3D Localization Technique Research Articles

Robust emitter localization with enhanced harmonic analysis.

We present a non-iterative and model-free algorithm for three-dimensional (3D) single emitter localization. Our algorithm decodes the axial position and the emitter width via the ratio of the first and second Fourier harmonic. The retrieved width information is further used for dynamic extraction of the proper region of interest to robustly eliminate the outer noisy background, thus improving the localization precision over existing non-iterative algorithms. Using simulated and experimental datasets, we demonstrate that our algorithm achieves localization precision approaching the state-of-the-art iterative fitting-based methods in all three dimensions at two orders of magnitude faster speed, applicable in various 3D single-molecule localization techniques.

A Survey on DV-Hop localization Techniques in Three- Dimensional Wireless Sensor Networks

Location information is prerequisite for wireless sensor networks (WSNs) monitoring and control applications, since there is no meaning without position information for collected data. Distance vector hop (DV-Hop) localization algorithm as the typical range-free algorithm that has been widely applied in various applications. Nowadays, the research on range-free localization for WSNs is mostly based on two-dimensional (2D) space. Hence, there are few surveys concentrated on range-free localization in three-dimensional (3D) WSNs. This motivated us to present an extensive overview of enhanced DV-Hop localization algorithms in 3D WSNs. This paper focused on critical challenge between 2D and 3D in localization model, representative range-free 3D localization technique surveys. Moreover, a comprehensive taxonomy of most essential enhanced methods applied in 3D DV-Hop is illustrated. A considerable comparison in term of localization error, computational complexity and node type is given. Future research directions dealing with localization under 3D DV-Hop is also discussed.

3D Localization for Internet of Underground Things in Oil and Gas Reservoirs

Magnetic Induction (MI) is an efficient wireless communication method to deploy operational internet of underground things (IoUT) for oil and gas reservoirs. The IoUT consists of underground things which are capable of sensing the underground environment and communicating with the surface. The MI-based IoUT enable many applications, such as monitoring of the oil rigs, optimized fracturing, and optimized extraction. Most of these applications are dependent on the location of the underground things and therefore require accurate localization techniques. The existing localization techniques for MI-based underground sensing networks are two-dimensional and do not characterize the achievable accuracy of the developed methods, which are both crucial and challenging tasks. Therefore, this paper proposes a novel three-dimensional (3D) localization technique based on Isometric scaling (Isomap) for future IoUT. Moreover, this paper also presents the closed-form expression of the Cramer Rao lower bound (CRLB) for the proposed technique, which takes into account the channel parameters of the underground magnetic-induction. The derived CRLB provides the suggestions for an MI-based underground localization system by associating the system parameters with the error trend. Numerical results demonstrate that localization accuracy is affected by different channel and networks parameters such as the number of underground things, ranging error variance, size of the coils, and the transmitting power. The root mean square error performance of the proposed technique shows that increase in the number of turns of the coils, transmitting power, and the number of anchors improves the performance. Results also show that the proposed technique is robust to the ranging error variance in the range of 10 to 30 %; however, a further increase in the ranging error variance does not allow to achieve acceptable accuracy. Also, the results show that the proposed technique achieves an average of 30 % better localization accuracy compare to the traditional methods.

Three-Dimensional Orientation of Anisotropic Plasmonic Aggregates at Intracellular Nuclear Indentation Sites by Integrated Light Sheet Super-Resolution Microscopy.

Three-dimensional (3D) orientations of individual anisotropic plasmonic nanoparticles in aggregates were observed in real time by integrated light sheet super-resolution microscopy ( iLSRM). Asymmetric light scattering of a gold nanorod (AuNR) was used to trigger signals based on the polarizer angle. Controlled photoswitching was achieved by turning the polarizer and obtaining a series of images at different polarization directions. 3D subdiffraction-limited super-resolution images were obtained by superlocalization of scattering signals as a function of the anisotropic optical properties of AuNRs. Varying the polarizer angle allowed resolution of the orientation of individual AuNRs. 3D images of individual nanoparticles were resolved in aggregated regions, resulting in as low as 64 nm axial resolution and 28 nm spatial resolution. The proposed imaging setup and localization approach demonstrates a convenient method for imaging under a noisy environment where the majority of scattering noise comes from cellular components. This integrated 3D iLSRM and localization technique was shown to be reliable and useful in the field of 3D nonfluorescence super-resolution imaging.

