augmented reality bt3naaa(2)

8/6/2019 Augmented Reality Bt3naaa(2)

1/15


2/15

Introduction

Augmented reality (AR) is a term for alive direct or indirect view of a physicalreal-world environment whose elements

are augmentedby virtual computer-generated imagery.

It is a combination of the real sceneviewed by the user and a virtual scene

generated by the computer thataugments the scene with additionalinformation.


3/15

GOAL The ultimate goal is to create a system

such that the user can not tell the

difference between the real world and

the virtual augmentation of it.To theuser of this ultimate system it would

appear that he is looking at a single real

scene.


4/15

Augmented Reality vs. Virtual

Reality The phrase was originated by Jaron Lanier the founderof VPL Research one of the original companies sellingvirtual reality systems.

There are three key points in this definition.1. this virtual environment is a computer generatedthree-dimensional scene which requires highperformance computer graphics to provide anadequate level of realism.

2. The second point is that the virtual world is interactive.

A user requires real-time response from the system tobe able to interact with it in an effective manner.

3. The last point is that the user is immersed in thisvirtual environment.


5/15

The user is completely immersed in an artificial world

and becomes divorced from the real environment.

For this immersion to appear realistic the virtual reality

system must accurately sense how the user is moving

and determine what effect that will have on the scene

being rendered in the head mounted display.

The virtual images are merged with the real view to

create the augmented display


6/15

The computer generated virtual objects must be

accurately registered with the real world in all

dimensions. Errors in this registration will prevent the

user from seeing the real and virtual images as

fused. The correct registration must also be

maintained while the user moves about within the

real environment


7/15

Milgram

describes a taxonomy that identifies how

augmented reality and virtual reality

work are related


8/15

The real world and a totally virtual environment

are at the two ends of this continuum with themiddle region called Mixed Reality.

Augmented reality lies near the real world end of

the line with the predominate perception being the

real world augmented by computer generateddata.

Augmented virtuality is a term created by Milgram

to identify systems which are mostly synthetic with

some real world imagery added such as texturemapping video onto virtual objects. This is a

distinction that will fade as the technology

improves and the virtual elements in the scene

become less distinguishable from the real ones.


9/15

Augmented Reality

Application Domains

EntertainmentMovie special effects make use of digital compositing

to create illusions . Strictly speaking with current

technology this may not be considered augmented

reality because it is not generated in real-time. Mostspecial effects are created off-line, frame by frame

with a substantial amount of user interaction and

computer graphics system rendering. But some work

is progressing in computer analysis of the live action

images to determine the camera parameters and usethis to drive the generation of the virtual graphics

objects to be merged.


10/15

An Augmented Reality System Typical Augmented Reality System

A standard virtual reality system seeks to completelyimmerse the user in a computer generatedenvironment. This environment is maintained by thesystem in a frame of reference registered with thecomputer graphic system that creates the renderingof the virtual world. For this immersion to be effective,the egocentered frame of reference maintained bythe user's body and brain must be registered with the

virtual world reference. This requires that motions orchanges made by the user will result in theappropriate changes in the perceived virtual world.


11/15


12/15

The scene is viewed by an imaging device, which in thiscase is depicted as a video camera. The camera performsa perspective projection of the 3D world onto a 2D imageplane. The intrinsic (focal length and lens distortion) andextrinsic (position and pose) parameters of the device

determine exactly what is projected onto its image plane.The generation of the virtual image is done with astandard computer graphics system. The virtual objectsare modeled in an object reference frame. The graphicssystem requires information about the imaging of the realscene so that it can correctly render these objects. Thisdata will control the synthetic camera that is used to

generate the image of the virtual objects. This image isthen merged with the image of the real scene to form theaugmented reality image.


13/15

Augmented reality software

ARToolKit is a software library for building AugmentedReality (AR) applications. These are applications thatinvolve the overlay of virtual imagery on the real world.For example, in the image to the right a three-dimensionalvirtual character appears standing on a real card. It canbe seen by the user in the head set display they arewearing. When the user moves the card, the virtualcharacter moves with it and appears attached to the realobject.

One of the key difficulties in developing Augmented

Reality applications is the problem of tracking the usersviewpoint. In order to know from what viewpoint to drawthe virtual imagery, the application needs to know wherethe user is looking in the real world.


14/15

ARToolKit uses computer vision algorithms

to solve this problem. The ARToolKit video tracking

libraries calculate the real camera position and

orientation relative to physical markers in real time.

This enables the easy development of a wide

range of Augmented Reality applications.

Some of the features of ARToolKit include:


15/15

Single camera position/orientation tracking.

Tracking code that uses simple blacksquares.

The ability to use any square markerpatterns.

Easy camera calibration code.

Fast enough for real time AR applications.

SGIIRIX, Linux, MacOS and Windows OSdistributions.

Distributed with complete source code.

augmented reality bt3naaa(2)

Documents