Computer-aided Tracking Research Articles

CAT & MAUS: A novel system for true dynamic motion measurement of underlying bony structures with compensation for soft tissue movement.

Optoelectronic motion capture systems are widely employed to measure the movement of human joints. However, there can be a significant discrepancy between the data obtained by a motion capture system (MCS) and the actual movement of underlying bony structures, which is attributed to soft tissue artefact. In this paper, a computer-aided tracking and motion analysis with ultrasound (CAT & MAUS) system with an augmented globally optimal registration algorithm is presented to dynamically track the underlying bony structure during movement. The augmented registration part of CAT & MAUS was validated with a high system accuracy of 80%. The Euclidean distance between the marker-based bony landmark and the bony landmark tracked by CAT & MAUS was calculated to quantify the measurement error of an MCS caused by soft tissue artefact during movement. The average Euclidean distance between the target bony landmark measured by each of the CAT & MAUS system and the MCS alone varied from 8.32mm to 16.87mm in gait. This indicates the discrepancy between the MCS measured bony landmark and the actual underlying bony landmark. Moreover, Procrustes analysis was applied to demonstrate that CAT & MAUS reduces the deformation of the body segment shape modeled by markers during motion. The augmented CAT & MAUS system shows its potential to dynamically detect and locate actual underlying bony landmarks, which reduces the MCS measurement error caused by soft tissue artefact during movement.

A computer-aided tracking and motion analysis with ultrasound (CAT & MAUS) system for the description of hip joint kinematics.

Investigation of joint kinematics contributes to developing a better understanding of musculoskeletal conditions. However, the most commonly used optoelectronic motion analysis systems cannot determine the movements of underlying bone landmarks with high accuracy because of soft tissue artefacts. The aim of this paper was to present a computer-aided measurement system to track the underlying bone anatomy in a 3D global coordinate frame and describe hip joint kinematics of ten healthy volunteers during gait. We have developed a measurement tool with an image-based computer-aided post-processing pipeline for automatic bone segmentation in ultrasound (US) images and a globally optimal 3D surface-to-surface registration method to quantify hip joint movements. The segmentation algorithm exploits US intensity profiles, including information about the integrated backscattering, acoustic shadows, and local phase features. A global optimization method is applied based on the traditional iterative closest point registration algorithm, which is robust to initialization. The International Society of Biomechanics recommended joint kinematics descriptor has been adapted to calculate the joint kinematics. The developed system prototype has been validated with a ball-joint femoral phantom and tested in vivo with 10 volunteers. The maximum Euclidean distance error of the automatic bone segmentation is less than 2 pixels (approximately 0.2mm). The maximum absolute rotation angle error is less than [Formula: see text]. This computer-aided tracking and motion analysis with ultrasound (CAT & MAUS) system shows the feasibility of describing hip joint kinematics for clinical investigation and diagnosis using an image-based solution.

Globally Optimal Registration for Describing Joint Kinematics

Investigation of joint kinematics contributes to a better understanding of musculoskeletal condition pathologies. However, the most commonly used optoelectronic motion analysis systems cannot determine the movements of underlying bone landmarks with high accuracy because of soft tissue artifact. We are developing a computer-aided tracking and motion analysis with ultrasound (CAT & MAUS) system to track the underlying bone anatomy in a 3D global coordinate frame for describing joint kinematics. To quantify the rotation and translation of joints, registration is an essential component in our computer-aided tracking pipeline. In this paper, we consider a globally optimal Iterative Closest Point (ICP) registration algorithm to quantify joint kinematics. We use a global branch-and-bound (BnB) scheme to speed up the search in the entire 3D motion space. A globally optimal result is guaranteed by iterating the BnB scheme and ICP registration. We collected phantom data for validation and in-vivo data from ten healthy volunteers. The globally optimal ICP registration results have been compared to the results from traditional ICP registration. The overall average rotation angle error is less than 1̊. The registration result is then converted into local joint coordinate systems defined by the International Society of Biomechanics for joint kinematics description. The results from globally optimal registration defined a general hip joint kinematics model of healthy subjects during gait which can be compared as a reference to the results from subjects with hip joint conditions.