A microwave imaging-based 3D localization algorithm for an in-body RF source as in wireless capsule endoscopes.

A microwave imaging-based technique for 3D localization of an in-body RF source is presented. Such a technique can be useful for localization of an RF source as in wireless capsule endoscopes for positioning of any abnormality in the gastrointestinal tract. Microwave imaging is used to determine the dielectric properties (relative permittivity and conductivity) of the tissues that are required for a precise localization. A 2D microwave imaging algorithm is used for determination of the dielectric properties. Calibration method is developed for removing any error due to the used 2D imaging algorithm on the imaging data of a 3D body. The developed method is tested on a simple 3D heterogeneous phantom through finite-difference-time-domain simulations. Additive white Gaussian noise at the signal-to-noise ratio of 30 dB is added to the simulated data to make them more realistic. The developed calibration method improves the imaging and the localization accuracy. Statistics on the localization accuracy are generated by randomly placing the RF source at various positions inside the small intestine of the phantom. The cumulative distribution function of the localization error is plotted. In 90% of the cases, the localization accuracy was found within 1.67 cm, showing the capability of the developed method for 3D localization.

Analysis on Defects Location during Rebar Pull-Out Test by Acoustic Emission Technique

To confirm precision of acoustic emission source localization technique and validate rationality of acoustic emission parameters setting in concrete detection, defects location in pull-out specimens during bond failure were monitored by the method of 3D localization technique. In the monitoring,formation and propagation of cracks calculated by localization algorithm agrees with the real situation. AE parameters proposed in the paper help to identify source location with high accuracy.

Terrain Inclination Aided Three-Dimensional Localization and Mapping for an Outdoor Mobile Robot

A new 3D localization and mapping technique with terrain inclination assistance is proposed in this paper to allow a robot to identify its location and build a global map in an outdoor environment. The Iterative Closest Points (ICP) algorithm and terrain inclination-based localization are combined together to achieve accurate and fast localization and mapping. Inclinations of the terrains the robot navigates are used to achieve local localization during the interval between two laser scans. Using the results of the above localization as the initial condition, the ICP algorithm is then applied to align the overlapped laser scan maps to update the overhanging obstacles for building a global map of the surrounding area. Comprehensive experiments were carried out for the validation of the proposed 3D localization and mapping technique. The experimental results show that the proposed technique could reduce time consumption and improve the accuracy of the performance.

TU-A-213CD-04: A Novel Technique for Estimating and Correcting Cross-Scatter in Dual-Source CBCT

Purpose: Dual-source CBCT may provide several advantages over current on-board 3D localization techniques; however, dual-source CBCT suffers greatly from cross-scatter. A novel technique was developed that includes sampling the cross-scatter only projections (CSPs) during data acquisition and using the CSPs for scatter correction. Methods: Cross-scatter only projections (CSPs) were acquired by firing a single x-ray tube every N degrees. N was determined based on estimating the angular Nyquist frequency of the cross-scatter distribution for three different anatomic sites (head and neck, lung, pelvis) using an anthropomorphic phantom. The Nyquist frequency was estimated by calculating the divergence of angular frequency spectra of rotating phantoms from the noise band created with stationary phantoms. The sampling requirements were empirically verified by varying N and comparing interpolated CSPs with measured CSPs at every projection angle. To correct for cross-scatter, the CSPs were low-pass filtered, then interpolated across projection angle, and then subtracted from the projections. The effects of the correction on contrast and contrast-to-noise ratio (CNR) in reconstructed images were evaluated on an equal-dose basis relative to acquisitions with no cross-scatter present. Results: Approximately the same Nyquist frequency was estimated for all three anatomical sites, 0.035–0.042 cycles per degree, corresponding to somewhat less than 1 sample every 10 degrees. The percent contrast reduction, averaged over several contrast inserts, was 16.4% and 4.5% in the uncorrected and corrected images. CNR was reduced by 19.5% and 13.6%. Conclusions: For the phantom studied, the cross-scatter Nyquist sampling requirement was insensitive to anatomic site. The scatter correction mitigated cross-scatter and CNR degradations relative to cross-scatter-free acquisition, improving both contrast and CNR as compared to uncorrected images reconstructed from cross-scatter-inclusive dual-source acquisition. This project was partially supported by a research grant from Varian Medical Systems

