Time-sequential Images Research Articles

Location monitoring approach of underground pipelines using time-sequential images

The location monitoring of underground pipelines is of utmost significance as it helps the effective management and maintenance of the pipelines, and facilitates the planning of nearby projects, preventing damage to the pipelines. However, currently there is a serious lack of data on the locations of underground pipelines. This paper proposes an image-based approach for monitoring the locations of underground pipelines by combing deep learning and visual-based reconstruction. The proposed approach can build the monitoring model for underground pipelines and characterize their locations through their centroid curve. Its advantages are: (1) simplicity: it only requires time-sequential images of the inner walls of underground pipelines; (2) clarity: the location model and the location curve of underground pipelines can be provided quickly; (3) robustness: it can cope with some existing problems in underground pipelines, such as light variations and small viewing angles. A lightweight approach for monitoring the locations of underground pipelines is achieved. The proposed approach’s effectiveness has been validated through laboratory simulation experiments, demonstrating accuracy at the millimeter level.

Simultaneous imaging of prompt gamma photons and prompt X-rays during irradiation of proton beams to human torso phantom at clinical dose level

Although both prompt gamma photon and prompt X-ray imaging are promising methods for observing a beam shape and estimating the range of the beam from outside a subject, the images using these two methods have not been compared under realistic conditions such as in a human torso phantom. To clarify the imaging capability of prompt gamma photon and prompt X-ray imaging, simultaneous imaging with these methods was conducted during irradiation by proton beams to a human torso phantom at clinical dose level. After a human torso phantom was set on the bed of a proton therapy system, proton pencil beams of three different energies at clinical dose level and a patient planning beam for prostate cancer were used to irradiate the phantom. Prompt gamma photons and prompt X-rays emitted from the phantom were simultaneously imaged by a developed gamma camera and an X-ray camera during irradiation with proton beams to the human torso phantom. For all of the tested beams, we could obtain the beam shapes of prompt gamma photons and prompt X-rays images. The ranges could be estimated within a difference of 11 mm and 14 mm from the calculated dose for prompt gamma photon and prompt X-ray images, respectively. For both types of images, time sequential images and time count rate curves could be derived. We could clarify the imaging capabilities of prompt gamma photons and prompt X-rays were different by the simultaneous imaging during proton irradiation to a human torso phantom. Although both methods had advantages and disadvantages, we confirmed that both methods are promising for beam imaging in a torso phantom and also for future clinical use in proton therapy.

Hybrid imaging of prompt x-rays and induced positrons using a pinhole gamma camera during and after irradiation of protons

Objective. Prompt x-ray imaging using a low-energy x-ray camera is a promising method for observing a proton beam’s shape from outside the subject. Furthermore, imaging of positrons produced by nuclear reactions with protons is a possible method for observing the beam shape. However, it has not been possible to measure these two types of images with a single imaging system due to the limited imaging capability of existing systems. Imaging of both prompt x-rays and the distribution of positrons may compensate for the shortcomings of each method. Approach. We conducted imaging of the prompt x-ray using a pinhole x-ray camera during irradiation with protons in list mode. Then, after irradiation with protons, imaging of annihilation radiations from the produced positrons was conducted using the same pinhole x-ray camera in list mode. After this imaging, list-mode data were sorted to obtain prompt x-ray images and positron images. Main results. With the proposed procedure, we could measure both prompt x-ray images and induced positron images with a single irradiation by a proton beam. From the prompt x-ray images, ranges and widths of the proton beams could be estimated. The distributions of positrons were slightly wider than those of the prompt x-rays. From the time sequential positron images, we could derive the time activity curves of the produced positrons. Significance. Hybrid imaging of prompt x-rays and induced positrons using a pinhole x-ray camera was achieved. The proposed procedure would be useful for measuring prompt x-ray images during irradiation to estimate the beam structures as well as for measuring the induced positron images after irradiation to estimate the distributions and time activity curves of the induced positrons.

