<span class="mw-page-title-main">Boids</span>

Boids

<p><b>Boids</b> is an <a href="/en/Artificial_life" title="Artificial life" class="wl">artificial life</a> program, developed by <a href="/en/Craig_Reynolds_(computer_graphics)" title="Craig Reynolds (computer graphics)" class="wl">Craig Reynolds</a> in 1986, which simulates the <a href="/en/Flocking_(behavior)" title="Flocking (behavior)" class="wl">flocking</a> behaviour of <a href="/en/Bird" title="Bird" class="wl">birds</a>. His paper on this topic was published in 1987 in the proceedings of the <a href="/en/Association_for_Computing_Machinery" title="Association for Computing Machinery" class="wl">ACM</a> <a href="/en/SIGGRAPH" title="SIGGRAPH" class="wl">SIGGRAPH</a> conference.<span class="mw-ref reference" id="cite_ref-1"><a href="#cite_note-1" style="counter-reset: mw-Ref 1;"><span class="mw-reflink-text">[1]</span></a></span> The name "boid" corresponds to a shortened version of "bird-oid object", which refers to a bird-like object.<span class="mw-ref reference" id="cite_ref-2"><a href="#cite_note-2" style="counter-reset: mw-Ref 2;"><span class="mw-reflink-text">[2]</span></a></span> "Boid" is also a <a href="/en/New_York_accent" title="New York accent" class="wl">New York Metropolitan dialect pronunciation</a> for "bird."</p>