Experimental characterization of 3D localization techniques for particle-tracking and super-resolution microscopy

Three-dimensional (3D) particle localization at the nanometer scale plays a central role in 3D particle tracking and 3D localization-based super-resolution microscopy. Here we introduce a localization algorithm that is independent of theoretical models and therefore generally applicable to a large number of experimental realizations. Applying this algorithm and a convertible experimental setup we compare the performance of the two major 3D techniques based on astigmatic distortions and on multiplane detection. In both methods we obtain experimental 3D localization accuracies in agreement with theoretical predictions and characterize the depth dependence of the localization accuracy in detail.

Optimizing monoscopic kV fluoro acquisition for prostate intrafraction motion evaluation

Monoscopic kV imaging during radiotherapy has been recently implemented for prostate intrafraction motion evaluation. However, the accuracy of 3D localization techniques from monoscopic imaging of prostate and the effect of acquisition parameters on the 3D accuracy have not been studied in detail, with imaging dose remaining a concern. In this paper, we investigate methods to optimize the kV acquisition parameters and imaging protocol to achieve improved 3D localization and 2D image registration accuracy for minimal imaging dose. Prostate motion during radiotherapy was simulated using existing cine-MRI measurements, and was used to investigate the accuracy of various 3D localization techniques and the effect of the kV acquisition protocol. We also investigated the relationship between mAs and the accuracy of the 2D image registration for localization of fiducial markers and we measured imaging dose for a 30 cm diameter phantom to evaluate the necessary dose to achieve acceptable image registration accuracy. Simulations showed that the error in assuming the shortest path to localize the prostate in 3D using monoscopic imaging during a typical IMRT fraction will be less than ∼1.5 mm for 95% of localizations, and will also depend on prostate motion distribution, treatment duration and image acquisition and treatment protocol. Most uncertainty cannot be reduced from higher imaging frequency or acquiring during gantry rotation between beams. Measured maximum surface dose to the cylindrical phantom from monoscopic kV intrafraction acquisitions varied between 0.4 and 5.5 mGy, depending on the acquisition protocol, and was lower than the required dose for CBCT (21.1 mGy). Imaging dose can be lowered by ∼15–40% when mAs is optimized with acquisition angle. Images acquired during MV beam delivery require increased mAs to obtain the same level of registration accuracy, with mAs/registration increasing roughly linearly with field size and dose rate.

Improved phase-contrast flow quantification by three-dimensional vessel localization

In this paper, a method of three-dimensional (3D) vessel localization is presented to allow the identification of a vessel of interest, the selection of a vessel segment, and the determination of a slice orientation to improve the accuracy of phase-contrast magnetic resonance (PCMR) angiography. A marching-cube surface-rendering algorithm was used to reconstruct the 3D vasculature. Surface-rendering was obtained using an iso-surface value determined from a maximum intensity projection (MIP) image. This 3D vasculature was used to find a vessel of interest, select a vessel segment, and to determine the slice orientation perpendicular to the vessel axis. Volumetric flow rate (VFR) was obtained in a phantom model and in vivo using 3D localization with double oblique cine PCMR scanning. PCMR flow measurements in the phantom showed 5.2% maximum error and a standard deviation of 9 mL/min during steady flow, 7.9% maximum error and a standard deviation of 13 mL/min during pulsatile flow compared with measurements using an ultrasonic transit-time flowmeter. PCMR VFR measurement error increased with misalignment at 10, 20, and 30 degrees oblique to the perpendicular slice in vitro and in vivo. The 3D localization technique allowed precise localization of the vessel of interest and optimal placement of the slice orientation for minimum error in flow measurements.