Short time sequential luminescence imaging of water during irradiation by protons

Abstract Although luminescence imaging of water during irradiation by particle ions is a promising method for dose estimation, it has only been tried for static images in which temporal information is not included. In addition to the positional distribution of the beam, temporal information is also important because the beams from a synchrotron-based therapy system have short pulse shapes called spills. The temporal information is also important for high dose rate, short-time radiotherapy, or so-called FLASH radiotherapy. To measure the particle ion beam distributions with precise temporal information, we conducted short time sequential luminescence imaging of protons. First, we measured short time sequential luminescence images during irradiation of a water phantom by 150-MeV protons using a cooled charge-coupled device (CCD) camera at 0.143-s intervals. With this imaging, the images showed beam distributions, but the shapes of the spill were not precisely evaluated in time intensity curves due to the insufficient sampling rate of the imaging. Then we measured short time sequential optical images with 0.053-s intervals. With this imaging, the images showed that the beam distributions in the spill shape could be measured, but the image and depth profiles evaluated from the images were noisy due to the insufficient light intensity. Consequently, we measured short time sequential luminescence images during irradiation of fluorescein (FS) water by 150-MeV protons. Since FS water produced ∼10 times higher luminescence, we could obtain high-intensity images enabling us to evaluate the time intensity curves based on the shape of the spills during measurement with 0.053-s intervals. The depth profiles of the beam were also obtained from the measured images. With these results, we confirmed that time sequential luminescence imaging was possible and, in such cases, FS water images measured at 0.053-s intervals are most promising to measure the short time sequential luminescence images during irradiation of protons.

Atmospheric muography for imaging and monitoring tropic cyclones

Large-scale solid bodies on Earth such as volcanoes and man-made pyramids have been visualized with solid earth muography, and the recently invented technique, acqueous muography, has already demonstrated its capability to visualize ocean tides and tsunami. In this work, atmospheric muography, a technique to visualize and monitor the vertical profile of tropic cyclones (TCs) is presented for the first time. The density distribution and time-dependent behavior of several TCs which had approached Kagoshima, Japan, has been investigated with muography. The resultant time-sequential images captured their warm cores, and their movements were consistent with the TC trails and barometric pressure variations observed at meteorological stations. By combining multidirectional muographic images with barometric data, we anticipate that muography will become a useful tool to monitor the three-dimensional density distribution of a targeted mesoscale convective system.

Technical note: Short-time sequential high-energy gamma photon imaging using list-mode data acquisition system for high-dose-rate brachytherapy.

Measurement of the dwell time and moving speed of a high-activity iridium-192 (Ir-192) source used for high-dose-rate (HDR) brachytherapy is important for estimating the precise dose delivery to a tumor. For this purpose, we used a cerium-doped yttrium aluminum perovskite (YA1O3 :YAP(Ce)) gamma camera system, combined with a list-mode data acquisition system that can acquire short-time sequential images, and measured the dwell times and moving speeds of the Ir-192 source. Gamma photon imaging was conducted using the gamma camera in list mode for the Ir-192 source of HDR brachytherapy with fixed dwell times and positions. The acquired list-mode images were sorted to millisecond-order interval time sequential images to evaluate the dwell time at each position. Time count rate curves were derived to calculate the dwell time at each source position and moving speed of the source. We could measure the millisecond-order time sequential images for the Ir-192 source. The measured times for the preset dwell times of 2 s and 10 s were 1.98 to 2.00 s full width at half maximum (FWHM) and 10.0 s FWHM, respectively. The dwell times at the first dwell position were larger than those at other positions. We also measured the moving speeds of the source after the dwells while moving back to the afterloader and found the speed increased with the distance from the edge of the field of view to the last dwell position. We conclude that millisecond-order time sequential imaging of the Ir-192 source is possible by using a gamma camera and is useful for evaluating the dwell times and moving speeds of the Ir-192 source.

