AUGMENTED REALITY. Antonino Furnari

Transcription

1 IPLab - Image Processing Laboratory Dipartimento di Matematica e Informatica Università degli Studi di Catania AUGMENTED REALITY Antonino Furnari furnari@dmi.unict.it Computer Vision A.Y

2 AUGMENTED REALITY a live copy, view of a physical, real-world environment whose elements are augmented (or supplemented) by computer-generated sensory input such as sound, video, graphics or GPS data it is related to a more general concept called mediated reality, in which a view of reality is modified (possibly even diminished rather than augmented) by a computer as a result, the technology functions by enhancing one s current perception of reality. wikipedia

3 APPLICATIONS

4 VISION BASED AUGMENTED REALITY Computer Vision allows to create augmented reality applications by superimposing 2D or 3D contents on the scene; In order to do so we need to: 1) detect and track the area where to show the content; 2) estimate its 3D position in the real world; 3) render the 2D/3D content according to the estimated position and the inferred geometry of the scene; Two main technologies: fiduciary markers; markerless (i.e., object detection).

5 SOME HISTORY The term augmented reality appears since the 1940s; The first augmented head mounted display is invented by Ivan Sutherland in 1968; First systems using mobile devices, internet and geolocalization appear in the 90s; Advances in the 2000s; Augmented Reality diffusion in the 2010s.

6 HARDWARE Some technologies which make AR interesting: Handheld: Mobile phones; Tablets; Wearable devices: Google glass; Microsoft Holo Lens; Orcam (video - Epson Moverio.

7 FIDUCIARY MARKERS AUGMENTED REALITY: ARTOOLKIT ARToolkit is an Open Source toolkit for marker-based augmented reality; It is quite old (last update in 2007) but still a good starting point for understanding the AR concepts (open & well documented); It offers functions for detecting and tracking single or multiple markers while relaying on OpenGL/glut for 2D/3D rendering;

8 ARTOOLKIT DEMO

9 ARTOOLKIT For additional informations about the next topics, the reader is referred to the very well written ARToolkit documentation and tutorials: Some other useful information can be found in the examples provided with the toolkit;

10 BASIC PRINCIPLES

11 FIDUCIARY MARKERS The marker plays the role of an object which geometry is known; In particular: we chose markers which are easily detectable (thick black borders); we know the real world size of the marker; we chose the inner symbol which is neither horizontally nor vertically symmetric in order to estimate its rotation.

12 MARKER DETECTION original image thresholded image connected components contours edges and corners fitted square

13 MARKER DETECTION A simple detection algorithm is used to find just candidates: any pattern with thick black borders; The actual marker is found normalizing the candidates and comparing them with the searched pattern using template matching; The candidate giving the highest confidence is selected.

14 MARKER MATCHING found candidates... normalized candidates searched pattern......

15 ESTIMATION OF THE 3D POSITION AND ORIENTATION Now that we have an object which geometry, size, position and orientation are known, we can estimate its 3D position with respect to the camera; It can be done computing the extrinsic parameters as seen for camera calibration; Intrinsic parameters which are good for most cameras are part of the toolkit. Specific parameters can be obtained calibrating the camera.

16 ARTOOLKIT COORDINATE SYSTEMS

17 EXVIEW DEMO

18 ARTOOLKIT CAMERA CALIBRATION Intrinsic parameters which are enough general to work with most of the cameras are available in the toolkit; However, in order to improve the detection and tracking performances, a utility for camera calibration is provided in order to calibrate your own camera.

19 MARKERLESS AUGMENTED REALITY? Tracking a number of feature points (e.g., SIFT) in order to detect a marker object (e.g., a photo) and to estimate its position and orientation.

20 AUGMENTED REALITY TOOLKITS

21 DEMO TIME

22 QUESTION TIME

23 CONTACTS For any doubts feel free to contact me: Room 30; Slides availabe at: My personal page: Studium course page