LocaLisa: new technique for real-time 3-dimensional localization of regular intracardiac electrodes.

Estimation of the 3-dimensional (3D) position of ablation electrodes from fluoroscopic images is inadequate if a systematic lesion pattern is required in the treatment of complex arrhythmogenic substrates. We developed a new technique for online 3D localization of intracardiac electrodes. Regular catheter electrodes are used as sensors for a high-frequency transthoracic electrical field, which is applied via standard skin electrodes. We investigated localization accuracy within the right atrium, right ventricle, and left ventricle by comparing measured and true interelectrode distances of a decapolar catheter. Long-term stability was analyzed by localization of the most proximal His bundle before and after slow pathway ablation. Electrogram recordings were unaffected by the applied electrical field. Localization data from 3 catheter positions, widely distributed within the right atrium, right ventricle, or left ventricle, were analyzed in 10 patients per group. The relationship between measured and true electrode positions was highly linear, with an average correlation coefficient of 0.996, 0.997, and 0.999 for the right atrium, right ventricle, and left ventricle, respectively. Localization accuracy was better than 2 mm, with an additional scaling error of 8% to 14%. After 2 hours, localization of the proximal His bundle was reproducible within 1.4+/-1.1 mm. This new technique enables accurate and reproducible real-time localization of electrode positions in cardiac mapping and ablation procedures. Its application does not distort the quality of electrograms and can be applied to any electrode catheter.

Accuracy of the localisa system in catheter ablation procedures

Estimation of the 3-dimensional (3D) position of ablation electrodes from fluoroscopic images is inadequate in the ablation of complex arrhythmogenic substrates. We developed a new technique for real-time 3D localization of intracardiac electrodes. Regular catheter electrodes are used as sensors for a high-frequency transthoracic electrical field, which is applied via standard skin electrodes. We investigated localization accuracy by comparing measured and true interelectrode distances between the tip and the 10th electrode of a decapolar catheter, and the tip and the 4th electrode of a quadripolar catheter during catheter ablation procedures. Long-term stability was analyzed by localization of the proximal His bundle before and after slow pathway ablation. Accuracy achieved with the 54-mm distance between the two outer electrodes of the decapolar catheters was 101% ± 15%, 95% ± 10%, and 97% ± 8% in the right atrium, right ventricle, and left ventricle, respectively. During catheter ablation procedures, the measured distance between the tip and 4th electrode of the mapping catheter was 100% ± 15% in atrial flutter, 100% ± 12% in slow pathway ablation, and 100% ± 14% in ablations for left ventricular tachycardia. After 2 hours, localization of the proximal His bundle was reproducible within 1.4 ± 1.1 mm. The LocaLisa technique allows for reproducible, real-time nonfluoroscopic 3D visualization of standard mapping and ablation catheters and is sufficiently accurate for the creation of linear radiofrequency lesions. The freedom of catheter choice makes the LocaLisa system an invaluable tool in catheter mapping and ablation procedures.

A new 3D localization technique using quadratic field gradients.

A new method of 3D spatial selection using pulsed quadratic field gradients is presented. Like previous pulsed quadratic gradient methods the new method requires only two RF pulses to achieve selection in three dimensions. Unlike previous methods, however, precise alignment of linear and quadratic gradient coils is not required. This characteristic allows the method to be used with small or surface quadratic gradient coils. The method is demonstrated on phantom and rats.