Book Image

OpenNI Cookbook

By : Soroush Falahati
Book Image

OpenNI Cookbook

By: Soroush Falahati

Overview of this book

The release of Microsoft Kinect, then PrimeSense Sensor, and Asus Xtion opened new doors for developers to interact with users, re-design their application’s UI, and make them environment (context) aware. For this purpose, developers need a good framework which provides a complete application programming interface (API), and OpenNI is the first choice in this field. This book introduces the new version of OpenNI. "OpenNI Cookbook" will show you how to start developing a Natural Interaction UI for your applications or games with high level APIs and at the same time access RAW data from different sensors of different hardware supported by OpenNI using low level APIs. It also deals with expanding OpenNI by writing new modules and expanding applications using different OpenNI compatible middleware, including NITE. "OpenNI Cookbook" favors practical examples over plain theory, giving you a more hands-on experience to help you learn. OpenNI Cookbook starts with information about installing devices and retrieving RAW data from them, and then shows how to use this data in applications. You will learn how to access a device or how to read data from it and show them using OpenGL, or use middleware (especially NITE) to track and recognize users, hands, and guess the skeleton of a person in front of a device, all through examples.You also learn about more advanced aspects such as how to write a simple module or middleware for OpenNI itself. "OpenNI Cookbook" shows you how to start and experiment with both NIUI designs and OpenNI itself using examples.

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OpenNI Cookbook
Soroush Falahati
Jul, 2013 | 324 pages
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Table of Contents (14 chapters)
OpenNI Cookbook
OpenNI Cookbook
Credits
Credits
About the Author
About the Author
About the Reviewers
About the Reviewers
www.PacktPub.com
www.PacktPub.com
Preface
Preface
Free Chapter
1
Getting Started
Getting Started
Introduction
Downloading and installing OpenNI
Downloading and installing NiTE
Downloading and installing the Microsoft Kinect SDK
Connecting Asus Xtion and PrimeSense sensors
Connecting Microsoft Kinect
2
OpenNI and C++
OpenNI and C++
Introduction
Creating a project in Visual Studio 2010
OpenNI class and error handling
Enumerating a list of connected devices
Accessing video streams (depth/IR/RGB) and configuring them
Retrieving a list of supported video modes for depth stream
Selecting a specific device for accessing depth stream
Listening to the device connect and disconnect events
Opening an already recorded file (ONI file) instead of a device
3
Using Low-level Data
Using Low-level Data
Introduction
Configuring Visual Studio 2010 to use OpenGL
Initializing and preparing OpenGL
Reading and showing a frame from the image sensor (color/IR)
Reading and showing a frame from the depth sensor
Controlling the player when opening a device from file
Recording streams to file (ONI file)
Event-based reading of data
4
More about Low-level Outputs
More about Low-level Outputs
Introduction
Cropping and mirroring frames right from the buffer
Syncing image and depth sensors to read new frames from both streams at the same time
Overlaying the depth frame over the image frame
Converting the depth unit to millimetre
Retrieving the color of the nearest point without depth over color registration
Enabling/disabling auto exposure and auto white balance
5
NiTE and User Tracking
NiTE and User Tracking
Introduction
Getting a list of all the active users
Identifying and coloring users' pixels in depth map
Reading users' bounding boxes and center of mass
Event-based reading of users' data
6
NiTE and Hand Tracking
NiTE and Hand Tracking
Introduction
Recognizing predefined hand gestures
Tracking hands
Finding the related user ID for each hand ID
Event-based reading of hands' data
Working sample for controlling the mouse by hand
7
NiTE and Skeleton Tracking
NiTE and Skeleton Tracking
Introduction
Detecting a user's pose
Getting a user's skeleton joints and displaying their position in the depth map
Designing a simple pong game using skeleton tracking
Index
Index

Reading users' bounding boxes and center of mass

In this recipe, we are going to expand on the preceding recipe by showing the bounding box and the center of visual mass (COM) of a user. The bounding box of a user shows the size and location of a user in screen and, for any user, the center of the visual mass is the center of distribution of the pixels.

More precisely, its x position is equal to the average of all the users' pixels x position, and its y position is equal to the average of all the users' pixels y position.

Almost the same is true about its z position, which is equal to the average of all the depth values of users' pixels.

Getting ready

Create a project in Visual Studio and prepare it for working with OpenNI and NiTE using the Create a project in Visual Studio 2010 recipe in Chapter 2, OpenNI and C++, and then configure Visual Studio to use OpenGL using the Configuring Visual Studio 2010 to use OpenGL recipe in the previous chapter.

Then copy the code from the Identifying and coloring...

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