Basics of AR: SLAM – Simultaneous Localization and Mapping

How HoloLens sees the World

In the first part, we took a look at how an algorithm identifies keypoints in camera frames. These are the base for tracking & recognizing the environment.

For Augmented Reality, the device has to know more: its 3D position in the world. It calculates this through the spatial relationship between itself and multiple keypoints. This process is called “Simultaneous Localization and Mapping” – SLAM for short.

Sensors for Perceiving the World

The high-level view: when you first start an AR app using Google ARCore, Apple ARKit or Microsoft Mixed Reality, the system doesn’t know much about the environment. It starts processing data from various sources – mostly the camera. To improve accuracy, the device combines data from other useful sensors like the accelerometer and the gyroscope.

Based on this data, the algorithm has two aims:

  1. Build a map of the environment
  2. Locate the device within that environment
Continue reading “Basics of AR: SLAM – Simultaneous Localization and Mapping”

Basics of AR: Anchors, Keypoints & Feature Detection

Detected Anchors by Google ARCore

Creating apps that work well with Augmented Reality requires some background knowledge of the image processing algorithms that work behind the scenes. One of the most fundamental concepts involves anchors. These rely on keypoints and their descriptors, detected in the recording of the real world.

Anchor Virtual Objects to the Real World

AR development APIs hide much of the complexity. As a developer, you simply anchor virtual objects to the world. This ensures that the hologram stays glued to the physical location where you put it. Continue reading “Basics of AR: Anchors, Keypoints & Feature Detection”

How to Record a Video from a Unity ARCore App on Android

ARCore Recorded Video converted to an Animated GIF

A video is a great way to showcase your Unity app. To capture the full visual fidelity of your app, you need to record at the highest possible quality with a smooth frame rate.

Several screen recording apps are available in the Google Play Store. However, there’s an easy and completely free way that provides the highest possible quality.

This short guide demonstrates how to record the screen with an APK file generated by Unity. Of course, it works for both AR and Non-AR Apps. Continue reading “How to Record a Video from a Unity ARCore App on Android”

Remote ARCore with Unity’s Experimental ARInterface

Overall, the AR ecosystem is still small. Nevertheless, it’s fragmented. Google develops ARCore, Apple creates ARKit and Microsoft is working on the Mixed Reality Toolkit. Fortunately, Unity started unifying these APIs with the ARInterface.

At Unite Austin, two of the Unity engineers introduced the new experimental ARInterface. In November 2017, they released it to the public via GitHub. It looks like this will be integrated into Unity 2018 – the new features of Unity 2018.1 include “AR Crossplatfom Kit (ARCore/ARKit API)“.

Remote Testing of AR Apps

The traditional mobile AR app development cycle includes compiling and deploying apps to a real device. That takes a long time and is tedious for quick testing iterations.

A big advantage of ARKit so far has been the ARKit Unity Remote feature. The iPhone runs a simple “tracking” app. It transmits its captured live data to the PC. Your actual AR app is running directly in the Unity Editor on the PC, based on the data it gets from the device. Through this approach, you can run the app by simply pressing the Play-button in Unity, without native compilation.

This is similar to the Holographic Emulation for the Microsoft HoloLens, which has been available for Unity for some time.

The great news is that the new Unity ARInterface finally adds a similar feature to Google ARCore: ARRemoteInterface. It’s available cross-platform for ARKit and ARCore.

ARInterface Demo App

In this article, I’ll explain the steps to get AR Remote running on Google ARCore. For reference: “Pirates Just AR” also posted a helpful short video on YouTube. Continue reading “Remote ARCore with Unity’s Experimental ARInterface”

NFC Tags, NDEF and Android (with Kotlin)

Android: Launch App through NFC Tags

In this article, you will learn how to add NFC tag reading to an Android app. It registers for auto-starting when the user taps a specific NDEF NFC tag with the phone. In addition, the app reads the NDEF records from the tag.

NFC & NDEF

Apple added support for reading NFC tags with iOS 11 in September 2017. All iPhones starting with the iPhone 7 offer an API to read NFC tags. While Android included NFC support for many years, this was the final missing piece to bring NFC tag scenarios to the masses. Continue reading “NFC Tags, NDEF and Android (with Kotlin)”

How To: RecyclerView with a Kotlin-Style Click Listener in Android

Android RecyclerView - Click Listener - Flow

In this article, we add a click listener to a RecyclerView on Android. Advanced language features of Kotlin make it far easier than it has been with Java. However, you need to understand a few core concepts of the Kotlin language.

To get started with the RecyclerView, follow the steps in the previous article or check out the finished project on GitHub. Continue reading “How To: RecyclerView with a Kotlin-Style Click Listener in Android”

Kotlin & RecyclerView for High Performance Lists in Android

Android: RecyclerView - Adapter Flow

RecyclerView is the best approach to show scrolling lists on Android. It ensures high performance & smooth scrolling, while providing list elements with flexible layouts. Combined with modern language features of Kotlin, the code overhead of the RecyclerView is greatly reduced compared to the traditional Java approach.

Sample Project: PartsList – Getting Started

In this article, we’ll walk through a sample scenario: a scrolling list for a maintenance app, listing machine parts: “PartsList”. However, this scenario only affects the strings we use – you can copy this approach for any use case you need. Continue reading “Kotlin & RecyclerView for High Performance Lists in Android”

Augmented Reality Christmas Tree with Google ARCore Developer Preview 2 – in 5 Minutes

Christmas Tree with Google ARCore

We don’t have a Christmas tree in our apartment. But in today’s world, this is what Augmented Reality is for, right? Therefore, I decided to create an AR Christmas Tree in 5 minutes. This also gave me an opportunity to check out the new Google ARCore Developer Preview 2.

Christmas Tree 3D Model

First off, you need a 3D model of a Christmas tree. Two of the most accessible sources are Google Poly and Microsoft Remix 3D. Sticking to models created directly by Google and Microsoft, these two are the choices:

Christmas Tree by Poly by Google
Christmas Tree by Poly by Google

Continue reading “Augmented Reality Christmas Tree with Google ARCore Developer Preview 2 – in 5 Minutes”

Real-Time Light Estimation with Google ARCore

ARCore: Light Estimation is an average of the overall image luminosity

ARCore has a great feature – light estimation. The ARCore SDK estimates the global lighting, which you can use as input for your own shaders to make the virtual objects fit in better with the captured real world. In this article, I’m taking a closer look at how the light estimation works in the current ARCore preview SDK.

Note: this article is based on the ARCore developer preview 1. Some details changed in the developer preview 2 – although the generic process is still similar. Continue reading “Real-Time Light Estimation with Google ARCore”

Getting Started with Google ARCore, Part 2: Visualizing Planes & Placing Objects

Models of Brains (segmented from an an MRI) placed in the real world using Google ARCore

Following the basic project setup of the first part of this article, we now get to the fascinating details of the ARCore SDK. Learn how to find and visualize planes. Additionally, I’ll show how to instantiate objects and how to anchor them to the real world using Unity.

Finding Planes with ARCore

The ARCore example contains a simple script to visualize planes, point clouds and to place the Android mascot. We’ll create a shorter version of the script here. Continue reading “Getting Started with Google ARCore, Part 2: Visualizing Planes & Placing Objects”