Search icon CANCEL
Subscription
0
Cart icon
Your Cart (0 item)
Close icon
You have no products in your basket yet
Arrow left icon
Explore Products
Best Sellers
New Releases
Books
Videos
Audiobooks
Learning Hub
Free Learning
Arrow right icon
Mastering OpenCV with Practical Computer Vision Projects
Mastering OpenCV with Practical Computer Vision Projects

Mastering OpenCV with Practical Computer Vision Projects: This is the definitive advanced tutorial for OpenCV, designed for those with basic C++ skills. The computer vision projects are divided into easily assimilated chapters with an emphasis on practical involvement for an easier learning curve.

eBook
₹799.99 ₹2919.99
Paperback
₹3649.99
Subscription
Free Trial
Renews at ₹800p/m

What do you get with a Packt Subscription?

Free for first 7 days. ₹800 p/m after that. Cancel any time!
Product feature icon Unlimited ad-free access to the largest independent learning library in tech. Access this title and thousands more!
Product feature icon 50+ new titles added per month, including many first-to-market concepts and exclusive early access to books as they are being written.
Product feature icon Innovative learning tools, including AI book assistants, code context explainers, and text-to-speech.
Product feature icon Thousands of reference materials covering every tech concept you need to stay up to date.
Subscribe now
View plans & pricing
Table of content icon View table of contents Preview book icon Preview Book

Mastering OpenCV with Practical Computer Vision Projects

Chapter 2. Marker-based Augmented Reality on iPhone or iPad

Augmented reality (AR) is a live view of a real-world environment whose elements are augmented by computer-generated graphics. As a result, the technology functions by enhancing one's current perception of reality. Augmentation is conventionally in real-time and in semantic context with environmental elements. With the help of advanced AR technology (for example, adding computer vision and object recognition) the information about the surrounding real world of the user becomes interactive and can be digitally manipulated. Artificial information about the environment and its objects can be overlaid on the real world.

In this chapter we will create an AR application for iPhone/iPad devices. Starting from scratch, we will create an application that uses markers to draw some artificial objects on the images acquired from the camera. You will learn how to set up a project in XCode IDE and configure it to use OpenCV within your application...

Creating an iOS project that uses OpenCV


In this section we will create a demo application for iPhone/iPad devices that will use the OpenCV (Open Source Computer Vision) library to detect markers in the camera frame and render 3D objects on it. This example will show you how to get access to the raw video data stream from the device camera, perform image processing using the OpenCV library, find a marker in an image, and render an AR overlay.

We will start by first creating a new XCode project by choosing the iOS Single View Application template, as shown in the following screenshot:

Now we have to add OpenCV to our project. This step is necessary because in this application we will use a lot of functions from this library to detect markers and estimate position position.

OpenCV is a library of programming functions for real-time computer vision. It was originally developed by Intel and is now supported by Willow Garage and Itseez. This library is written in C and C++ languages. It also has...

Application architecture


Each iOS application contains at least one instance of the UIViewController interface that handles all view events and manages the application's business logic. This class provides the fundamental view-management model for all iOS apps. A view controller manages a set of views that make up a portion of your app's user interface. As part of the controller layer of your app, a view controller coordinates its efforts with model objects and other controller objects—including other view controllers—so your app presents a single coherent user interface.

The application that we are going to write will have only one view; that's why we choose a Single-View Application template to create one. This view will be used to present the rendered picture. Our ViewController class will contain three major components that each AR application should have (see the next diagram):

  • Video source

  • Processing pipeline

  • Visualization engine

The video source is responsible for providing new frames...

Marker detection


A marker is usually designed as a rectangle image holding black and white areas inside it. Due to known limitations, the marker detection procedure is a simple one. First of all we need to find closed contours on the input image and unwarp the image inside it to a rectangle and then check this against our marker model.

In this sample the 5 x 5 marker will be used. Here is what it looks like:

In the sample project that you will find in this book, the marker detection routine is encapsulated in the MarkerDetector class:

/**
 * A top-level class that encapsulate marker detector algorithm
 */
class MarkerDetector
{
public:
  
  /**
   * Initialize a new instance of marker detector object
   * @calibration[in] - Camera calibration necessary for pose estimation.
   */
  MarkerDetector(CameraCalibration calibration);
  
  void processFrame(const BGRAVideoFrame& frame);
  
  const std::vector<Transformation>& getTransformations() const;
  
  protected:
  bool findMarkers...