Rate of spread and flaming zone velocities of surface fires from visible and thermal image processing

This study presents two new remote sensing approaches that can be used to derive rate of spread and flaming zone velocities of a wildfire at very high spatiotemporal resolution. Time sequential image tracking from thermal or visible video collected on uncrewed aerial vehicles is used to estimate instantaneous spatial rate of spread of a surface fire. The techniques were developed using experimental wheat‐stubble burns carried out near Darfield, New Zealand, in March 2019. The thermal tracking technique is based on Thermal Image Velocimetry, which tracks evolving temperature patterns within an infrared video. The visible tracking technique uses colour thresholding, and tracks fire perimeter progression through time at pixel resolution. Results show that the visible perimeter tracking creates a higher mean rate of spread compared to thermal image velocimetry. The visible perimeter tracking provides rate of spread measurements for fire front progression whereas the thermal tracking techniqueis computationally more expensive, but can resolve velocities of thermal structures within the flaming zone and provides spatiotemporal rate of spread measurements. Both techniques are available as open‐source code and providevital scientific data for new studies concerning e.g. fire–atmospheric interactions or model validation. They may be adapted for operational purposes providing rate of spread at high spatiotemporal resolution.

Pupil replication waveguide system for autostereoscopic imaging with a wide field of view.

Augmented reality head-up displays (HUDs) require virtual-object distance matching to the real scene along an adequate field of view (FoV). At the same time, pupil-replication-based waveguide systems provide a wide FoV while affording compact HUDs. To provide 3D imaging and enable virtual-object distance matching in such waveguide systems, we propose a time-sequential autostereoscopic imaging architecture using a synchronized multi-view picture generation and eyebox formation units. Our simulation setup to validate the system feasibility yields an FoV of 15° × 7.5° with clear crosstalk-less images with a resolution of 60 pix/deg for each eye. Our proof-of-concept prototype with reduced specs yields results that are consistent with the simulation in terms of the viewing-zone formation. Thus, viewing zones for the left and right eyes in plane of the eyebox can be clearly observed. Finally, we discuss how the initial distance of the virtual image can be set for quantified fatigue-free 3D imaging, and an FoV can be further extended in such types of waveguide systems by varying parameters of the eyebox formation unit.

Dynamics of wetting transition of initially hydrocarbon-filled microscopic cavities replaced with water

Studies on the behavior of liquids on rough surfaces have been extensive and provided much insight into scientific and industrial applications such as superhydrophobicity and contact angle hysteresis. However, most of these studies deal with solid-liquid-vapor systems (SLV) at equilibrium, with much less attention given to the dynamics of wetting transition with solid-liquid-liquid systems (SL1L2). They are as common as SLV, such as in enhanced oil recovery with low-salinity water flooding, and medicinal creams on porous skins. Therefore, this report aims to investigate the factors that control the rate of wetting transition or replacement where initially oil-filled cavities are replaced with water, under the hypothesis that the density difference and the adhesion energy would control the rate. To this purpose, seven common hydrocarbons with fluorescent dyes were individually placed inside 60-μm wide and 10-μm deep cylindrical cavities etched on silicon wafers followed by immersing them under (1) deionized water and (2) water saturated with each hydrocarbon. By making time-sequential images of the cavities and statistical analyses, the factors affecting the rate of replacement were determined. The experiments with deionized water revealed that solubility and diffusivity were the driving factors that promoted the replacement, and the 3D confocal images confirmed the decrease in volume of hydrocarbons due to dissolution and diffusion. To exclude these factors, water was saturated with each of the seven hydrocarbons prior to experiments. For these experiments, the adhesion energy of hydrocarbons to the solid surface and the density difference between hydrocarbons and water were correlated with the rate as originally hypothesized.

Mapping lead concentrations in urban topsoil using proximal and remote sensing data and hybrid statistical approaches.

