Edge Correction Research Articles

Fast computation of spatially adaptive kernel estimates

Kernel smoothing of spatial point data can often be improved using an adaptive, spatially varying bandwidth instead of a fixed bandwidth. However, computation with a varying bandwidth is much more demanding, especially when edge correction and bandwidth selection are involved. This paper proposes several new computational methods for adaptive kernel estimation from spatial point pattern data. A key idea is that a variable-bandwidth kernel estimator for d-dimensional spatial data can be represented as a slice of a fixed-bandwidth kernel estimator in $$(d+1)$$ -dimensional scale space, enabling fast computation using Fourier transforms. Edge correction factors have a similar representation. Different values of global bandwidth correspond to different slices of the scale space, so that bandwidth selection is greatly accelerated. Potential applications include estimation of multivariate probability density and spatial or spatiotemporal point process intensity, relative risk, and regression functions. The new methods perform well in simulations and in two real applications concerning the spatial epidemiology of primary biliary cirrhosis and the alarm calls of capuchin monkeys.

The influence of edge effects on the determination of the doping profile of silicon pad diodes

Edge effects for square p+n pad diodes with guard rings, fabricated on high-ohmic silicon, are investigated. Using capacitance-voltage measurements of two pad diodes with different areas, the planar and the edge contributions to the diode capacitance are determined separately. It is found that the edge contributions are significant and that they strongly influence the determination of the doping concentration using capacitance-voltage measurements. After edge correction, the bulk doping of the pad diodes is found to be uniform within ±1.5%, which agrees with expectations. The edge-correction method is verified using TCAD simulations of two circular pad diodes with different radii.

An efficient depth map preprocessing method based on structure-aided domain transform smoothing for 3D view generation.

Depth image-based rendering (DIBR), which is used to render virtual views with a color image and the corresponding depth map, is one of the key techniques in the 2D to 3D conversion process. Due to the absence of knowledge about the 3D structure of a scene and its corresponding texture, DIBR in the 2D to 3D conversion process, inevitably leads to holes in the resulting 3D image as a result of newly-exposed areas. In this paper, we proposed a structure-aided depth map preprocessing framework in the transformed domain, which is inspired by recently proposed domain transform for its low complexity and high efficiency. Firstly, our framework integrates hybrid constraints including scene structure, edge consistency and visual saliency information in the transformed domain to improve the performance of depth map preprocess in an implicit way. Then, adaptive smooth localization is cooperated and realized in the proposed framework to further reduce over-smoothness and enhance optimization in the non-hole regions. Different from the other similar methods, the proposed method can simultaneously achieve the effects of hole filling, edge correction and local smoothing for typical depth maps in a united framework. Thanks to these advantages, it can yield visually satisfactory results with less computational complexity for high quality 2D to 3D conversion. Numerical experimental results demonstrate the excellent performances of the proposed method.

Individual-Tree Competition Indices and Improved Compatibility with Stand-Level Estimates of Stem Density and Long-Term Production

When explaining the dynamics of individual trees, the incorporation of size and distance of neighboring trees into a model can improve the prediction of growth and mortality. Several methods have been proposed to define the number of competing trees based on variable zone radii and the principles of angle count sampling. The task of measuring position-dependent competition indices appears to be ideally suited for permanent sample plots and long-term studies of growth and yield (production), where the marginal effort of remeasurement is concentrated on measuring size attributes of survivor trees and the occasional distance of a new sample tree. The proposed competition index is based on point sampling with a variable basal area factor (BAFV) that is partially derived from the Spurr (1962) competition index. Point sampling is a fast, easy, and inexpensive methodology for selecting the number of competing trees, and the new BAFV methodology proved to be very efficient for estimating growth. With the selection of an appropriate basal area factor, it is possible to reduce the number of subject trees and competition trees in the sample, and eliminate the need for edge correction methods. Although the index value assigned to the subject tree using the BAFV is biased, an appropriate correction is presented and discussed. The average competition index obtained from using the corrected value for the subject tree and the BAFV for the competing trees equals the stand level estimate of basal area.