Placing a marker in 3D


Augmented Reality tries to fuse the real-world object with virtual content. To place a 3D model in a scene, we need to know its pose with regard to a camera that we use to obtain the video frames. We will use a Euclidian transformation in the Cartesian coordinate system to represent such a pose.

The position of the marker in 3D and its corresponding projection in 2D is restricted by the following equation:

P = A * [R|T] * M;

Where:

  • M denotes a point in a 3D space

  • [R|T] denotes a [3|4] matrix representing a Euclidian transformation

  • A denotes a camera matrix or a matrix of intrinsic parameters

  • P denotes projection of M in screen space

After performing the marker detection step we now know the position of the four marker corners in 2D (projections in screen space). In the next section you will learn how to obtain the A matrix and M vector parameters and calculate the [R|T] transformation.

Camera calibration

Each camera lens has unique parameters, such as focal length, principal...

Rendering the 3D virtual object


So, by now you already know how to find the markers on the image to calculate their exact position in space, relative to the camera. It's time to draw something. As already mentioned, to render the scene we will use OpenGL functions. 3D visualization is a core part of Augmented Reality. OpenGL provides all the basic features for creating high-quality rendering.

Note

There are a large number of commercial and open source 3D-engines (Unity, Unreal Engine, Ogre, and so on). But all these engines use either OpenGL or DirectX to pass commands to the video card. DirectX is a proprietary API and it's supported only on the Windows platform. For this reason, OpenGL is the first and last candidate for building cross-platform rendering systems.

Understanding the principles of the rendering system will give you the necessary experience and knowledge to use these engines in the future or to write your own.

Creating the OpenGL rendering layer

In order to use OpenGL functions...

Summary


In this chapter we learned how to create a mobile Augmented Reality application for iPhone/iPad devices. You gained knowledge on how to use the OpenCV library within the XCode projects to create stunning state-of-the-art applications. Usage of OpenCV enables your application to perform complex image processing computations on mobile devices with real-time performance.

From this chapter you also learned how to perform the initial image processing (translation in shades of gray and binarization), how to find closed contours in the image and approximate them with polygons, how to find markers in the image and decode them, how to compute the marker position in space, and the visualization of 3D objects in Augmented Reality.

References


Left arrow icon Right arrow icon

Key benefits

  • Allows anyone with basic OpenCV experience to rapidly obtain skills in many computer vision topics, for research or commercial use
  • Each chapter is a separate project covering a computer vision problem, written by a professional with proven experience on that topic
  • All projects include a step-by-step tutorial and full source-code, using the C++ interface of OpenCV

Description

Computer Vision is fast becoming an important technology and is used in Mars robots, national security systems, automated factories, driver-less cars, and medical image analysis to new forms of human-computer interaction. OpenCV is the most common library for computer vision, providing hundreds of complex and fast algorithms. But it has a steep learning curve and limited in-depth tutorials.Mastering OpenCV with Practical Computer Vision Projects is the perfect book for developers with just basic OpenCV skills who want to try practical computer vision projects, as well as the seasoned OpenCV experts who want to add more Computer Vision topics to their skill set or gain more experience with OpenCV's new C++ interface before migrating from the C API to the C++ API.Each chapter is a separate project including the necessary background knowledge, so try them all one-by-one or jump straight to the projects you're most interested in.Create working prototypes from this book including real-time mobile apps, Augmented Reality, 3D shape from video, or track faces & eyes, fluid wall using Kinect, number plate recognition and so on. Mastering OpenCV with Practical Computer Vision Projects gives you rapid training in nine computer vision areas with useful projects.

Who is this book for?

You should have basic OpenCV and C/C++ programming experience before reading this book, as it is aimed at Computer Science graduates, researchers, and computer vision experts widening their expertise.

What you will learn

  • Perform Face Analysis including simple Face & Eye & Skin Detection, Fisherfaces Face Recognition, 3D Head Orientation, complex Facial Feature Tracking.
  • Do Number Plate Detection and Optical Character Recognition (OCR) using Artificial Intelligence (AI) methods including SVMs and Neural Networks
  • Learn Augmented Reality for desktop and iPhone or iPad using simple artificial markers or complex markerless natural images
  • Generate a 3D object model by moving a plain 2D camera, using 3D Structure from Motion (SfM) camera reprojection methods
  • Redesign desktop real-time computer vision applications to more suitable Android & iOS mobile apps
  • Use simple image filter effects including cartoon, sketch, paint, and alien effects
  • Execute Human-Computer Interaction with an XBox Kinect sensor using the whole body as a dynamic input

Product Details

Country selected
Publication date, Length, Edition, Language, ISBN-13
Publication date : Dec 03, 2012
Length: 340 pages
Edition : 1st
Language : English
ISBN-13 : 9781849517829
Category :
Languages :
Tools :

What do you get with a Packt Subscription?