<style data-mw-deduplicate="TemplateStyles:r1096954695/mw-parser-output/.tmulti" typeof="mw:Extension/templatestyles mw:Transclusion">.mw-parser-output .tmulti .multiimageinner{display:flex;flex-direction:column}.mw-parser-output .tmulti .trow{display:flex;flex-direction:row;clear:left;flex-wrap:wrap;width:100%;box-sizing:border-box}.mw-parser-output .tmulti .tsingle{margin:1px;float:left}.mw-parser-output .tmulti .theader{clear:both;font-weight:bold;text-align:center;align-self:center;background-color:transparent;width:100%}.mw-parser-output .tmulti .thumbcaption{background-color:transparent}.mw-parser-output .tmulti .text-align-left{text-align:left}.mw-parser-output .tmulti .text-align-right{text-align:right}.mw-parser-output .tmulti .text-align-center{text-align:center}@media all and (max-width:720px){.mw-parser-output .tmulti .thumbinner{width:100%!important;box-sizing:border-box;max-width:none!important;align-items:center}.mw-parser-output .tmulti .trow{justify-content:center}.mw-parser-output .tmulti .tsingle{float:none!important;max-width:100%!important;box-sizing:border-box;text-align:center}.mw-parser-output .tmulti .tsingle .thumbcaption{text-align:left}.mw-parser-output .tmulti .trow>.thumbcaption{text-align:center}}</style><div class="thumb tmulti tright" about="#mwt17"><div class="thumbinner multiimageinner" style="width:204px;max-width:204px"><div class="trow"><div class="theader">Rules applied in simple Boids</div></div><div class="trow"><div class="tsingle" style="width:202px;max-width:202px"><div class="thumbimage"><span><a href="/en/File:Rule_separation.gif" class="mw-file-description image media-thumb" data-hash="File:Rule_separation.gif"><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e1/Rule_separation.gif/200px-Rule_separation.gif" decoding="async" data-file-width="217" data-file-height="145" data-file-type="bitmap" height="134" width="200" srcset="//upload.wikimedia.org/wikipedia/commons/e/e1/Rule_separation.gif 1.5x, //upload.wikimedia.org/wikipedia/commons/e/e1/Rule_separation.gif 2x" alt="Rule_separation.gif"></a></span></div><div class="thumbcaption">Separation</div></div></div><div class="trow"><div class="tsingle" style="width:202px;max-width:202px"><div class="thumbimage"><span><a href="/en/File:Rule_alignment.gif" class="mw-file-description image media-thumb" data-hash="File:Rule_alignment.gif"><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e1/Rule_alignment.gif/200px-Rule_alignment.gif" decoding="async" data-file-width="217" data-file-height="145" data-file-type="bitmap" height="134" width="200" srcset="//upload.wikimedia.org/wikipedia/commons/e/e1/Rule_alignment.gif 1.5x, //upload.wikimedia.org/wikipedia/commons/e/e1/Rule_alignment.gif 2x" alt="Rule_alignment.gif"></a></span></div><div class="thumbcaption">Alignment</div></div></div><div class="trow"><div class="tsingle" style="width:202px;max-width:202px"><div class="thumbimage"><span><a href="/en/File:Rule_cohesion.gif" class="mw-file-description image media-thumb" data-hash="File:Rule_cohesion.gif"><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/2/2b/Rule_cohesion.gif/200px-Rule_cohesion.gif" decoding="async" data-file-width="217" data-file-height="145" data-file-type="bitmap" height="134" width="200" srcset="//upload.wikimedia.org/wikipedia/commons/2/2b/Rule_cohesion.gif 1.5x, //upload.wikimedia.org/wikipedia/commons/2/2b/Rule_cohesion.gif 2x" alt="Rule_cohesion.gif"></a></span></div><div class="thumbcaption">Cohesion</div></div></div></div></div>
<div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none" about="#mwt1">Artificial life program</div>
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<figure class="mw-default-size wiki-thumb"><span><a href="/en/File:Boids_OpenGL_example.webm" class="app_media media-thumb" data-hash="File:Boids_OpenGL_example.webm"><video poster="//upload.wikimedia.org/wikipedia/commons/thumb/4/43/Boids_OpenGL_example.webm/220px--Boids_OpenGL_example.webm.jpg" preload="none" height="220" width="220" resource="./File:Boids_OpenGL_example.webm"><source src="//upload.wikimedia.org/wikipedia/commons/4/43/Boids_OpenGL_example.webm" type="video/webm; codecs=&quot;vp8&quot;" data-file-width="500" data-file-height="500" data-title="Original WebM file, 500 × 500 (1.96 Mbps)" data-shorttitle="WebM source"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/4/43/Boids_OpenGL_example.webm/Boids_OpenGL_example.webm.120p.vp9.webm" type="video/webm; codecs=&quot;vp9, opus&quot;" data-width="120" data-height="120" data-title="Lowest bandwidth VP9 (120P)" data-shorttitle="VP9 120P"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/4/43/Boids_OpenGL_example.webm/Boids_OpenGL_example.webm.160p.webm" type="video/webm; codecs=&quot;vp8, vorbis&quot;" data-width="160" data-height="160" data-title="Low bandwidth WebM (160P)" data-shorttitle="WebM 160P"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/4/43/Boids_OpenGL_example.webm/Boids_OpenGL_example.webm.180p.vp9.webm" type="video/webm; codecs=&quot;vp9, opus&quot;" data-width="180" data-height="180" data-title="Low bandwidth VP9 (180P)" data-shorttitle="VP9 180P"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/4/43/Boids_OpenGL_example.webm/Boids_OpenGL_example.webm.240p.vp9.webm" type="video/webm; codecs=&quot;vp9, opus&quot;" data-width="240" data-height="240" data-title="Small VP9 (240P)" data-shorttitle="VP9 240P"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/4/43/Boids_OpenGL_example.webm/Boids_OpenGL_example.webm.240p.webm" type="video/webm; codecs=&quot;vp8, vorbis&quot;" data-width="240" data-height="240" data-title="Small WebM (240P)" data-shorttitle="WebM 240P"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/4/43/Boids_OpenGL_example.webm/Boids_OpenGL_example.webm.360p.vp9.webm" type="video/webm; codecs=&quot;vp9, opus&quot;" data-width="360" data-height="360" data-title="VP9 (360P)" data-shorttitle="VP9 360P"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/4/43/Boids_OpenGL_example.webm/Boids_OpenGL_example.webm.360p.webm" type="video/webm; codecs=&quot;vp8, vorbis&quot;" data-width="360" data-height="360" data-title="WebM (360P)" data-shorttitle="WebM 360P"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/4/43/Boids_OpenGL_example.webm/Boids_OpenGL_example.webm.480p.vp9.webm" type="video/webm; codecs=&quot;vp9, opus&quot;" data-width="480" data-height="480" data-title="SD VP9 (480P)" data-shorttitle="VP9 480P"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/4/43/Boids_OpenGL_example.webm/Boids_OpenGL_example.webm.480p.webm" type="video/webm; codecs=&quot;vp8, vorbis&quot;" data-width="480" data-height="480" data-title="SD WebM (480P)" data-shorttitle="WebM 480P"></video></a></span><figcaption>A Boids example created in <a href="/en/OpenGL" title="OpenGL" class="wl">OpenGL</a></figcaption></figure>
<p>As with most artificial life simulations, Boids is an example of <a href="/en/Emergence" title="Emergence" class="wl">emergent</a> behavior; that is, the complexity of Boids arises from the interaction of individual agents (the boids, in this case) adhering to a set of simple rules.  The rules applied in the simplest Boids world are as follows:</p>
<ul><li><b>separation</b>: <a href="https://en.wiktionary.org/wiki/steer#Verb" title="wikt:steer" class="extiw" target="_blank">steer</a> to avoid crowding local flockmates</li>
<li><b>alignment</b>: steer towards the average heading of local flockmates</li>
<li><b>cohesion</b>: steer to move towards the average position (center of mass) of local flockmates</li></ul>

<p>More complex rules can be added, such as obstacle avoidance and goal seeking.</p>

