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<h1>Introduction to AR.js and Natural Feature Tracking</h1>
<h2>AR.js</h2>
<p>AR.js is a lightweight library for Augmented Reality on the Web, coming with features like Image Tracking, Location based AR and Marker tracking. It is the easiest option for cross-browser augmented reality. </p>
<p>The same code works for iOS, Android, Desktops and even VR Browsers!</p>
<p>It was initially created by Jerome Etienne and is now maintained by Nicolo Carpignoli and the AR-js Organisation</p>
<h2>NFT</h2>
<p>Usually for augmented reality you need specialised markers, like this Hiro marker (notice the thick non-aesthetic borders 🤢)</p>
<p><img src="https://upload.wikimedia.org/wikipedia/commons/4/48/Hiro_marker_ARjs.png" alt="" /></p>
<p>This is called marker based tracking where the code knows what to look for. NFT or Natural Feature Tracing converts normal images into markers by extracting 'features' from it, this way you can use any image of your liking!</p>
<p>I'll be using my GitHub profile picture </p>
<p><img src="/images/me.jpeg" alt="" /></p>
<h2>Creating the Marker!</h2>
<p>First we need to create the marker files required by AR.js for NFT. For this we use Carnaux's repository 'NFT-Marker-Creator'.</p>
<pre><code>$ git clone https://github.com/Carnaux/NFT-Marker-Creator
Cloning into 'NFT-Marker-Creator'...
remote: Enumerating objects: 79, done.
remote: Counting objects: 100% (79/79), done.
remote: Compressing objects: 100% (72/72), done.
remote: Total 580 (delta 10), reused 59 (delta 7), pack-reused 501
Receiving objects: 100% (580/580), 9.88 MiB | 282.00 KiB/s, done.
Resolving deltas: 100% (262/262), done.
$ cd NFT-Makrer-Creator
</code></pre>
<h3>Install the dependencies</h3>
<pre><code>$ npm install
npm WARN nodegenerator@1.0.0 No repository field.
added 67 packages from 56 contributors and audited 67 packages in 2.96s
1 package is looking for funding
run `npm fund` for details
found 0 vulnerabilities
╭────────────────────────────────────────────────────────────────╮
│ │
│ New patch version of npm available! 6.14.5 → 6.14.7 │
│ Changelog: https://github.com/npm/cli/releases/tag/v6.14.7 │
│ Run npm install -g npm to update! │
│ │
╰────────────────────────────────────────────────────────────────╯
</code></pre>
<h3>Copy the target marker to the folder</h3>
<pre><code>$ cp ~/CodingAndStuff/ARjs/me.png .
</code></pre>
<h3>Generate Marker</h3>
<pre><code>$ node app.js -i me.png
Confidence level: [ * * * * * ] 5/5 || Entropy: 5.24 || Current max: 5.17 min: 4.6
Do you want to continue? (Y/N)
y
writeStringToMemory is deprecated and should not be called! Use stringToUTF8() instead!
[info]
Commands:
[info] --
Generator started at 2020-08-01 16:01:41 +0580
[info] Tracking Extraction Level = 2
[info] MAX_THRESH = 0.900000
[info] MIN_THRESH = 0.550000
[info] SD_THRESH = 8.000000
[info] Initialization Extraction Level = 1
[info] SURF_FEATURE = 100
[info] min allow 3.699000.
[info] Image DPI (1): 3.699000
[info] Image DPI (2): 4.660448
[info] Image DPI (3): 5.871797
[info] Image DPI (4): 7.398000
[info] Image DPI (5): 9.320896
[info] Image DPI (6): 11.743593
[info] Image DPI (7): 14.796000
[info] Image DPI (8): 18.641792
[info] Image DPI (9): 23.487186
[info] Image DPI (10): 29.592001
[info] Image DPI (11): 37.283585
[info] Image DPI (12): 46.974373
[info] Image DPI (13): 59.184002
[info] Image DPI (14): 72.000000
[info] Generating ImageSet...
[info] (Source image xsize=568, ysize=545, channels=3, dpi=72.0).
[info] Done.
[info] Saving to asa.iset...
[info] Done.
[info] Generating FeatureList...
...
[info] (46, 44) 5.871797[dpi]
[info] Freak features - 23[info] ========= 23 ===========
[info] (37, 35) 4.660448[dpi]
[info] Freak features - 19[info] ========= 19 ===========
[info] (29, 28) 3.699000[dpi]
[info] Freak features - 9[info] ========= 9 ===========
[info] Done.
[info] Saving FeatureSet3...
[info] Done.
[info] Generator finished at 2020-08-01 16:02:02 +0580
--
Finished marker creation!
Now configuring demo!
Finished!