Resonant enhancement in nanostructured thermoelectric performance via electronic thermal conductivity engineering

The use of an asymmetric broadening in the transport distribution, a characteristic of resonant structures, is proposed as a route to engineer a decrease in electronic thermal conductivity thereby enhancing the electronic figure of merit in nanostructured thermoelectrics. Using toy models, we first demonstrate that a decrease in thermal conductivity resulting from such an asymmetric broadening may indeed lead to an electronic figure of merit well in excess of 1000 in an idealized situation and in excess of 10 in a realistic situation. We then substantiate with realistic resonant structures designed using graphene nano-ribbons by employing a tight binding framework with edge correction that match density functional theory calculations under the local density approximation. The calculated figure of merit exceeding 10 in such realistic structures further reinforces the concept and sets a promising direction to use nano-ribbon structures to engineer a favorable decrease in the electronic thermal conductivity.

In vivo validation of gated myocardial SPECT imaging for quantification of small hearts: comparison with cardiac MRI.

BackgroundIn patients with small hearts, the Quantitative Gated single-photon emission computed tomography (SPECT) (QGS) program frequently underestimates the left ventricular (LV) end-systolic volume (ESV) and overestimates the ejection fraction (EF). A newly developed cardiac software program, cardioREPO/EXINI heart (cREPO), has been proposed to more accurately quantify small hearts using active shape modeling and a volume-dependent edge correction algorithm for LV delineation. The aim of this study was to validate cREPO in vivo for measuring the LV volumes and EF of both small and non-small hearts, in comparison with values obtained via cardiac MRI (CMR).MethodsWe performed stress 99mTc-MIBI SPECT and CMR within a 30-day interval for 44 patients (mean age, 66 years; 27 men). Resting EF, end-diastolic volume (EDV), and ESV with QGS and cREPO were compared with values obtained via CMR.ResultsThe subjects consisted of 17 small and 27 non-small hearts. CMR yielded EDV, ESV, and EF values of 135 ± 31 ml (mean ± SD, range 85–217 ml), 57 ± 21 ml (27–105 ml), and 60 ± 6 % (45–70 %), respectively. Compared with CMR, both QGS and cREPO systematically underestimated both EDV and ESV and overestimated EF. The magnitude of the overestimation of EF by QGS, compared with CMR, correlated strongly with the given EF values (r = 0.71, P < 0.0001). In contrast, no significant correlation was seen with cREPO (r = 0.18, P = 0.24). In addition, no significant correlation was found between the magnitude of the underestimation of ESV and heart size with cREPO (r = 0.03, P = 0.83). Thus, cREPO provided a relatively constant 9 % overestimation of EF values relative to CMR, for the studied EF range for both small and non-small hearts.ConclusionsThe use of the new algorithm of cREPO ameliorated exaggerated EF in small hearts but not resolved completely. The program provided a constant 9 % overestimation for both small and non-small hearts, which should be carefully taken into account for clinical assessment of LV function.

An evaluation of the state of spatial point pattern analysis in ecology

Over the last two decades spatial point pattern analysis (SPPA) has become increasingly popular in ecological research. To direct future work in this area we review studies using SPPA techniques in ecology and related disciplines. We first summarize the key elements of SPPA in ecology (i.e. data types, summary statistics and their estimation, null models, comparison of data and models, and consideration of heterogeneity); second, we review how ecologists have used these key elements; and finally, we identify practical difficulties that are still commonly encountered and point to new methods that allow current key questions in ecology to be effectively addressed.Our review of 308 articles published over the period 1992–2012 reveals that a standard canon of SPPA techniques in ecology has been largely identified and that most of the earlier technical issues that occupied ecologists, such as edge correction, have been solved. However, the majority of studies underused the methodological potential offered by modern SPPA. More advanced techniques of SPPA offer the potential to address a variety of highly relevant ecological questions. For example, inhomogeneous summary statistics can quantify the impact of heterogeneous environments, mark correlation functions can include trait and phylogenetic information in the analysis of multivariate spatial patterns, and more refined point process models can be used to realistically characterize the structure of a wide range of patterns. Additionally, recent advances in fitting spatially‐explicit simulation models of community dynamics to point pattern summary statistics hold the promise for solving the longstanding problem of linking pattern to process. All these newer developments allow ecologists to keep up with the increasing availability of spatial data sets provided by newer technologies, which allow point patterns and environmental variables to be mapped over large spatial extents at increasingly higher image resolutions.