Free for first 7 days. ₹800 p/m after that. Cancel any time!
Product feature icon Unlimited ad-free access to the largest independent learning library in tech. Access this title and thousands more!
Product feature icon 50+ new titles added per month, including many first-to-market concepts and exclusive early access to books as they are being written.
Product feature icon Innovative learning tools, including AI book assistants, code context explainers, and text-to-speech.
Product feature icon Thousands of reference materials covering every tech concept you need to stay up to date.
Subscribe now
View plans & pricing

Product Details

Publication date : Dec 03, 2012
Length: 340 pages
Edition : 1st
Language : English
ISBN-13 : 9781849517829
Category :
Languages :
Tools :

Packt Subscriptions

See our plans and pricing
Modal Close icon
₹800 billed monthly
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Simple pricing, no contract
₹4500 billed annually
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Choose a DRM-free eBook or Video every month to keep
Feature tick icon PLUS own as many other DRM-free eBooks or Videos as you like for just ₹400 each
Feature tick icon Exclusive print discounts
₹5000 billed in 18 months
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Choose a DRM-free eBook or Video every month to keep
Feature tick icon PLUS own as many other DRM-free eBooks or Videos as you like for just ₹400 each
Feature tick icon Exclusive print discounts

Frequently bought together


Stars icon
Total 9,459.97
Mastering OpenCV with Practical Computer Vision Projects
₹3649.99
OpenCV Essentials
₹2159.99
OpenCV Computer Vision Application Programming Cookbook Second Edition
₹3649.99
Total 9,459.97 Stars icon
Banner background image

Table of Contents

8 Chapters
Cartoonifier and Skin Changer for Android Chevron down icon Chevron up icon
Marker-based Augmented Reality on iPhone or iPad Chevron down icon Chevron up icon
Marker-less Augmented Reality Chevron down icon Chevron up icon
Exploring Structure from Motion Using OpenCV Chevron down icon Chevron up icon
Number Plate Recognition Using SVM and Neural Networks Chevron down icon Chevron up icon
Non-rigid Face Tracking Chevron down icon Chevron up icon
3D Head Pose Estimation Using AAM and POSIT Chevron down icon Chevron up icon
Face Recognition using Eigenfaces or Fisherfaces Chevron down icon Chevron up icon

Customer reviews

Top Reviews
Rating distribution
Full star icon Full star icon Full star icon Full star icon Half star icon 4.2
(17 Ratings)
5 star 35.3%
4 star 58.8%
3 star 0%
2 star 5.9%
1 star 0%
Filter icon Filter
Top Reviews

Filter reviews by




Marco Jul 20, 2013
Full star icon Full star icon Full star icon Full star icon Full star icon 5
Wirklich gute Beispiele, hervorragendes Praxisbuch! Genau was man braucht um zu Arbeiten - keine überflüssigen Abschriften von Hilfedateien oder Funktionsbeschreibungen sondern praxisnahe Beispiele an denen man sich orientieren kann
Amazon Verified review Amazon
Sreejith.M Jan 29, 2017
Full star icon Full star icon Full star icon Full star icon Full star icon 5
One of the best book to learn opencv and computer vision. Highly recommended
Amazon Verified review Amazon
Amazon Customer Sep 03, 2013
Full star icon Full star icon Full star icon Full star icon Full star icon 5
A person, totally unaware of CV or image processing have created an AR application for iOS for a week. IMHO, incredible.
Amazon Verified review Amazon
Jose I. Miranda Nov 29, 2013
Full star icon Full star icon Full star icon Full star icon Full star icon 5
This is the book I was looking for advanced projects with OpenCV 2. Really. It brings the best related to the most recent issues on face and character recognition.
Amazon Verified review Amazon
Kevin Feb 26, 2014
Full star icon Full star icon Full star icon Full star icon Full star icon 5
Of all the book reviews I’ve done this is the most genuine because I actually found this book useful for work I was doing. They found the right level of being technically interesting, robust and substantial all the while without being too daunting. The source code that accompanies this book is great and I still check back to it when starting new projects ([...]). Its well written and won’t take long to read through – I think it is a worthwhile read for anyone doing computer vision work. Program design isn’t something a lot of computer vision researchers / developers think or talk about a lot (at least in my experience) so to see how others lay out the problem can really help with your own work.
Amazon Verified review Amazon
Get free access to Packt library with over 7500+ books and video courses for 7 days!
Start Free Trial

