Traffic-sign recognition

<h2 id="history">History</h2>

The <a href="/facts/Vienna_Convention_on_Road_Signs_and_Signals/VLh7vjAl">Vienna Convention on Road Signs and Signals</a> is a treaty signed in 1968 which has been able to standardize traffic signs across different countries. About 52 countries have signed this treaty, which includes 31 countries from Europe. The convention has broadly classified the road signs into seven categories designated with letters A to H. This standardization has been the main drive for helping the development of traffic-sign recognition systems that can be used globally.

Traffic-sign recognition first appeared, in the form of speed limit sign recognition, in 2008 for the 2009 <a href="/facts/Vauxhall_Insignia/2rjxWoPf">Vauxhall Insignia</a>.<a class="footnote-ref" id="fnref:1" href="#fn:1">1</a> Later in 2009 they appeared on the new <a href="/facts/BMW_F01/XICAff1l">BMW 7 Series</a>, and the following year on the <a href="/facts/Mercedes-Benz_S-Class/Fh8u0umh">Mercedes-Benz S-Class</a>. At that time, these systems only detected the round speed limit signs found all across Europe (e.g.<a class="footnote-ref" id="fnref:2" href="#fn:2">2</a>).
Second-generation systems can also detect overtaking restrictions. It was introduced in 2008 in the <a href="/facts/Opel_Insignia/2rjxWoPf">Opel Insignia</a>,<a class="footnote-ref" id="fnref:3" href="#fn:3">3</a> later followed by the <a href="/facts/Opel_Astra/UFPqMrIV">Opel Astra</a> and the <a href="/facts/Saab_9-5/mPggv7ba">Saab 9-5</a>. This technology is also available on the 2011 <a href="/facts/Volkswagen_Phaeton/JMVzqCeh">Volkswagen Phaeton</a><a class="footnote-ref" id="fnref:4" href="#fn:4">4</a> and, since 2012, in the <a href="/facts/Volvo_S80/z0No5Tru">Volvo S80</a>, <a href="/facts/Volvo_V70/Y3ykgc0t">V70</a>, XC70, <a href="/facts/Volvo_XC60/Ek8wv5s5">XC60</a>, <a href="/facts/Volvo_S60/0RWL5jvQ">S60</a>, <a href="/facts/Volvo_V60/FRa2ocJa">V60</a> and <a href="/facts/Volvo_V40_(2012%25E2%2580%25932019)/FjbUox2h">V40</a>, as a technology called Road Sign Information.<a class="footnote-ref" id="fnref:5" href="#fn:5">5</a> They are not able to recognize city limit signs, which in most European countries are associated with speed limits, as they are too similar to direction signs.
Such systems are expected to be mandatory on new cars sold in the EU from May 2022<a class="footnote-ref" id="fnref:6" href="#fn:6">6</a><a class="footnote-ref" id="fnref:7" href="#fn:7">7</a> which should apply regulation 2021/1958 from 23 June 2021.<a class="footnote-ref" id="fnref:8" href="#fn:8">8</a>

<h2 id="implementation">Implementation</h2>

Traffic signs can be analyzed using forward-facing cameras in many modern cars, vehicles and trucks. One of the basic use cases of a traffic-sign recognition system is for speed limits. Most of the <a href="/facts/Global_Positioning_System/DKVLnzF3">GPS</a> data would procure speed information, but additional speed limit traffic signs can also be used to extract information and display it in the dashboard of the car to alert the driver about the road sign. This is an advanced <a href="/facts/Advanced_driver-assistance_system/8l0vVnKd">driver-assistance</a> feature available in most high-end cars, mainly in European vehicles.

