- Author:
- Richard Lee Holloway
Augmented reality (AR) systems combine three-dimensional computer-generated imagery with the view of the real environment in order to make unseen objects visible or to present additional information. A critical problem is that the computer-generated objects do not currently remain correctly registered with the real environment--objects aligned from one viewpoint appear misaligned from another and appear to swim about as the viewer moves. This registration error is caused by a number of factors, such as system delay, optical distortion, and tracker measurement error, and is difficult to correct with existing technology.
This dissertation presents a registration error model for AR systems and uses it to gain insight into the nature and severity of the registration error caused by the various error sources. My thesis is that a mathematical error model enables the system architect to determine (1) which error sources are the most significant, (2) the sensitivity of the net registration error to each error, (3) the nature of the distortions caused by each type of error, (4) the level of registration accuracy one can expect, and also provides insights on how best to calibrate the system.
Analysis of a surgery planning application yielded the following main results: (1) Even for moderate head velocities, system delay causes more registration error than all other sources combined; (2) Using the eye's center of rotation as the eyepoint in the computer graphics model reduces the error due to eye rotation to zero for points along the line of gaze. This should obviate the need for eye tracking; (3) Tracker error is a significant problem both in head tracking and in system calibration; (4) The World coordinate system should be omitted when possible; (5) Optical distortion is a significant error source, but correcting it computationally in the graphics pipeline often induces delay error larger than the distortion error itself; (6) Knowledge of the nature of the various types of error facilitates identification and correction of errors in the calibration process.
Although the model was developed for see-through head-mounted displays (STHMDs) for surgical planning, many of the results are applicable to other HMD systems as well.
Cited By
- Davis L, Hamza-Lup F and Rolland J A Method for Designing Marker-Based Tracking Probes Proceedings of the 3rd IEEE/ACM International Symposium on Mixed and Augmented Reality, (120-129)
Ikits M, Hansen C and Johnson C A comprehensive calibration and registration procedure for the Visual Haptic Workbench Proceedings of the workshop on Virtual environments 2003, (247-254)- Klein G and Drummond T Robust Visual Tracking for Non-Instrumented Augmented Reality Proceedings of the 2nd IEEE/ACM International Symposium on Mixed and Augmented Reality
- Vlahakis V, Ioannidis N, Karigiannis J, Tsotros M, Gounaris M, Stricker D, Gleue T, Daehne P and Almeida L (2002). Archeoguide, IEEE Computer Graphics and Applications, 22:5, (52-60), Online publication date: 1-Sep-2002.
- Raskar R and Low K Interacting with spatially augmented reality Proceedings of the 1st international conference on Computer graphics, virtual reality and visualisation, (101-108)
- Vlahakis V, Karigiannis J, Tsotros M, Gounaris M, Almeida L, Stricker D, Gleue T, Christou I, Carlucci R and Ioannidis N Archeoguide Proceedings of the 2001 conference on Virtual reality, archeology, and cultural heritage, (131-140)
- Kutulakos K and Vallino J (1998). Calibration-Free Augmented Reality, IEEE Transactions on Visualization and Computer Graphics, 4:1, (1-20), Online publication date: 1-Jan-1998.
- Jacobs M, Livingston M and State A Managing latency in complex augmented reality systems Proceedings of the 1997 symposium on Interactive 3D graphics, (49-ff.)
- Banks D The ImageSwitcher Proceedings of the Eleventh Eurographics conference on Graphics Hardware, (71-77)
- State A, Hirota G, Chen D, Garrett W and Livingston M Superior augmented reality registration by integrating landmark tracking and magnetic tracking Proceedings of the 23rd annual conference on Computer graphics and interactive techniques, (429-438)
Index Terms
- Registration errors in augmented reality systems
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