Due to rapid urbanization in China, lead (Pb) continues to accumulate in urban topsoil, resulting in soil degradation and increased public exposure. Mapping Pb concentrations in urban topsoil is therefore vital for the evaluation and control of this exposure risk. This study developed spatial models to map Pb concentrations in urban topsoil using proximal and remote sensing data. Proximal sensing reflectance spectra (350-2500nm) of soils were pre-processed and used to calculate the principal components as landscape factors to represent the soil properties. Other landscape factors, including vegetation and land-use factors, were extracted from time-sequential Landsat images. Two hybrid statistical approaches, regression kriging (RK) and geographically weighted regression (GWR), were adopted to establish prediction models using the landscape factors. The results indicated that the use of landscape factors derived from combined remote and proximal sensing data improved the prediction of Pb concentrations compared with useing these data individually. GWR obtained better results than RK for predicting soil Pb concentration. Thus, joint proximal and remote sensing provides timely, easily accessible, and suitable data for extracting landscape factors.

Dynamic Capture and Release of Endoplasmic Reticulum Exit Sites by Golgi Stacks in Arabidopsis.

SummaryProtein transport from the endoplasmic reticulum (ER) to Golgi stacks is mediated by the coat protein complex COPII, which is assembled at an ER subdomain called ER exit site (ERES). However, the dynamic relationship between ERESs and Golgi stacks is unknown. Here, we propose a dynamic capture-and-release model of ERESs by Golgi stacks in Arabidopsis thaliana. Using variable-angle epifluorescence microscopy with high-temporal-resolution imaging, COPII-component-bound ERESs were detected as punctate structures with sizes of 300–500 nm. Some punctate ERESs are distributed on ER tubules and sheet rims, whereas others gather around a Golgi stack in an ER-network cavity to form a beaded-ring structure. Free ERESs that wander into an ER cavity are captured by a Golgi stack in a cytoskeleton-independent manner. Then, they are released by the Golgi stack for recycling. The dynamic ERES cycling might contribute to efficient transfer of de novo synthesized cargo proteins from the ER to Golgi stacks.

Light-Field Camera for Fast Switching of Time-Sequential Two-Dimensional and Three-Dimensional Image Capturing at Video Rate

In this article, we propose a time-sequential switching light-field (LF) camera for an alternative image capture of the high-resolution two-dimensional (2-D) images and three-dimensional (3-D) LF elemental images as additional functionalities. For image data acquisitions of both the 2-D and 3-D LF imaging of moving objects at a video frame rate (or even higher frame rate up to approximately 1000 f/s), a polarization-dependent-switching microlens array (MLA) is implemented in the LF camera system instead of a conventional passive-type MLA. By controlling the incident polarization conditions using an electrically fast-switching liquid crystal layer, the imaging mode can be time-sequentially switched quite rapidly (switching times of approximately 220 and 290 μ s for the mode conversions from the 3-D LF to the 2-D mode, and the reversal mode change, respectively). Using the elemental image sets sampled from the alternating time-sequential imaging results, either the directional-view images or depth-refocused images can be reconstructed and provided at a moving picture frame rate. The depth-refocused images are possible for a wide depth range from 25 to 350 cm. Directional views of 22 × 22 and 9 × 9 in portions can be reconstructed for the single-shot image capture and the time-sequential video-rate image capture, respectively.

Assessing uncertainty and demonstrating potential for estimating fire rate of spread at landscape scales based on time sequential airborne thermal infrared imaging

ABSTRACTAn important property of wildfire behaviour is rate of spread (ROS). The objectives of this study are to evaluate the uncertainty of landscape-scale ROS estimates derived from repetitive airborne thermal infrared (ATIR) georeferenced imagery and the utility of such estimates for understanding fire behaviour and controls on spread rates. Time-sequential ATIR image data were collected for the Cedar, Detwiler, and Rey Fires, which burned in California during summers of 2016 and 2017. We analyse error, uncertainty, and precision of ROS estimates associated with co-location accuracy, delineation of active fire front positions, and generation of fire spread vectors. The major sources of uncertainty influencing accuracy of ROS estimates are co-registration accuracy of sequential image pairs and procedures for delineating active fire front locations and spread vectors between them; none of these were found to be substantial. Median ROS estimates are 11 m min−1 for the Cedar Fire and 8 m min−1 for the Detwiler Fire, both of which burned through mixed shrub and tree areas of the Sierra Nevada foothills and were estimated for downslope spread events. Of the three study fires, the fastest spread rates (average spread of 25 m min−1 with maximum of 39 m min−1) are estimated for the Rey Fire, which burned on variable directional slopes through chaparral shrubland vegetation.