Post-processing Technique for Improving the Odor-identification Performance based on E-Nose System

In this paper, we proposed a post-processing technique for improving classification performance of electronic nose (E-Nose) system which may be occurred drift signals from sensor array. An adaptive radial basis function network using stochastic gradient (SG) and singular value decomposition (SVD) is applied to process signals from sensor array. Due to drift from sensor's aging and poisoning problems, the final classification results may be showed bias and fluctuations. The predicted classification results with drift are quantized to determine which identification level each class is on. To mitigate sharp fluctuations moving-averaging (MA) technique is applied to quantized identification results. Finally, quantization and some edge correction process are used to decide levels of the fluctuation-smoothed identification results. The proposed technique has been indicated that E-Nose system was shown correct odor identification results even if drift occurred in sensor array. It has been confirmed throughout the experimental works. The enhancements have produced a very robust odor identification capability which can compensate for decision errors induced from drift effects with sensor array in electronic nose system.

Computing the three-point correlation function of galaxies in $\mathcal {O}(N^2)$ time

We present an algorithm that computes the multipole coefficients of the galaxy three-point correlation function (3PCF) without explicitly considering triplets of galaxies. Rather, centering on each galaxy in the survey, it expands the radially-binned density field in spherical harmonics and combines these to form the multipoles without ever requiring the relative angle between a pair about the central. This approach scales with number and number density in the same way as the two-point correlation function, allowing runtimes that are comparable, and 500 times faster than a naive triplet count. It is exact in angle and easily handles edge correction. We demonstrate the algorithm on the LasDamas SDSS-DR7 mock catalogs, computing an edge corrected 3PCF out to $90\;{\rm Mpc}/h$ in under an hour on modest computing resources. We expect this algorithm will render it possible to obtain the large-scale 3PCF for upcoming surveys such as Euclid, LSST, and DESI.

Efficient Electromagnetic Scattering Computation Using the Random Auxiliary Sources Method for Multiple Composite 3-D Arbitrary Objects

The electromagnetic (EM) scattering problem from three-dimensional (3-D) arbitrary composite objects is proposed using the random auxiliary sources (RAS) method. Based on direct application of the boundary conditions with the uniqueness theorem and the use of random equivalent problems concept, more degrees-of-freedom to the sources’ positions are added resulting in significantly efficient solutions with lower memory requirements. The technique does not require any singularity treatment due to placing the equivalent sources away from the boundaries. While boundary conditions are not enforced exactly, an iterative framework is introduced that can achieve an acceptable level of error in their satisfaction for an arbitrary, randomly generated set of equivalent sources. The presented technique promises a significant reduction in the execution time and memory requirements compared to the surface-equivalent-based method of moments (MoM). The solution stability, repeatability, and numerical noise susceptibility are investigated thoroughly through this work. Also, a novel edge correction scheme has been implemented to extend the capabilities of this procedure to structures with sharp edges. The results of the presented technique are compared to series solutions for conducting spheres and a commercially available MoM code for arbitrarily shaped objects and combinations of different materials.

