Innovative geometric pose reconstruction for marker-based single camera tracking.
ABSTRACT Mobile augmented reality applications are in need of tracking systems which can be wearable and do not cause a high processing load, while still offering reasonable performance, robustness and accuracy. The motivation to develop yet another tracking algorithm is two-fold. Most of the existing approaches use classical optimization techniques such as the Gauss-Newton method. However, since those algorithms were developed to address general optimization problems, they do not fully exploit the structure of the pose estimation problem with its geometric constraint targets. Also, mixed reality applications demand that pose estimation be not only accurate but also robust and computationally efficient. Hence there is a need for algorithms that are as accurate as classical algorithms, yet are also globally convergent and fast enough for real-time applications. In this paper we introduce a new iterative geometric method for pose estimation from four co-planar points and we present the current status of PTrack, an infrared marker-based single camera tracking system benefiting from this approach. Our novel pose estimation algorithm identifies possible labels composed of retro-reflective markers in a 2D post-processing using a divide-and-conquer strategy to segment the camera's image space and attempts an iterative geometric D reconstruction of position and orientation in camera space. Tracking results are made available to applications through OpenTracker [OpenTracker 2006] framework. To analyse tracking accuracy and precision, we built a generic test-bed and compared PTrack to ARToolKit [Kato and Billinghurst 1999; Kato et al. 2000], one of the most wide-spread low-cost tracking solutions. Results show that our tracking system achieves competitive accuracy levels better than ARToolKit and close to commercial systems, while being highly stable and affordable.
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Conference Proceeding: Measuring ARTootKit accuracy in long distance tracking experiments[show abstract] [hide abstract]
ABSTRACT: This paper presents the results from an experiment which was performed to test the ARToolKit and the accuracy of its tracking over large distances of 1 to 3 metres. We used ARToolKit to extract the position of a camera pointed at a fiducial marker, and compared these values to physical measurements to quantify the accuracy of the tracking. The results indicate that the error in position increases with the distance from the target, and that the error also varies in X and Y in phase opposition when orbiting around the pattern. We suggest further experiments to perform and the creation of filters which could reduce at least 75% of the errors detected in this initial experiment.Augmented Reality Toolkit, The First IEEE International Workshop; 02/2002
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ABSTRACT: We conduct an exhaustive survey of image thresholding methods, categorize them, express their formulas under a uniform notation, and finally carry their performance comparison. The thresholding methods are categorized according to the information they are exploiting, such as histogram shape, measurement space clustering, entropy, object attributes, spatial correlation, and local gray-level surface. 40 selected thresholding methods from various categories are compared in the context of nondestructive testing applications as well as for document images. The comparison is based on the combined performance measures. We identify the thresholding algorithms that perform uniformly better over nonde- structive testing and document image applications. © 2004 SPIE and IS&T. (DOI: 10.1117/1.1631316)J. Electronic Imaging. 01/2004; 13:146-168.
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ABSTRACT: We present a new tracking system for augmented reality and virtual set applications, based on an inertial navigation system aided by ultrasonic time-of-flight range measurements to a constellation of wireless transponder beacons. An extended Kalman filter operating on 1-D range measurements allows the inertial sensors to filter out corrupt range measurements and perform optimal smoothing and prediction, while at the same time using the pre-screened range measurements to correct the drift of the inertial system. The use of inside-out ultrasonic tracking allows for tetherless tracking over a building-wide range with no acoustic propagation latency. We have created a simulation to account for error sources in the ultrasonic ranging system. The fully implemented tracking system is tested and found to have accuracy consistent with the simulation results. The simulation also predicts that with some further compensation of transducer misalignment, accuracies better than 2 mm can be achieved.01/1998