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143
An Introduction to the Kalman Filter
- UNIVERSITY OF NORTH CAROLINA AT CHAPEL HILL
, 1995
"... In 1960, R.E. Kalman published his famous paper describing a recursive solution to the discrete-data linear filtering problem. Since that time, due in large part to advances in digital computing, the Kalman filter has been the subject of extensive research and application, particularly in the area o ..."
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Cited by 1146 (13 self)
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In 1960, R.E. Kalman published his famous paper describing a recursive solution to the discrete-data linear filtering problem. Since that time, due in large part to advances in digital computing, the Kalman filter has been the subject of extensive research and application, particularly in the area of autonomous or assisted navigation.
The Kalman filter is a set of mathematical equations that provides an efficient computational (recursive) means to estimate the state of a process, in a way that minimizes the mean of the squared error. The filter is very powerful in several aspects: it supports estimations of past, present, and even future states, and it can do so even when the precise nature of the modeled system is unknown.
The purpose of this paper is to provide a practical introduction to the discrete Kalman filter. This introduction includes a description and some discussion of the basic discrete Kalman filter, a derivation, description and some discussion of the extended Kalman filter, and a relatively simple (tangible) example with real numbers & results.
Marker tracking and HMD calibration for a video-based augmented reality conferencing system
- in The 2nd International Workshop on Augmented Reality (IWAR 99
, 1999
"... We describe an augmented reality conferencing system which uses the overlay of virtual images on the real world. Remote collaborators are represented on Virtual Monitors which can be freely positioned about a user in space. Users can collaboratively view and interact with virtual objects using a sha ..."
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Cited by 527 (26 self)
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We describe an augmented reality conferencing system which uses the overlay of virtual images on the real world. Remote collaborators are represented on Virtual Monitors which can be freely positioned about a user in space. Users can collaboratively view and interact with virtual objects using a shared virtual whiteboard. This is possible through precise virtual image registration using fast and accurate computer vision techniques and HMD calibration. We propose a method for tracking fiducial markers and a calibration method for optical see-through HMD based on the marker tracking. 1.
A Touring Machine: Prototyping 3D Mobile Augmented Reality Systems for Exploring the Urban Environment
, 1997
"... We describe a prototype system that combines together the overlaid 3D graphics of augmented reality with the untethered freedom of mobile computing. The goal is to explore how these two technologies might together make possible wearable computer systems that can support users in their everyday inter ..."
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Cited by 373 (36 self)
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We describe a prototype system that combines together the overlaid 3D graphics of augmented reality with the untethered freedom of mobile computing. The goal is to explore how these two technologies might together make possible wearable computer systems that can support users in their everyday interactions with the world. We introduce an application that presents information about our university’s campus, using a head-tracked, see-through, headworn, 3D display, and an untracked, opaque, handheld, 2D display with stylus and trackpad. We provide an illustrated explanation of how our prototype is used, and describe our rationale behind designing its software infrastructure and selecting the hardware on which it runs.
SCAAT: Incremental Tracking with Incomplete Information
, 1997
"... We present a promising new mathematical method for tracking a user's pose (position and orientation) for interactive computer graphics. The method, which is applicable to a wide variety of both commercial and experimental systems, improves accuracy by properly assimilating sequential observatio ..."
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Cited by 160 (14 self)
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We present a promising new mathematical method for tracking a user's pose (position and orientation) for interactive computer graphics. The method, which is applicable to a wide variety of both commercial and experimental systems, improves accuracy by properly assimilating sequential observations, filtering sensor measurements, and by concurrently autocalibrating source and sensor devices. It facilitates user motion prediction, multisensor data fusion, and higher report rates with lower latency than previous methods. Tracking systems determine the user's pose by measuring signals from low-level hardware sensors. For reasons of physics and economics, most systems make multiple sequential measurements which are then combined to produce a single tracker report. For example, commercial magnetic trackers using the SPASYN ( Space Synchro) system sequentially measure three magnetic vectors and then combine them mathematically to produce a report of the sensor pose. Our new approach produces tracker reports as each new lowlevel sensor measurement is made rather than waiting to form a complete collection of observations. Because single observations under-constrain the mathematical solution, we refer to our approach as single-constraint-at-a-time or SCAAT tracking. The key is that the single observations provide some information about the user's state, and thus can be used to incrementally improve a previous estimate. We recursively apply this principle, incorporating new sensor data as soon as it is measured. With this approach we are able to generate estimates more frequently, with less latency, and with improved accuracy. We present results from both an actual implementation, and from extensive simulations.