New shadow detection and removal approach to improve neural stereo correspondence of dense urban VHR remote sensing images

Shadows cause problems in many remote sensing applications like images segmentation, objects extraction and stereo vision. This paper presents a new and an automatic approach to detect and remove shadows from pair of dense urban very high resolution (VHR) remote sensing images. The main contribution of this paper is twofold. First, a proposed approach is efficient to restore objects hidden by shadows, second, it improves a stereo matching process. We have chosen to operate on Ikonos pairs as an example of urban remote sensing images, for that, shadow detection is achieved using a new technique of property based method, operating directly in red. green and blue colour space (RGB). Shadow removal proposed technique aims to produce a needed amount of light to the shadow regions by multiplying the shadow regions by constants, after that, the shadow edge correction is applied to reduce the errors due to diffusion in the shadow boundary. Once pair of shadow free images is recovered, we apply a stereo matching process using a Hopfield neural technique in order to find homologous regions. Our results from different urban pairs show the effectiveness, the simplicity and the fastness of the proposed approach to reveal details hidden by shadows and to obtain a high stereo matching rate.

An Optimized Track Length in Roadway Inductive Power Transfer Systems

Application of inductive power transfer (IPT) to electric vehicles moving along the road can provide more charging flexibility with the reduction of weight and size of charge-storage batteries required in the vehicles. Existing research focuses on the efficiency improvement and alignment tolerance of the IPT transformer. Consideration of the transformer track length and the vehicle speed is rarely discussed. In this paper, an IPT vehicle charging system using a series of sectional tracks is studied. The relationship among various key parameters, such as vehicle speed, system efficiency, and power utilization of the IPT system, is studied in detail. Specifically, the impact on efficiency due to variation of track length and edge correction is reported. The extension of the system from a single pickup to multiple pickups is discussed. The results are verified with finite-element-analysis simulation and a scale-down experimental prototype.

Two-dimensional in vivo dose verification using portal imaging and correlation ratios.

The electronic portal imaging device (EPID) has the potential to be used for in vivo dosimetry during radiation therapy as an additional dose delivery check. In this study we have extended a method developed by A. Piermattei and colleagues in 2006 that made use of EPID transit images (acquired during treatment) to calculate dose in the isocenter point. The extension allows calculation of two‐dimensional dose maps of the entire radiation field at the depth of isocenter. We quantified the variability of the ratio of EPID signal to dose in the isocenter plane in Solid Water phantoms of various thicknesses and with various field sizes, and designed a field edge dose calculation correction. To validate the method, we designed three realistic conventional radiation therapy treatment plans on a thorax and head anthropomorphic phantom (whole brain, brain primary, lung tumor). Using CT data, EPID transit images, EPID signal‐to‐dose correlation, and our edge correction, we calculated dose in the isocenter plane and compared it with the treatment planning system's prediction. Gamma evaluation (3%, 3 mm) showed good agreement (Pγ<1 ≥ 96.5%) for all fields of the whole brain and brain primary plans. In the presence of lung, however, our algorithm overestimated dose by 7%–9%. This 2D EPID‐based in vivo dosimetry method can be used for posttreatment dose verification, thereby improving the safety and quality of patient treatments. With future work, it may be extended to measure dose in real time and to prevent harmful delivery errors.PACS numbers: 87.55.km, 87.55.Qr, 87.55.T‐

Real-time critical dimension measurement of thin film transistor liquid crystal display patterns using optical coherence tomography

A coherence scanning tomographic imaging system with an innovative signal correction method is presented for a critical dimension (CD) measurement of thin film transistor liquid crystal display patterns having multiple focus positions within a single field of view. To facilitate the analyzing of coherence signals, a simulation model based on fast Fourier transform method is proposed, and its simulated result is compared with the coherence signals from the actual experiments. The comparison shows that the majority of frequency characteristics from simulation modeling results are matched with the experimental results. However, in many edge regions, discrepancies in frequency characteristics between the two results are observed. For the interpretation of signals, those are different from the simulation modelling, in that the intensity of its pixels has been corrected by an innovatively proposed connected neighborhoods window method with multiple window sizes. By using this combination of tomographic imaging and edge correction methods, the repeatability of the CD measurement of multiple focus position samples is significantly enhanced compared to the results with a plain two-dimensional optics. The proposed method is also compared with the autofocus methods including gradient magnitude method and frequency domain method and other tomographic imaging methods, including the phase shift method and the Hilbert transform method to show the advantages in the processing time.