Modern traffic-sign recognition systems are being developed using convolutional neural networks, mainly driven by the requirements of autonomous vehicles and <a href="/facts/Self-driving_car/KXeFywXS">self-driving cars</a>. In these scenarios, the detection system needs to identify a variety of traffic signs and not just speed limits. This is where the <a href="/facts/Vienna_Convention_on_Road_Signs_and_Signals/VLh7vjAl">Vienna Convention on Road Signs and Signals</a> comes to help. A convolutional neural network can be trained to take in these predefined traffic signs and 'learn' using <a href="/facts/Deep_Learning/JLuwD3ea">Deep Learning</a> techniques.
The neural net in turn uses <a href="/facts/Image_Processing/zenalNCf">Image Processing</a> and <a href="/facts/Computer_Vision/Tl2Yyk66">Computer Vision</a> to train the network with its potential outcomes. The trained neural net can then be used in real time to detect new traffic signs in real time. Self driving car companies including <a href="/facts/Waymo/7BVtuwXz">Waymo</a> and <a href="/facts/Uber/rHcJcp6S">Uber</a> are generating and outsourcing traffic-sign data sets along with map and navigation companies like <a href="/facts/TomTom/KBAVAsxg">Tom Tom</a>.<a class="footnote-ref" id="fnref:9" href="#fn:9">9</a> Advanced <a href="/facts/Computer_vision/Tl2Yyk66">computer vision</a> and neural network techniques make this goal highly efficient and achievable in real time.

There are diverse algorithms for traffic-sign recognition. Common ones are those based on the shape of the sign board. Typical sign board shapes like hexagons, circles, and rectangles define different types of signs, which can be used for classification. Other major algorithms for character recognition includes <a href="/facts/Haar-like_feature/copGPcca">Haar-like features</a>, Freeman <a href="/facts/Chain_code/MSEMcR3j">Chain code</a>, AdaBoost detection and <a href="/facts/Deep_learning/JLuwD3ea">deep learning</a> <a href="/facts/Neural_networks/DDhJTfMc">neural networks</a> methods. Haar-like features can be used to create cascaded classifiers which can then help detect the sign board characters.
Deep learning can be incorporated into traffic-sign detection. Polygonal approximation of digital curves using <a href="/facts/Ramer%25E2%2580%2593Douglas%25E2%2580%2593Peucker_algorithm/VT31304N">Ramer–Douglas–Peucker algorithm</a> can be used to detect the shape of the sign boards and methods like <a href="/facts/Support_Vector_Machines/XobxpdBG">Support Vector Machines</a> and Byte-MCT with an <a href="/facts/AdaBoost/nwJ6znVj">AdaBoost</a> classifier has been used in one of the methods to detect traffic signs.<a class="footnote-ref" id="fnref:10" href="#fn:10">10</a>
Identification of speed limit signs also needs to take into account the units used in a particular area. For instance, a vehicle travelling from <a href="/facts/Northern_Ireland/Jmr0NRyl">Northern Ireland</a> to <a href="/facts/Republic_of_Ireland/k8JzXVze">Ireland</a> would need to be able to differentiate the km/h speed limit signage in Ireland from the mph speed limit signage still used in Northern Ireland, which is particularly important when traffic sign recognition is linked to <a href="/facts/Intelligent_speed_assistance/FGDa2qWU">Intelligent speed assistance</a> systems. <a href="/facts/Geofence/p9R1RuSJ">Geofencing</a> and reference to online navigation <a href="/facts/Database/VYcpkevb">databases</a> can be used as a hint to the <a href="/facts/Algorithm/fnl5NmRt">algorithm</a> to identify which units are likely to be in use.<a class="footnote-ref" id="fnref:11" href="#fn:11">11</a>

<h2 id="usage">Usage</h2>
Information gathered from road signs by a forward facing camera is used in Tesla's <a href="/facts/Tesla_Autopilot/1lS4a4Bf">Autosteer</a> and <a href="/facts/Tesla_Autopilot/1lS4a4Bf">Traffic-aware Cruise Control</a> Systems to bring the vehicle to a stop if a stop sign is detected.<a class="footnote-ref" id="fnref:12" href="#fn:12">12</a> After a recent software update many Tesla vehicles upload the speed limit data collected by their cameras to Tesla's navigation software for all other vehicles to use.