<p>The basic model has been extended in several different ways since Reynolds proposed it. For instance, Delgado-Mata et<span>&nbsp;</span>al.<span class="mw-ref reference" id="cite_ref-3"><a href="#cite_note-3" style="counter-reset: mw-Ref 3;"><span class="mw-reflink-text">[3]</span></a></span> extended the basic model to incorporate the effects of fear. Olfaction was used to transmit emotion between animals, through pheromones modelled as particles in a free expansion gas. Hartman and Benes<span class="mw-ref reference" id="cite_ref-4"><a href="#cite_note-4" style="counter-reset: mw-Ref 4;"><span class="mw-reflink-text">[4]</span></a></span> introduced a complementary force to the alignment that they call the change of leadership. This steer defines the chance of the boid to become a leader and try to escape.</p>

<p>The movement of Boids can be characterized as either chaotic (splitting groups and wild behaviour) or orderly. Unexpected behaviours, such as splitting flocks and reuniting after avoiding obstacles, can be considered emergent.</p>

<p>The boids framework is often used in computer graphics, providing realistic-looking representations of flocks of birds and other creatures, such as schools of fish or herds of animals. It was for instance used in the 1998 video game <i><a href="/en/Half-Life_(video_game)" title="Half-Life (video game)" class="wl">Half-Life</a></i> for the flying bird-like creatures seen at the end of the game on <a href="/en/Locations_of_Half-Life#Xen" title="Locations of Half-Life" class="wl">Xen</a>, named "boid" in the game files.</p>

<p>The Boids model can be used for direct control and stabilization of teams of simple unmanned ground vehicles (UGV)<span class="mw-ref reference" id="cite_ref-5"><a href="#cite_note-5" style="counter-reset: mw-Ref 5;"><span class="mw-reflink-text">[5]</span></a></span> or <a href="/en/Micro_air_vehicle" title="Micro air vehicle" class="wl">micro aerial vehicles</a> (MAV)<span class="mw-ref reference" id="cite_ref-6"><a href="#cite_note-6" style="counter-reset: mw-Ref 6;"><span class="mw-reflink-text">[6]</span></a></span> in <a href="/en/Swarm_robotics" title="Swarm robotics" class="wl">swarm robotics</a>. For stabilization of heterogeneous UAV-UGV teams, the model was adapted for using onboard relative localization by Saska et<span>&nbsp;</span>al.<span class="mw-ref reference" id="cite_ref-7"><a href="#cite_note-7" style="counter-reset: mw-Ref 7;"><span class="mw-reflink-text">[7]</span></a></span></p>

<p>At the time of proposal, Reynolds' approach represented a giant step forward compared to the traditional techniques used in computer animation for motion pictures. The first animation created with the model was <i><a href="/en/Stanley_and_Stella_in:_Breaking_the_Ice" title="Stanley and Stella in: Breaking the Ice" class="wl">Stanley and Stella in: Breaking the Ice</a></i> (1987), followed by a feature film debut in <a href="/en/Tim_Burton" title="Tim Burton" class="wl">Tim Burton</a>'s film <i><a href="/en/Batman_Returns" title="Batman Returns" class="wl">Batman Returns</a></i> (1992) with computer generated bat swarms and armies of penguins marching through the streets of Gotham City.<span class="mw-ref reference" id="cite_ref-8"><a href="#cite_note-8" style="counter-reset: mw-Ref 8;"><span class="mw-reflink-text">[8]</span></a></span></p>

<p>The boids model has been used for other interesting applications. It has been applied to automatically program Internet multi-channel radio stations.<span class="mw-ref reference" id="cite_ref-9"><a href="#cite_note-9" style="counter-reset: mw-Ref 9;"><span class="mw-reflink-text">[9]</span></a></span> It has also been used for visualizing information<span class="mw-ref reference" id="cite_ref-10"><a href="#cite_note-10" style="counter-reset: mw-Ref 10;"><span class="mw-reflink-text">[10]</span></a></span> and for optimization tasks.<span class="mw-ref reference" id="cite_ref-11"><a href="#cite_note-11" style="counter-reset: mw-Ref 11;"><span class="mw-reflink-text">[11]</span></a></span></p>

<p>Biologist <a href="/en/Richard_Dawkins" title="Richard Dawkins" class="wl">Richard Dawkins</a> references the Boids model in his 2009 book <i><a href="/en/The_Greatest_Show_on_Earth:_The_Evidence_for_Evolution" title="The Greatest Show on Earth: The Evidence for Evolution" class="wl">The Greatest Show on Earth: The Evidence for Evolution</a></i>.<span class="mw-ref reference" id="cite_ref-12"><a href="#cite_note-12" style="counter-reset: mw-Ref 12;"><span class="mw-reflink-text">[12]</span></a></span></p>



Boids is an artificial life program, developed by Craig Reynolds in 1986, which simulates the flocking behaviour of birds. His paper on this topic was published in 1987 in the proceedings of the ACM SIGGRAPH conference. "Boid" is also a New York Metropolitan dialect pronunciation for "bird." As with most artificial life simulations, Boids is an example of emergent behavior; that is, the complexity of Boids arises from the interaction of individual agents adhering to a set of simple rules.  The rules applied in the simplest Boids world are as follows: More complex rules can be added, such as obstacle avoidance and goal seeking. 