Video resampling algorithm for simultaneous deinterlacing and image upscaling with reduced jagged edge artifacts

Abstract In this paper, we propose a video resampling method for simultaneous deinterlacing and image upscaling. The proposed method is composed of two steps: the initial image magnification step and the edge enhancement step. In order to convert an interlaced image into a display format image, a filtering strategy, which resizes images with arbitrary ratios and reduces the overall computational load, is performed region adaptively using local characteristics such as motion or motionless regions. After the initial step, the proposed jagged edge correction (JEC) method is applied to the initially upscaled images to correct the stair-like artifacts (jagged edges) which are caused by ignoring any edge information in diagonal edge regions during the linear filtering process. Moreover, this method can be very useful for various upscaling applications to improve edge quality since it can be used in combination with other common interpolation techniques, such as cubic spline techniques. Experimental results show that the proposed method substantially reduces the jagged edges of the converted images and provides steep and natural-looking edge transitions.

Statistical Beaconing Congestion Control for Vehicular Networks

Cooperative intervehicular applications rely on the periodic exchange of broadcast single-hop status messages among vehicles, which are called beacons. The aggregated load on a wireless channel due to beacons can prevent the transmission of other types of messages, which is called channel congestion due to beaconing activity. In this paper, we propose a novel statistical approach to transmit power control (TPC) for beaconing congestion control, which is called statistical beaconing congestion control (SBCC). Unlike previous proposals, SBCC uses local information and very limited feedback, and its implementation is simple. Each vehicle locally computes the power needed to comply with a given maximum beacon load as a function of estimated channel parameters, vehicle density, and beaconing rate. A realistic Nakagami- <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$m$</tex></formula> fading and path-loss propagation model is assumed. We provide a final expression of the algorithm as a linear proportional controller, with two variants, i.e., channel-busy-time-(CBT) based SBCC (SBCC-C) and neighbor-based SBCC (SBCC-N), depending on how the parameters are estimated. Additionally, we derive an expression for the estimated communication range under interference, which approximates the average fraction of packets lost due to hidden-node collisions. Finally, we evaluate the performance degradation caused by differences in local vehicle densities and propose a mechanism, which is called edge correction (EC), to limit it while keeping the safety benefits of an extended range at the edge of a cluster of vehicles. SBCC is validated with a realistic hybrid network-traffic simulator, and results show that it effectively controls beaconing congestion.

Estimating Second-Order Characteristics of Inhomogeneous Spatio-Temporal Point Processes

Non-parametric estimates of the K-function and the pair correlation function play a fundamental role for exploratory and explanatory analysis of spatial and spatio-temporal point patterns. These estimates usually require information from outside of the study region, resulting to the so-called edge effects which have to be corrected. They also depend on first-order characteristics, which have to be estimated in practice. In this paper, we extend classical edge correction methods to the spatio-temporal setting and compare the performance of the related estimators for stationary/non-stationary and/or isotropic/anisotropic point patterns. Further, we explore the influence of the estimated intensity function on these estimators.

Data De-noising Based on PCA-KNN Algorithm in Billet Surface Temperature Measurement

This paper first analyzes the soft-sensor technology and temperature measurement technology used in recent soft measurements, focuses on the accuracy and efficiency requirements of soft measurement in slab surface temperature detection. In this paper, we collects images noise processes of continuous casting slabs, and uses component-based OTSU segmentation method to extract the slab area and then implements Hough transform for edge correction; then measures the selected regions of interest in pixels and extracts color features using PCA for feature reduction; we extracts the improved data set with KNN algorithm for noise reduction, and the removal of contradictory data; the final regression models are used in prediction.