<h2 id="car-makers-and-vehicles">Car makers and vehicles</h2>
Some cars with such system are made by <a href="/facts/Audi/AEyDIbTo">Audi</a>,
<a href="/facts/BMW/cJd8y02r">BMW</a>,
<a href="/facts/Citro%25C3%25ABn/cF96vY9S">Citroën</a>,
<a href="/facts/Ford_Motor_Company/lY6Wcwty">Ford</a>,
<a href="/facts/Honda/asGvEBbW">Honda</a>,
<a href="/facts/Infiniti/9Evzuy22">Infiniti</a>,
<a href="/facts/Jaguar/7I665Dny">Jaguar</a>,
<a href="/facts/Jeep/6f5snxWn">Jeep</a>,
<a href="/facts/Land_Rover/oNTGb5XQ">Land Rover</a>,
<a href="/facts/Lexus/j6nKkWN8">Lexus</a>,
<a href="/facts/Mercedes-Benz/pGrJrQHC">Mercedes</a>,
<a href="/facts/Nissan/1m2uVLE4">Nissan</a>,
<a href="/facts/Opel/hFsySxoa">Opel</a>,
<a href="/facts/Peugeot/Y7M6sq1D">Peugeot</a>,
<a href="/facts/Porsche/9S83Lb11">Porsche</a>,
<a href="/facts/Renault/obzoLxSN">Renault</a>,
<a href="/facts/Toyota/wHIb40oG">Toyota</a>,
<a href="/facts/Volkswagen/LDkDEfDu">Volkswagen</a>, <a href="/facts/Tesla%2c_Inc./dSyLNM1D">Tesla</a> and
<a href="/facts/Volvo/JUFSUUYD">Volvo</a>.
For instance:

<ul><li>Audi: <a href="/facts/Audi_A8/NlUoYMKo">Audi A8</a></li>
<li>BMW: <a href="/facts/BMW_7_Series/UXdD6WvF">BMW 7 Series</a>, <a href="/facts/BMW_5_Series_Gran_Turismo/xkwq2MFb">BMW 5 Series Gran Turismo</a>, <a href="/facts/BMW_5_Series/6WtteFQb">BMW 5 Series</a></li>
<li>Mercedes: <a href="/facts/Mercedes-Benz_E_Class/r5BscDGY">Mercedes-Benz E Class</a>, <a href="/facts/Mercedes-Benz_S_Class/Fh8u0umh">Mercedes-Benz S Class</a></li>
<li>Opel: <a href="/facts/Opel_Insignia/2rjxWoPf">Opel Insignia</a>, <a href="/facts/Opel_Corsa/DE2H5bLb">Opel Corsa</a></li>
<li><a href="/facts/Saab_9-5/mPggv7ba">Saab 9-5</a></li>
<li><a href="/facts/Volkswagen_Phaeton/JMVzqCeh">Volkswagen Phaeton</a></li>
<li>Lexus: <a href="/facts/Lexus_GS/mr9DsF56">Lexus GS</a>, <a href="/facts/Lexus_LS/Txn2UwKD">Lexus LS</a>, <a href="/facts/Lexus_RX/Jgj1IQqN">Lexus RX</a> 2022+</li>
<li><a href="/facts/Tesla%2c_Inc./dSyLNM1D">Tesla</a>: <a href="/facts/Tesla_Model_X/1vW31zVf">Model X</a>, <a href="/facts/Tesla_Model_S/2gSqw8RU">Model S</a>, <a href="/facts/Tesla_Model_Y/SLBfQsTz">Model Y</a>, <a href="/facts/Tesla_Model_3/cLFeRCvX">Model 3</a></li></ul>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Intelligent_speed_adaptation/FGDa2qWU">Intelligent speed adaptation</a></li>
<li><a href="/facts/Intelligent_car/hhmnmpcu">Intelligent car</a></li>
<li><a href="/facts/Vehicular_automation/hhmnmpcu">Self Driving Vehicles</a></li>
<li><a href="/facts/Tesla_Autopilot/1lS4a4Bf">Tesla Autopilot</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1">"Vauxhall Insignia to read speed limit signs". Business Car. 18 June 2008. Retrieved 2 April 2019. <a href="https://www.businesscar.co.uk/news/2008/vauxhall-insignia-to-read-speed-limit-signs" target="_blank">https://www.businesscar.co.uk/news/2008/vauxhall-insignia-to-read-speed-limit-signs</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></li>
<li id="fn:2">Eichner, M.; Breckon, T. (2008). "Integrated speed limit detection and recognition from real-time video" (PDF). 2008 IEEE Intelligent Vehicles Symposium. pp. 626–631. doi:10.1109/IVS.2008.4621285. ISBN 978-1-4244-2568-6. S2CID 12477544. <a href="978-1-4244-2568-6" target="_blank">978-1-4244-2568-6</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></li>
<li id="fn:3">"Assistenzsystem von Opel – Das magische Auge". 18 June 2008. Retrieved 17 December 2010. <a href="http://www.autobild.de/artikel/assistenzsystem-von-opel-722126.html" target="_blank">http://www.autobild.de/artikel/assistenzsystem-von-opel-722126.html</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></li>
<li id="fn:4">"Phaeton debuts with new design and new technologies". Archived from the original on 20 July 2011. Retrieved 22 April 2010. <a href="https://web.archive.org/web/20110720152841/https://www.volkswagen-media-services.com/medias_publish/ms/content/en/pressemitteilungen/2010/04/22/phaeton_debuts_with.standard.gid-oeffentlichkeit.html" target="_blank">https://web.archive.org/web/20110720152841/https://www.volkswagen-media-services.com/medias_publish/ms/content/en/pressemitteilungen/2010/04/22/phaeton_debuts_with.standard.gid-oeffentlichkeit.html</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></li>
<li id="fn:5">"Road Sign Information". Retrieved 19 February 2013. <a href="https://www.media.volvocars.com/global/enhanced/en-gb/Media/Preview.aspx?mediaid=47896" target="_blank">https://www.media.volvocars.com/global/enhanced/en-gb/Media/Preview.aspx?mediaid=47896</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></li>
<li id="fn:6">Procedure 2018/0145/COD <a href="https://eur-lex.europa.eu/legal-content/EN/HIS/?uri=CELEX:32019R2144" target="_blank">https://eur-lex.europa.eu/legal-content/EN/HIS/?uri=CELEX:32019R2144</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></li>
<li id="fn:7">"Briefing: Intelligent Speed Assistance (ISA) | ETSC". etsc.eu. 27 September 2017. Retrieved 30 August 2020. <a href="https://etsc.eu/briefing-intelligent-speed-assistance-isa/" target="_blank">https://etsc.eu/briefing-intelligent-speed-assistance-isa/</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></li>
<li id="fn:8">Commission Delegated Regulation (EU) 2021/1958 of 23 June 2021 supplementing Regulation (EU) 2019/2144 of the European Parliament and of the Council by laying down detailed rules concerning the specific test procedures and technical requirements for the type-approval of motor vehicles with regard to their intelligent speed assistance systems and for the type-approval of those systems as separate technical units and amending Annex II to that Regulation (consolidated text) <a href="https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:02021R1958-20230921" target="_blank">https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:02021R1958-20230921</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></li>
<li id="fn:9">"Whoever Owns the Maps Owns the Future of Self-Driving Cars". July 2016. <a href="http://www.popularmechanics.com/cars/a21609/here-maps-future-of-self-driving-cars/" target="_blank">http://www.popularmechanics.com/cars/a21609/here-maps-future-of-self-driving-cars/</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></li>
<li id="fn:10">Lim, K.; Hong, Y.; Choi, Y.; Byun, H. (2017). "Lim K, Hong Y, Choi Y, Byun H (2017) Real-time traffic-sign recognition based on a general-purpose GPU and deep learning. PLoS ONE 12(3): e0173317". PLOS ONE. 12 (3): e0173317. doi:10.1371/journal.pone.0173317. PMC 5338798. PMID 28264011. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5338798" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5338798</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></li>
<li id="fn:11">"ADAS Map Speed Limits Improve mandatory Intelligent Speed Assistance and vehicle safety ratings" (PDF). <a href="https://download.tomtom.com/open/banners/Whitepaper-ADAS-Map-Speed-Limits-Improve-mandatory-Intelligen-Speed-Assistance-and-vehicle-safety-ratings.pdf" target="_blank">https://download.tomtom.com/open/banners/Whitepaper-ADAS-Map-Speed-Limits-Improve-mandatory-Intelligen-Speed-Assistance-and-vehicle-safety-ratings.pdf</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></li>
<li id="fn:12">"Tesla Model 3 user's guide to autopilot". <a href="https://www.tesla.com/ownersmanual/model3/en_us/GUID-A701F7DC-875C-4491-BC84-605A77EA152C.html#:~:text=The%20cameras%20ca" target="_blank">https://www.tesla.com/ownersmanual/model3/en_us/GUID-A701F7DC-875C-4491-BC84-605A77EA152C.html#:~:text=The%20cameras%20ca</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></li>
</ol>

Traffic-sign recognition open-in-new

Traffic-sign recognition