This paper describes an enhancement method for location tracking system based on Received Signal Strength Indicator (RSSI)values and Extended Kalman Filter (EKF). The enhancement is based on pre calibration of measurement vectors and individual position block usage in final estimation of the target's position. The EKF and the described enhancement methods are used on a standard Wireless Local A...

Freehand three-dimensional ultrasound is a technique for acquiring ultrasonic data of a 3D volume by recording the trajectory of the ultrasound probe using a position sensor. In planning and registration, a freehand ultrasound systems is used to track a two-dimensional probe. Probe calibration is necessary to find the rigid body transformation from the coordinate system of the B-scan to that of...

In this paper an eeective technique of camera calibration based on a 3D-point-grid is presented. The properties of structured space points, deened as 3D-point-grid, and their relations under perspective transformation are analyzed. Upon the correspondence between these 3D-points and their image points a calibration is made not only to compute the parameters of camera model by a linear method si...

We present a novel technique for calibrating a zooming camera based on the invariance properties of the Normalised Image of the Absolute Conic (NIAC). We show that the camera parameters independent of position, orientation and zooming are determined uniquely by the NIAC, and we exploit these invariance properties to develop a stratified calibration method that decouples the calibration paramete...

This paper introduces a novel method for ultrasound (US) probe calibration based on closed-form formulation and using minimal US imaging allowing for an immediate result. Prior to calibration, a position sensor is used to track each image in 3D space while the US image is used to determine target location within the image. The calibration procedure uses these two pieces of information to determ...

A new approach to camera calibration by vanishing lines is proposed. Calibrated parameters include the orientation, the position, and the focal length of a camera. A hexagon is employed as the calibration target to generate a vanishing line of the ground plane from its projected image. It is shown that the vanishing line includes useful geometric hints about the camera orientation parameters an...

By Gareth Douglas Cole, M.S. Washington State University May 2007 Chair: Sankar Jayaram Electromagnetic tracking systems used in virtual reality applications are subject to tracking error due to magnetic field distortions caused by metallic objects in the environment which increases with increased distance from the transmitter. These problems can lead to a significant decrease in tracking perfo...

PURPOSE: Augmented reality systems have been proposed for image-guided needle interventions but they have not become widely used in clinical practice due to restrictions such as limited portability, low display refresh rates, and tedious calibration procedures. We propose a handheld tablet-based self-calibrating image overlay system. METHODS: A modular handheld augmented reality viewbox was con...

This paper addresses the problem of calibrating a camera mounted on a robot arm. The objective is to estimate the camera's intrinsic and extrinsic parameters. These include the relative position and orientation of camera with respect to robot base as well as the relative position and orientation of the camera with respect to a pre-defined world frame. A calibration object with a known 3D shape ...

We present a technique for 3D ultrasound probe calibration which does not require measurements from the position sensor. The principle of operation is that the beam is aligned with a set of coplanar wires strung across a rigid frame. The probe and frame are mounted on a precision-manufactured mechanical instrument which allows adjustment and measurement of their relative pose. Semi-automatic im...