SU‐E‐J‐186: Automated SPECT‐Based Segmentation for Quality Assurance of CT‐Delineated Tumor Volumes for 131I Tositumomab Therapy of Non‐Hodgkins Lymphoma

Purpose: CT segmentation of tumor volumes suffers from many error sources which can impact the calculation of absorbed dose and 4D bio‐effect modeling. Determination of gross tumor volumes from SPECT scans of anti‐CD20 monoclonal antibody uptake was explored as a quality assurance step. Investigated were two count threshold methods (optimal and constant threshold) and one edge detection method. Methods: Patient data were selected from a dataset of refractory non‐Hodgkins lymphoma studies of 131I radioimmunotherapy. The calibration phantom geometry consisted of seven (1 mL to 95 mL) spheres in an elliptical tank. The background activity was 5 mCi with sphere activities adjusted for an approximate 6:1 concentration ratio. Phantom scans were repeated with no background activity. The patient and calibration sphere data were collected on a Siemens Symbia TruePoint SPECT/CT scanner and reconstructed with in‐house OS‐EM software. The optimal threshold technique used a calibration of threshold vs volume. The constant threshold method (40% and 60% thresholds explored) used a calibration of volume correction factor vs volume. The edge detection method used the Canny algorithm to map edges and determine an edge correction factor. Results: Challenges included 1) resolving tumor volume from nearby significant uptake objects (organs, vessels or other tumors) and 2) identifying volume for large tumors with significantly non‐uniform activity. A constant threshold of 60% with background and volume correction performed best. The determined volumes from patient data were 0.70–0.73 (&gt;12mL) or 0.44‐0.69 (&lt;12mL) of the CT‐delineated volumes. The lower than unity values were attributed to non‐sharp activity boundaries. A priori volume estimates were required for object radii less than the scanner resolution (i.e. &lt;12mL). Conclusion: The constant threshold method can be used to check the validity of CT‐delineated tumor volumes. An additional volume correction factor is required to account for non‐sharp tumor edges. Dr M Kaminski receives research support from GlaxoSmithKline and royalties from Bexxar.

Improved quantification of small hearts for gated myocardial perfusion imaging

PurposeIn patients with a small heart, defined as an end-systolic volume (ESV) of ≤20 mL calculated using the Quantitative Gated SPECT (QGS) program, underestimation of ESV and overestimation of ejection fraction (EF) using gated myocardial perfusion imaging are considered errors caused by inappropriate delineation of the left ventricle (LV). The aim of this study was to develop a new method for delineation of the LV and to evaluate it in studies using a digital phantom, normal subjects and patients.MethodsThe active shape-based method for LV delineation, EXINI heart (ExH), was adjusted to more accurately process small hearts. In small hearts, due to the partial volume effect and the short distance to the opposite ventricular wall, the endocardial and the epicardial surfaces are shifted in the epicardial direction depending on the midventricular volume. The adjusted method was evaluated using digital XCAT phantoms with Monte Carlo simulation (8 virtual patients), a Japanese multicentre normal database (69 patients) and consecutive Japanese patients (116 patients). The LV volumes, EF and diastolic parameters derived from ExH and QGS were compared.ResultsThe digital phantom studies showed a mean ESV of 87 % ± 9 % of the true volume calculated using ExH and 22 % ± 18 % calculated using QGS. In the normal database, QGS gave higher EFs in women than in men (71.4 ± 6.0 % vs. 67.2 ± 6.0 %, p = 0.0058), but ExH gave comparable EFs (70.7 ± 4.9 % and 71.4 ± 5 % in men and women, respectively, p = ns). QGS gave higher EFs in subjects with a small heart than in those with a normal-sized heart (74.5 ± 5.1 % vs. 66.1 ± 4.9 %), but ExH gave comparable values (70.0 ± 5.9 % vs. 71.6 ± 4.2 %, respectively, p = ns). In consecutive patients, the average EFs with QGS in patients with ESV >20 mL, 11–20 mL and ≤10 mL were 57.9 %, 71.9 % and 83.2 %, but with ExH the differences among these groups were smaller (65.2 %, 67.8 % and 71.5 %, respectively).ConclusionThe volume-dependent edge correction algorithm was able to effectively reduce the effects on ESV and EF of a small heart. The uniform normal values might be applicable to both men and women and to both small and normal-sized hearts.