Fast and Globally Convergent Pose Estimation From Video Images
, 1998
"... Determining the rigid transformation relating 2D images to known 3D geometry is a classical problem in photogrammetry and computer vision. Heretofore, the best methods for solving the problem have relied on iterative optimization methods which cannot be proven to converge and/or which do not effecti ..."
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Cited by 151 (6 self)
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Determining the rigid transformation relating 2D images to known 3D geometry is a classical problem in photogrammetry and computer vision. Heretofore, the best methods for solving the problem have relied on iterative optimization methods which cannot be proven to converge and/or which do not effectively account for the orthonormal structure of rotation matrices. We show that the pose estimation problem can be formulated as that of minimizing an error metric based on collinearity in object (as opposed to image) space. Using object space collinearity error, we derive an iterative algorithm which directly computes orthogonal rotation matrices and which is globally convergent. Experimentally, we show that the method is computationally efficient, that it is no less accurate than the best currently employed optimization methods, and that it outperforms all tested methods in robustness to outliers. Chien-Ping Lu, Silicon Graphics Inc. cplu@engr.sgi.com y Greg Hager, Department of Computer...
Calibration-free augmented reality
- IEEE Transactions on Visualization and Computer Graphics
, 1998
"... Abstract—Camera calibration and the acquisition of Euclidean 3D measurements have so far been considered necessary requirements for overlaying three-dimensional graphical objects with live video. In this article, we describe a new approach to videobased augmented reality that avoids both requirement ..."
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Cited by 106 (0 self)
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Abstract—Camera calibration and the acquisition of Euclidean 3D measurements have so far been considered necessary requirements for overlaying three-dimensional graphical objects with live video. In this article, we describe a new approach to videobased augmented reality that avoids both requirements: It does not use any metric information about the calibration parameters of the camera or the 3D locations and dimensions of the environment’s objects. The only requirement is the ability to track across frames at least four fiducial points that are specified by the user during system initialization and whose world coordinates are unknown. Our approach is based on the following observation: Given a set of four or more noncoplanar 3D points, the projection of all points in the set can be computed as a linear combination of the projections of just four of the points. We exploit this observation by 1) tracking regions and color fiducial points at frame rate, and 2) representing virtual objects in a non-Euclidean, affine frame of reference that allows their projection to be computed as a linear combination of the projection of the fiducial points. Experimental results on two augmented reality systems, one monitor-based and one head-mounted, demonstrate that the approach is readily implementable, imposes minimal computational and hardware requirements, and generates real-time and accurate video overlays even when the camera parameters vary dynamically. Index Terms—Augmented reality, real-time computer vision, calibration, registration, affine representations, feature tracking, 3D interaction techniques.
ARQuake: An Outdoor/Indoor Augmented Reality First Person Application
- In 4th Int'l Symposium on Wearable Computers
, 2000
"... This pap er presents an outdoor/indoor augmented re- ality first person applic ationAR(2uake we have developal. ARQuake is an extension of the desktop game Quake, and as such we are investigating how to convert a desktop first person application into an outdoor/indoor mobile augmented reality applic ..."
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Cited by 95 (13 self)
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This pap er presents an outdoor/indoor augmented re- ality first person applic ationAR(2uake we have developal. ARQuake is an extension of the desktop game Quake, and as such we are investigating how to convert a desktop first person application into an outdoor/indoor mobile augmented reality application. We present an archire cture for a low cost, moderately accurate six degrees of freedom tracking system based on GP$, digital compass, and fiducial vision-based tracking. Usability issues such as monster selection, colour, and input devies are discussed. A second application for AR architectural design visualisation is presented.
Hybrid inertial and vision tracking for augmented reality registration
- In Proceedings of Virtual Reality
, 1999
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Matrix: A Realtime Object Identification and Registration Method for Augmented Reality
, 1998
"... This paper introduces a new technique for producing augmented reality systems that simultaneously identify real world objects and estimate their coordinate systems. This method utilizes a 2D matrix marker, a square shaped barcode, which can identify a large number of objects. It also acts as a landm ..."
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Cited by 69 (2 self)
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This paper introduces a new technique for producing augmented reality systems that simultaneously identify real world objects and estimate their coordinate systems. This method utilizes a 2D matrix marker, a square shaped barcode, which can identify a large number of objects. It also acts as a landmark to register information on real world images. As a result, it costs virtually nothing to produce and attach codes on various kinds of real world objects, because the matrix code are printable. We have developed an augmented reality system based on this method, and demonstrated several potential applications.