A novel multitarget tracking algorithm for Myosin VI protein molecules on actin filaments in TIRFM sequences.

We propose a novel multitarget tracking framework for Myosin VI protein molecules in total internal reflection fluorescence microscopy sequences which integrates an extended Hungarian algorithm with an interacting multiple model filter. The extended Hungarian algorithm, which is a linear assignment problem based method, helps to solve measurement assignment and spot association problems commonly encountered when dealing with multiple targets, although a two-motion model interacting multiple model filter increases the tracking accuracy by modelling the nonlinear dynamics of Myosin VI protein molecules on actin filaments. The evaluation of our tracking framework is conducted on both real and synthetic total internal reflection fluorescence microscopy sequences. The results show that the framework achieves higher tracking accuracies compared to the state-of-the-art tracking methods, especially for sequences with high spot density.

Integrating different tracking systems in football: multiple camera semi-automatic system, local position measurement and GPS technologies

During the past decade substantial development of computer-aided tracking technology has occurred. Therefore, we aimed to provide calibration equations to allow the interchangeability of different tracking technologies used in soccer. Eighty-two highly trained soccer players (U14–U17) were monitored during training and one match. Player activity was collected simultaneously with a semi-automatic multiple-camera (Prozone), local position measurement (LPM) technology (Inmotio) and two global positioning systems (GPSports and VX). Data were analysed with respect to three different field dimensions (small, <30 m2 to full-pitch, match). Variables provided by the systems were compared, and calibration equations (linear regression models) between each system were calculated for each field dimension. Most metrics differed between the 4 systems with the magnitude of the differences dependant on both pitch size and the variable of interest. Trivial-to-small between-system differences in total distance were noted. However, high-intensity running distance (>14.4 km · h−1) was slightly-to-moderately greater when tracked with Prozone, and accelerations, small-to-very largely greater with LPM. For most of the equations, the typical error of the estimate was of a moderate magnitude. Interchangeability of the different tracking systems is possible with the provided equations, but care is required given their moderate typical error of the estimate.

Weather-adaptive flying target detection and tracking from infrared video sequences

This paper proposes a new computer-aided tracking method that can track multiple flying targets in an image sequence acquired from either an optical camera or an infrared camera system. The proposed method includes two major steps, which are flying target detection and flying target tracking. Because weather conditions greatly affect the detection of a flying target, we designed a fuzzy system that classifies the weather into two basic weather types. Based on the weather type, flying targets can be detected successfully. In tracking a flying target, we apply the dynamic layer representation method to represent the flying target and use a Kalman filter to predict the target’s position. The second fuzzy rule system is designed to identify the target states, which are visible, missing, or occluded, based on the layer and positional features. Thereafter, the identified state can help to select a suitable tracking strategy for the subsequent frames. In the experiments, we demonstrate the results applied to five real image sequences. The proposed method can successfully detect and track multiple flying targets perfectly in clear weather. It also achieves around 90% accuracy when the weather is not clear. The fuzzy methodology makes the proposed system more effective at detecting and tracking targets and more flexible to complex environmental conditions, since the rules can be easily added and modified.

Homotypic cell-cell contacts stimulate the motile activity of rat prostate cancer cells.

To characterize the effect of homotypic cell-to-cell collisions upon the motile activities of two rat prostatic cancer cell lines of markedly different metastatic potential. The movements of strongly and weakly metastatic MAT-LyLu and AT-2 cells, respectively, were recorded under an inverted microscope at 37 degrees C. The motile activities of the cells at various cell densities were characterized quantitatively by computer-aided tracking methods and image analysis. The following variables were assessed: speed of movement, final displacement, coefficient of movement efficiency, diffusion constant and positive flow. MAT-LyLu and AT-2 cells showed only limited motile activity in sparse cultures where there was little contact amongst the cells. However, under these and all other subsequent conditions tested, the motile activity of the MAT-LyLu cells was higher than the AT-2 cells. As the density of the cultured cells was increased (leading to more cell-to-cell contacts) there was a significant increase in motility. This effect was more pronounced for the AT-2 than for the MAT-LyLu cells, resulting in visible acceleration of movement by direct physical contact among the colliding cells. The motile activities of the tumour cells was only slightly affected by conditioned media. Homotypic collisions between migrating prostatic cancer cells can strongly stimulate their motility. The effect of increased contact is greater on the weakly metastatic cells, such that at high cell density, the difference in the motilities of weak and strong metastatic cells is greatly reduced.