To run demo use: 'npm run demo'
</code></pre>
<p>Now we have the required files in the output folder</p>
<pre><code>$ ls output
me.fset me.fset3 me.iset
</code></pre>
<h2>Creating the HTML Page</h2>
<p>Create a new file called <code>index.html</code> in your project folder. This is the basic template we are going to use. Replace <code>me</code> with the root filename of your image, for example <code>NeverGonnaGiveYouUp.png</code> will become <code>NeverGonnaGiveYouUp</code>. Make sure you have copied all three files from the output folder in the previous step to the root of your project folder.</p>
<div class="codehilite"><pre><span></span><code><span class="p"><</span><span class="nt">script</span> <span class="na">src</span><span class="o">=</span><span class="s">"https://cdn.jsdelivr.net/gh/aframevr/aframe@1c2407b26c61958baa93967b5412487cd94b290b/dist/aframe-master.min.js"</span><span class="p">></</span><span class="nt">script</span><span class="p">></span>
<span class="p"><</span><span class="nt">script</span> <span class="na">src</span><span class="o">=</span><span class="s">"https://raw.githack.com/AR-js-org/AR.js/master/aframe/build/aframe-ar-nft.js"</span><span class="p">></</span><span class="nt">script</span><span class="p">></span>
<span class="p"><</span><span class="nt">style</span><span class="p">></span>
<span class="p">.</span><span class="nc">arjs-loader</span> <span class="p">{</span>
<span class="k">height</span><span class="p">:</span> <span class="mi">100</span><span class="kt">%</span><span class="p">;</span>
<span class="k">width</span><span class="p">:</span> <span class="mi">100</span><span class="kt">%</span><span class="p">;</span>
<span class="k">position</span><span class="p">:</span> <span class="kc">absolute</span><span class="p">;</span>
<span class="k">top</span><span class="p">:</span> <span class="mi">0</span><span class="p">;</span>
<span class="k">left</span><span class="p">:</span> <span class="mi">0</span><span class="p">;</span>
<span class="k">background-color</span><span class="p">:</span> <span class="nb">rgba</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mf">0.8</span><span class="p">);</span>
<span class="k">z-index</span><span class="p">:</span> <span class="mi">9999</span><span class="p">;</span>
<span class="k">display</span><span class="p">:</span> <span class="kc">flex</span><span class="p">;</span>
<span class="k">justify-content</span><span class="p">:</span> <span class="kc">center</span><span class="p">;</span>
<span class="k">align-items</span><span class="p">:</span> <span class="kc">center</span><span class="p">;</span>
<span class="p">}</span>
<span class="p">.</span><span class="nc">arjs-loader</span> <span class="nt">div</span> <span class="p">{</span>
<span class="k">text-align</span><span class="p">:</span> <span class="kc">center</span><span class="p">;</span>
<span class="k">font-size</span><span class="p">:</span> <span class="mf">1.25</span><span class="kt">em</span><span class="p">;</span>
<span class="k">color</span><span class="p">:</span> <span class="kc">white</span><span class="p">;</span>
<span class="p">}</span>
<span class="p"></</span><span class="nt">style</span><span class="p">></span>
<span class="p"><</span><span class="nt">body</span> <span class="na">style</span><span class="o">=</span><span class="s">"margin : 0px; overflow: hidden;"</span><span class="p">></span>
<span class="p"><</span><span class="nt">div</span> <span class="na">class</span><span class="o">=</span><span class="s">"arjs-loader"</span><span class="p">></span>
<span class="p"><</span><span class="nt">div</span><span class="p">></span>Calculating Image Descriptors....<span class="p"></</span><span class="nt">div</span><span class="p">></span>
<span class="p"></</span><span class="nt">div</span><span class="p">></span>
<span class="p"><</span><span class="nt">a-scene</span>
<span class="na">vr-mode-ui</span><span class="o">=</span><span class="s">"enabled: false;"</span>
<span class="na">renderer</span><span class="o">=</span><span class="s">"logarithmicDepthBuffer: true;"</span>
<span class="na">embedded</span>
<span class="na">arjs</span><span class="o">=</span><span class="s">"trackingMethod: best; sourceType: webcam;debugUIEnabled: false;"</span>
<span class="p">></span>
<span class="p"><</span><span class="nt">a-nft</span>
<span class="na">type</span><span class="o">=</span><span class="s">"nft"</span>
<span class="na">url</span><span class="o">=</span><span class="s">"./me"</span>
<span class="na">smooth</span><span class="o">=</span><span class="s">"true"</span>
<span class="na">smoothCount</span><span class="o">=</span><span class="s">"10"</span>
<span class="na">smoothTolerance</span><span class="o">=</span><span class="s">".01"</span>
<span class="na">smoothThreshold</span><span class="o">=</span><span class="s">"5"</span>
<span class="p">></span>
<span class="p"></</span><span class="nt">a-nft</span><span class="p">></span>
