ARTag -last updated Feb/2009

Check out Columbia University's Goblin XNA project where you can create ARTag applications for Windows and the Xbox.

See ARTag videos on Youtube (type in "ARTag" as a search term).

Learn to program with ARTag and OpenGL with the book Augmented Reality: A Practical Guide .

Welcome to ARTag! ARTag is an "Augmented Reality" system where virtual objects, games, and animations appear to enter the real world. 3D graphics is added in real time to video, similar to "view matching" in Hollywood, except that with Augmented Reality it is happening online. ARTag "Magic Lens" and "Magic Mirror" systems use arrays of the square ARTag markers added to objects or the environment allowing a computer vision algorithm to calculate the camera "pose" in real time, allowing the CG (computer graphics) virtual camera to be aligned. This gives the illusion of 3D animations or video games to appear to belong in the real world.

ARTag "Magic Lens" systems:

See demo "Magic Lens" videos on video page

ARTag "Magic Mirror" systems:

See demo "Magic Mirror" video on video page

Augmented Reality

What is "Augmented Reality"? Augmented Reality is virtual reality added to real imagery, imagine a camcorder where as you look through the viewfinder, you see some computer generated 3D objects drawn on top of the video picture. For example virtual chess pieces could be drawn on top of an empty chess board. The computer must know where the camcorder is relative to the chess board in order to know how to "augment" the image correctly. One way to achieve this is to put marker patterns in the scene, when this marker is recognized in the camera image, the computer rendering the virtual chess pieces knows what position and angle to render them and draw them over the camera image so that it appears natural to you looking through the viewfinder.

A more concise definition is: Augmented Reality (AR), also known as "Mixed Reality" is where virtual and real objects appear together in a real time system. A prominent meeting place and showcase for AR technology is the annual international conference ISMAR .

AR requires aligning a virtual camera with the real one, and overlaying or combining the imagery for both, to be displayed on some computer monitor, hand-held or wearable display. Tracking the real camera pose is a fundamental part of AR. The system can be simplified if computer vision is used to find the camera pose, instead of some expensive specialized external sensors (acoustic, LED, RF, magnetic). AR is increasing becoming a field where computer vision and graphics meet. artoolkit is a system invented by Hirokazu Kato that uses computer vision and markers to achieve AR using just a video or webcam. ARToolkit was created several years ago and achieves good functionality with limited processor power, ARToolkit has been used and is still used by many graduate students. ARTag was inspired by ARToolkit, but came out later in Nov 2004 taking advantage of the increased computing processing power available. ARTag uses more complex image processing and digital symbol processing to achieve a higher reliability and immunity to lighting (see comparisons ).

There are two ways to use ARTag AR; "Magic Lens" and "Magic Mirror". With a "Magic Lens", a user holds a tablet PC, PDA, or camera cell phone (or any computer device with a dispay and camera) and looks "through" it to see the mixture of real and virtual reality. A Magic Lens system is mostly a private experience, every user needs their own hardware, whereas in a "Magic Mirror" system a single video camera looks out from near a large screen and users see their "reflection" with 3D content added.

AR with the "Magic Lens" metaphor brings 3D computer data into the real world instead of forcing humans to go into the computer world, moving a camera, object, or tablet PC/PDA around is more intuitive than learning key and mouse actions to move around a virtual environemnt.

Demo Download

To try out AR with ARTag, download the Windows demos below. Print out the patterns and use your webcam to see AR work on your computer!
Click The Banner Below to Download.

ARTag Rev2 demo instructions: below are the steps to try it quickly:

1 -Install a USB webcam or frame grabber on your PC, run the program that comes with the camera or frame grabber to make sure it works and you see a picture.

2 -Print out the three pattern files from the patterns\ directory, print base0.gif and toolbar0_7.gif to each fill an 8.5x11" (or A4) page, and print pointer1.gif to be 4" (10.2cm) wide. They should look like this:

3 -Try the different programs in the directories. Basic_artag_opengl works with base0.gif and demonstrates the OpenGL rendering relative to an ARTag marker array. 2d_augmentations uses toolbar0_7.gif showing simple 2D overlays (with optional rotation and alpha blending), and 3d_augmentations uses toolbar0_7.gif and base0.gif and renders 3D objects (projectively distorted but will still work if camera focal length is not set correctly in setup_artag_3d.cfg. Artag_cad uses base0.gif and pointer1.gif.

Below are screen shots of the demo programs you can download (the images are with extra 3D content that we could not put in the download for copyright reasons). You can modify the .cfg configuration files and put in your own 3D models and 2D overlays.

3D Augmentations - 3D objects loaded from WRL (VRML), OBJ (Wavefront, Maya), ASE (3D-Studio export)

2D Augmentations and "ARTag CAD" - left image = 2D augmentations with alpha channels, right images = "ARTag CAD" demonstrating transferring points from one 3D object to another

ARTag Rev2 is a complete AR system which includes marker arrays and the computer vision to find them in images, OpenGL support, and an SDK that you can use to make your own programs (below).

Get ARTag Rev2 SDK

If you wish to add ARTag to your programs, you (could in the past) download the packages for Windows, Linux, and Mac OSX (PPC and x86).

ARTag has been taken down from the NRC download site (not active below) since the principal investigator's (myself Mark Fiala) contract has expired and is no longer an NRC employee. Augmented reality and computer vision research has been halted by NRC management. I am attempting to procure a license and continue providing ARTag, success seems uncertain. Please check back later.

Commercial ARTag Licenses

Please check back later for commercial products and licensing.

More about the Magic Mirror

Below left shows a Magic Mirror setup with the projection screen "mirror" and the digital video camera. A set of hand-held and wearable objects are created mounted with ARTag markers. The right images show what the camera sees, the markers that are detected, the coordinate frames belonging to different objects defined, and used to augment 3D content.

More about how ARTag works

To learn more about how the fiducial marker system of ARTag works, read the next page on ARTag Rev1: marker Detection
or read the publications newer , or older .