Frameless optical computer-aided tracking of a microscope for otorhinology and skull base surgery.

To integrate a digitally controlled operating microscope without a laser autofocus system into a frameless optical computer-aided surgery system and to test the accuracy and usability of this system in otorhinological surgery. Experimental study and case series. Department of Oto-Rhino-Laryngology, Head and Neck Surgery, Inselspital, and the Maurice E. Müller Institute for Biomechanics, University of Bern, Bern, Switzerland. Eight computer-aided microscopic surgical procedures were performed between January and October 2000 on patients with various diseases of the anterior and lateral skull base. The practical accuracy of the navigated microscope on the lateral side of a cadaver skull was 2.27 +/- 0.25 mm and on the anterior side of the same skull was 2.07 +/- 0.35 mm. In all 8 cases of computer-aided microscopic surgery, no complications occurred. Clinical inaccuracy was 2 to 3 mm. Integration of a low-cost, non-laser autofocus microscope into our computer-aided surgery system was successfully performed and offers surgeons the ability to combine the precise optics of the operating microscope with the localization power of a computer-aided system.

Regulation of switching frequency and bias of the bacterial flagellar motor by CheY and fumarate.

The effect of CheY and fumarate on switching frequency and rotational bias of the bacterial flagellar motor was analyzed by computer-aided tracking of tethered Escherichia coli. Plots of cells overexpressing CheY in a gutted background showed a bell-shaped correlation curve of Switching frequency and bias centering at about 50% clockwise rotation. Gutted cells (i.e., with cheA to cheZ deleted) with a low CheY level but a high cytoplasmic fumarate concentration displayed the same correlation of switching frequency and bias as cells overexpressing CheY at the wild-type fumarate level. Hence, a high fumarate level can phenotypically mimic CheY overexpression by simultaneously changing the switching frequency and the bias. A linear correlation of cytoplasmic fumarate concentration and clockwise rotation bias was found and predicts exclusively counter-clockwise rotation without switching when fumarate is absent. This suggests that (i) fumarate is essential for clockwise rotation in vivo and (ii) any metabolically induced fluctuation of its cytoplasmic concentration will result in a transient change in bias and switching probability. A high fumarate level resulted in a dose-response curve linking bias and cytoplasmic CheY concentration that was offset but with a slope similar to that for a low fumarate level. It is concluded that fumarate and CheY act additively presumably at different reaction steps in the conformational transition of the switch complex from counterclockwise to clockwise motor rotation.

Testing sensomotoric capacity by a computer-aided tracking system

In different brain structures (telencephalon, tectum opticum, rhombencephalon, cerebellum and medulla oblongata) of the teleost Serranus scriba Cuv., the content of glycogen was observed during a 24-h period. A circadian rhythm of brain glycogen concentration was found. The results are discussed with particular reference to the possible relation between catecholamines, cyclic adenine nucleotide and glycogen metabolism in the brain.

An Experimental Study of Image Motion Compensation Tracking for Earth Reconnaissance from Space

An experiment was conducted to investigate man's ability to perform image motion compensation tracking for earth reconnaissance from space. The study investigated: (1) two control system tracking modes—computer-aided tracking and manual tracking, (2) control dynamics—rate and acceleration, (3) controller gain—low, medium, and high, and (4) magnification—1 to 200 power. The two control modes were treated in separate studies based on large performance differences observed during pilot studies. A major objective of the study was to determine the type of control system and the amount of magnification necessary to meet a 0.05 mr/sec image motion compensation tracking performance criterion. The results of the investigation revealed that the manual tracking mode was unacceptable in terms of the system performance criterion; whereas, the computer aided tracking mode yielded performance which met the criterion at several combinations of experimental conditions. Magnification and controller gain levels were found to have highly significant effects on tracking performance. The results are discussed in terms of reconnaissance system design applications.