<span class="p"><</span><span class="nt">a-entity</span> <span class="na">camera</span><span class="p">></</span><span class="nt">a-entity</span><span class="p">></span>
<span class="p"></</span><span class="nt">a-scene</span><span class="p">></span>
<span class="p"></</span><span class="nt">body</span><span class="p">></span>
</code></pre></div>
<p>In this we are creating a AFrame scene and we are telling it that we want to use NFT Tracking. The amazing part about using AFrame is that we are able to use all AFrame objects!</p>
<h2>Adding a simple box</h2>
<p>Let us add a simple box!</p>
<div class="codehilite"><pre><span></span><code><span class="p"><</span><span class="nt">a-nft</span> <span class="err">.....</span><span class="p">></span>
<span class="p"><</span><span class="nt">a-box</span> <span class="na">position</span><span class="o">=</span><span class="s">'100 0.5 -180'</span> <span class="na">material</span><span class="o">=</span><span class="s">'opacity: 0.5; side: double'</span> <span class="na">scale</span><span class="o">=</span><span class="s">"100 100 100"</span><span class="p">></</span><span class="nt">a-box</span><span class="p">></span>
<span class="p"></</span><span class="nt">a-nft</span><span class="p">></span>
</code></pre></div>
<p>Now to test it out we will need to create a simple server, I use Python's inbuilt <code>SimpleHTTPServer</code> alongside <code>ngrok</code> </p>
<p>In one terminal window, <code>cd</code> to the project directory. Currently your project folder should have 4 files, <code>index.html</code>, <code>me.fset3</code>, <code>me.fset</code> and <code>me.iset</code></p>
<p>Open up two terminal windows and <code>cd</code> into your project folder then run the following commands to start up your server.</p>
<p>In the first terminal window start the Python Server</p>
<pre><code>$ cd ~/CodingAndStuff/ARjs
$ python2 -m SimpleHTTPServer
Serving HTTP on 0.0.0.0 port 8000 ...
</code></pre>
<p>In the other window run <code>ngrok</code> ( Make sure you have installed it prior to running this step )</p>
<pre><code>$ ngrok http 8000
</code></pre>
<p><img src="/assets/posts/arjs/01-ngrok.png" alt="" /></p>
<p>Now copy the url to your phone and try running the example </p>
<p><img src="/assets/posts/arjs/02-box-demo.gif" alt="" /></p>
<p>👏 Congratulations! You just built an Augmented Reality experience using AR.js and AFrame</p>
<h2>Adding a Torus-Knot in the box</h2>
<p>Edit your <code>index.html</code> </p>
<div class="codehilite"><pre><span></span><code><span class="p"><</span><span class="nt">a-nft</span> <span class="err">..</span><span class="p">></span>
<span class="p"><</span><span class="nt">a-box</span> <span class="err">..</span><span class="p">></span>
<span class="p"><</span><span class="nt">a-torus-knot</span> <span class="na">radius</span><span class="o">=</span><span class="s">'0.26'</span> <span class="na">radius-tubular</span><span class="o">=</span><span class="s">'0.05'</span> <span class="p">></</span><span class="nt">a-torus-knot</span><span class="p">></span>
<span class="p"></</span> <span class="nt">a-box</span><span class="p">></span>
<span class="p"></</span> <span class="nt">a-nft</span><span class="p">></span>
</code></pre></div>
<p><img src="/assets/posts/arjs/03-knot.png" alt="" /></p>
<h2>Where are the GIFs?</h2>
<p>Now that we know how to place a box in the scene and add a torus knot in it, what do we do next? We bring the classic internet back!</p>
<p><code>AFrame GIF Shader</code> is a gif shader for A-Frame created by mayognaise.</p>
<h3>First things first</h3>
<p>Add <code><script src="https://rawgit.com/mayognaise/aframe-gif-shader/master/dist/aframe-gif-shader.min.js"></script></code> to <code><head></code></p>
<p>Change the box's material to add the GIF shader</p>
<div class="codehilite"><pre><span></span><code>...
<span class="p"><</span><span class="nt">a-box</span> <span class="na">position</span><span class="o">=</span><span class="s">'100 0.5 -180'</span> <span class="na">material</span><span class="o">=</span><span class="s">"shader:gif;src:url(https://media.tenor.com/images/412b1aa9149d98d561df62db221e0789/tenor.gif);opacity:.5"</span> <span class="err">.....</span><span class="p">></span>
</code></pre></div>
<p><img src="/assets/posts/arjs/04-nyan.gif" alt="" /></p>
<h2>Bonus Idea: Integrate it with GitHub's new profile Readme Feature!</h2>
<h3>1) Host the code using GitHub Pages</h3>
<h3>2) Create a new repository ( the name should be your GitHub username )</h3>
<h3>3) Add QR Code to the page and tell the users to scan your profile picture</h3>
<h3>??) Profit 💸</h3>
<p>Here is a screenshot of me scanning a rounded version of my profile picture ( It still works! Even though the image is cropped and I haven't changed any line of code )</p>
<p><img src="/assets/posts/arjs/05-GitHub.jpg" alt="" /></p>
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