FAQs

What is included in a Packt subscription? Chevron down icon Chevron up icon

A subscription provides you with full access to view all Packt and licnesed content online, this includes exclusive access to Early Access titles. Depending on the tier chosen you can also earn credits and discounts to use for owning content

How can I cancel my subscription? Chevron down icon Chevron up icon

To cancel your subscription with us simply go to the account page - found in the top right of the page or at https://subscription.packtpub.com/my-account/subscription - From here you will see the ‘cancel subscription’ button in the grey box with your subscription information in.

What are credits? Chevron down icon Chevron up icon

Credits can be earned from reading 40 section of any title within the payment cycle - a month starting from the day of subscription payment. You also earn a Credit every month if you subscribe to our annual or 18 month plans. Credits can be used to buy books DRM free, the same way that you would pay for a book. Your credits can be found in the subscription homepage - subscription.packtpub.com - clicking on ‘the my’ library dropdown and selecting ‘credits’.

What happens if an Early Access Course is cancelled? Chevron down icon Chevron up icon

Projects are rarely cancelled, but sometimes it's unavoidable. If an Early Access course is cancelled or excessively delayed, you can exchange your purchase for another course. For further details, please contact us here.

Where can I send feedback about an Early Access title? Chevron down icon Chevron up icon

If you have any feedback about the product you're reading, or Early Access in general, then please fill out a contact form here and we'll make sure the feedback gets to the right team. 

Can I download the code files for Early Access titles? Chevron down icon Chevron up icon

We try to ensure that all books in Early Access have code available to use, download, and fork on GitHub. This helps us be more agile in the development of the book, and helps keep the often changing code base of new versions and new technologies as up to date as possible. Unfortunately, however, there will be rare cases when it is not possible for us to have downloadable code samples available until publication.

When we publish the book, the code files will also be available to download from the Packt website.

How accurate is the publication date? Chevron down icon Chevron up icon

The publication date is as accurate as we can be at any point in the project. Unfortunately, delays can happen. Often those delays are out of our control, such as changes to the technology code base or delays in the tech release. We do our best to give you an accurate estimate of the publication date at any given time, and as more chapters are delivered, the more accurate the delivery date will become.

How will I know when new chapters are ready? Chevron down icon Chevron up icon

We'll let you know every time there has been an update to a course that you've bought in Early Access. You'll get an email to let you know there has been a new chapter, or a change to a previous chapter. The new chapters are automatically added to your account, so you can also check back there any time you're ready and download or read them online.

I am a Packt subscriber, do I get Early Access? Chevron down icon Chevron up icon

Yes, all Early Access content is fully available through your subscription. You will need to have a paid for or active trial subscription in order to access all titles.

How is Early Access delivered? Chevron down icon Chevron up icon

Early Access is currently only available as a PDF or through our online reader. As we make changes or add new chapters, the files in your Packt account will be updated so you can download them again or view them online immediately.

How do I buy Early Access content? Chevron down icon Chevron up icon

Early Access is a way of us getting our content to you quicker, but the method of buying the Early Access course is still the same. Just find the course you want to buy, go through the check-out steps, and you’ll get a confirmation email from us with information and a link to the relevant Early Access courses.

What is Early Access? Chevron down icon Chevron up icon

Keeping up to date with the latest technology is difficult; new versions, new frameworks, new techniques. This feature gives you a head-start to our content, as it's being created. With Early Access you'll receive each chapter as it's written, and get regular updates throughout the product's development, as well as the final course as soon as it's ready.We created Early Access as a means of giving you the information you need, as soon as it's available. As we go through the process of developing a course, 99% of it can be ready but we can't publish until that last 1% falls in to place. Early Access helps to unlock the potential of our content early, to help you start your learning when you need it most. You not only get access to every chapter as it's delivered, edited, and updated, but you'll also get the finalized, DRM-free product to download in any format you want when it's published. As a member of Packt, you'll also be eligible for our exclusive offers, including a free course every day, and discounts on new and popular titles.