wave physics).
  • Third, not all lidars are used for surveying. As the article proceeds to mention, it is used in many industries for many applications.

I suggest replacing the first sentence with something like, "Lidar is a type of sensor which obtains information by bouncing light off a target. Such information may include distance to target, direction of the target, reflectance, speed, or atmospheric conditions."

I also think that the article itself needs a huge amount of cleanup. I can probably look into reorganizing a lot of it when I have the time, although I'm working for a lidar manufacturer so it is probably best that someone else does it. For a good technical overview, I recommend the SPIE Field Guide to Lidar. dllu (t,c) 10:18, 9 June 2018 (UTC)[reply]

More detailed "history" section[edit]

I'd enjoy if the history section included a timeline of when each application went into common service, or at least if the application sections included those years. If others agree this is a good idea, I can go ahead with a rough pass, with citations of course. Adamw (talk) 07:08, 1 October 2018 (UTC)[reply]

History and etymology - Radar/Raider claim[edit]

No reference given for the claim that Radar is a pronunciation error of raider. Sounds very suspicions. Given the article isn't even about Radar, might be best to remove? — Preceding unsigned comment added by ChrisH256 (talk • contribs) 19:54, 23 April 2019 (UTC)[reply]

Lidar safety concerns[edit]

I wonder if others might have more information to create a section about Lidar safety conserns. BBC made an article a while back about a photo-camera being ruined by a car with lidar (https://www.bbc.com/news/technology-46875947), so I wonder if there isn't more. 62.238.252.34 (talk) 09:37, 20 October 2020 (UTC)[reply]

The safety problem with Lidar is the laser. Wikipedia has an article on Laser safety which covers most of the problem. The only issue I can think of as unique to Lidar is that eye‑safe Class 1 lasers are strongly preferred. On airborne Lidars, the system may be Class 4 at the bottom of the aircraft, and Class 1 at some minimum altitude above the ground. The aircraft does not activate the Lidar below that altitude, which is not much of a problem because aircraft don't like flying at those low altitudes anyway. Design practise on Lidars is to use a beam expander to accomplish Class 1 level energy densities.[1] I know this because I used to work in the industry. I am searching Google for this stuff, and not finding much. JHowardGibson (talk) 19:34, 23 February 2021 (UTC)[reply]

References

  1. ^ https://www.photonics.com/Articles/Not_All_Beams_Are_Created_Equal/a56477

iPhone iPad Lidar[edit]

I’d like more info on how iPhone 12 Pro Max does Lidar. DBGustavson (talk) 20:27, 10 July 2021 (UTC)[reply]

Featured picture scheduled for POTD[edit]

Hello! This is to let editors know that File:Ouster OS1-64 lidar point cloud of intersection of Folsom and Dore St, San Francisco.png, a featured picture used in this article, has been selected as the English Wikipedia's picture of the day (POTD) for January 27, 2022. A preview of the POTD is displayed below and can be edited at Template:POTD/2022-01-27. For the greater benefit of readers, any potential improvements or maintenance that could benefit the quality of this article should be done before its scheduled appearance on the Main Page. If you have any concerns, please place a message at Wikipedia talk:Picture of the day. Thank you! Cwmhiraeth (talk) 11:25, 22 January 2022 (UTC)[reply]

Lidar

Lidar is a method for determining ranges by targeting an object with a laser and measuring the time taken by the reflected light to return to the receiver. Lidar can also be used to make digital 3-D representations of areas on the Earth's surface and ocean floor, due to differences in laser return times, and by varying laser wavelengths. It has terrestrial, airborne, and mobile applications. This image shows an orthographic projection of a registered point cloud depicting the intersection of Folsom Street and Dore Street in San Francisco, California. The point cloud was captured over 18 seconds and registered in real time using an Ouster OS1 lidar unit mounted on a moving car. The points are coloured by a function based on raw lidar intensity multiplied by range, with orange signifying brighter regions and dark blue for darker regions. Lidar is a popular sensor for self-driving cars.

Image credit: Daniel L. Lu

Wind measurement[edit]

See https://www.sunwindenergy.com/news/lidar-controls-wind-turbine#:~:text=The%20LIDAR%20(light%20detection%20and,before%20it%20reaches%20the%20turbine.

LIDAR in this sense is a related means of measuring wind speed at a distance, using much the same technology. Andrewa (talk) 17:12, 1 June 2022 (UTC)[reply]

Requirement of Gallium-Arsenide imagers Still True for Flash LiDAR?[edit]

There is an older source from 2018 saying that flash LiDAR cannot be done using silicon photonics in an eye-safe range and requires Gallium-Arsenide photonics. Is this still true? It seems like SiLc’s product might make this assumption false by proof by contradiction. I also thought using OPA made silicon photonics viable for flash LiDAR.

I am not an expert, but would appreciate any experts chipping in to re-examine this source for accuracy. 2603:8080:6001:9C81:0:0:0:1008 (talk) 14:46, 18 February 2023 (UTC)[reply]

Use of LIDAR in Additive Manufacturing[edit]

LIDAR was recently incorporated with 3D Printing in Bambu Lab's X1 Carbon. Would this be a worthwhile addition to the article? Trojari (talk) 15:19, 20 March 2023 (UTC)[reply]

If there are independent reliable sources, perhaps. MrOllie (talk) 15:26, 20 March 2023 (UTC)[reply]

Error in "Technology/Mathematical formula" section[edit]

"Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "http://localhost:6011/en.wikipedia.org/v1/":): {\displaystyle d=\frac{c\cdot t}{2}}" Zhamelax (talk) 08:49, 27 September 2023 (UTC)[reply]

EH Synge[edit]

How do i add a reference to a Wikipedia article on Edward Hutchinson Synge, who did theoretical work on LIDAR in 1930? Wikiijohn (talk) 03:38, 25 January 2024 (UTC)[reply]

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