Marker Implementation

Tutorial 2 of 4

Marker Implementation Tutorial

1. Introduction

In this tutorial, we aim to provide a thorough understanding of how to implement marker-based Augmented Reality (AR) using HTML. By the end of this tutorial, you will be able to create markers and use them to trigger AR content.

What you will learn:
- Understanding of Marker-based AR
- How to create markers
- How to trigger AR content using these markers

Prerequisites:
- Basic understanding of HTML and JavaScript
- Familiarity with AR concepts would be beneficial but not necessary

2. Step-by-Step Guide

Marker-based AR works by letting the software know what a specific marker looks like and what to do when it finds it. This usually involves overlaying digital images or 3D models on the marker in real-time.

Creating markers:
To create a marker, you can use a tool like AR.js Marker Training. This will output a pattern file and the marker image that you can use in your AR application.

Triggering AR content:
To trigger AR content, you'll need to use a JavaScript library like AR.js. You can include the library in your HTML file, define the marker, and specify what should be displayed when the marker is found.

3. Code Examples

Example 1: Displaying a 3D model when the marker is found

<html>
    <body style='margin : 0px; overflow: hidden;'>
        <script src='https://aframe.io/releases/0.9.2/aframe.min.js'></script>
        <script src='https://jeromeetienne.github.io/AR.js/aframe/build/aframe-ar.js'></script>
        <a-scene embedded arjs>
            <a-marker preset='custom' type='pattern' url='path/to/pattern-marker.patt'>
                <a-entity gltf-model='path/to/model.gltf'></a-entity>
            </a-marker>
            <a-entity camera></a-entity>
        </a-scene>
    </body>
</html>

In this example, we're including the A-Frame and AR.js libraries, which provide the functionality to display AR content. Within the a-marker element, we specify the type as 'pattern' and provide the URL to our pattern file. When this marker is found, the 3D model specified by the gltf-model attribute will be displayed.

4. Summary

In this tutorial, you've learned how to create markers for AR applications and use these markers to display AR content. The next step in your learning journey could be to explore different types of markers, such as barcode or matrix code markers. You could also learn how to create more complex AR content, like animated 3D models.

5. Practice Exercises

Exercise 1: Create a marker using the AR.js Marker Training tool and display a simple 3D model when the marker is found.

Hint: You can find free 3D models on websites like Google Poly.
Exercise 2: Extend the first exercise by animating the 3D model. You can do this by adding the animation component to the a-entity element.

Hint: The animation component allows you to specify properties like the attribute to animate, the to and from values, and the duration of the animation.
Exercise 3: Use a different type of marker, like a barcode marker, and display a different 3D model.

Hint: You can specify the type of marker by changing the type attribute of the a-marker element to 'barcode'.