Proactive Received Power Prediction Using Machine Learning and Depth Images for mmWave Networks

This study demonstrates the feasibility of the proactive received power prediction by leveraging spatiotemporal visual sensing information toward the reliable millimeter-wave (mmWave) networks. Since the received power on a mmWave link can attenuate aperiodically due to a human blockage, the long-term series of the future received power cannot be predicted by analyzing the received signals before the blockage occurs. We propose a novel mechanism that predicts a time series of the received power from the next moment to even several hundred milliseconds ahead. The key idea is to leverage the camera imagery and machine learning (ML). The time-sequential images can involve the spatial geometry and the mobility of obstacles representing the mmWave signal propagation. ML is used to build the prediction model from the dataset of sequential images labeled with the received power in several hundred milliseconds ahead of when each image is obtained. The simulation and experimental evaluations using IEEE 802.11ad devices and a depth camera show that the proposed mechanism employing convolutional LSTM predicted a time series of the received power in up to 500 ms ahead at an inference time of less than 3 ms with a root-mean-square error of 3.5 dB.

High-speed optical 3D sensing and its applications

Abstract This paper reviews high-speed optical 3D sensing technologies for obtaining the 3D shape of a target using a camera. The focusing speed is from 100 to 1000 fps, exceeding normal camera frame rates, which are typically 30 fps. In particular, contactless, active, and real-time systems are introduced. Also, three example applications of this type of sensing technology are introduced, including surface reconstruction from time-sequential depth images, high-speed 3D user interaction, and high-speed digital archiving.

Application to skin physiology using optical coherence tomography.

Background and aims: The sweat glands and peripheral vessels beneath the skin surface act as minute organs governed by the skin sympathetic nerves and have important physiological functions for body temperature control and nutrition support along with maintenance of a peripheral organization. Dynamics of the mental sweating of sweat glands and the peripheral vessels reflect the activity of a sympathetic nerve. The purpose of this paper is to study the dynamic observation and analysis of sweat glands and a peripheral vessels by optical coherence tomography (OCT). Materials and Methods: In the dynamic analysis of mental sweating of sweat glands, after confirmation of the resting state of the volunteer, mental stress was applied in the form of unpleasant sound for 0.5 sec; piled-up en-face OCT images of sweat glands were then obtained time-sequentially, with the frame-spacing of 3.3 sec. A swept-source (SS) OCT was used for in vivo en-face OCT of a group of sweat glands on the subject's fingertip. Furthermore, we conducted in vivo dynamic analysis in response to external mental stress of a peripheral vessel in the second joint of the subject's third finger using 1.3-µm SS OCT. Results: We analyzed time variation in the amount of excess sweat produced by a group of sweat glands and found a large difference in the amount of sweat stored by each sweat gland in the spiral lumen. Mental stress was also shown to cause the small artery of the finger to contract, reducing blood flow. In particular, the thickness of the tunica media of the small artery changed abruptly in response to the sound stress, increasing and then decreasing so that the artery contracted and expanded, respectively. Conclusions: Dynamic analysis of mental sweating in the eccrine sweat glands and changes in peripheral vessels was performed using time-sequential OCT imaging. For mental sweating, time variation in the amount of excess sweat produced could be simultaneously evaluated for a few tens of eccrine sweat glands. Furthermore, we performed the dynamic analysis of a peripheral vessel in a human finger in response to external mental stress and found that the small artery contracted and expanded in response to sound stress while continuing to pulse in synchronization with the heartbeat. These studies have the potential for establishing new knowledge about skin physiology.

해안 광학영상 자료를 이용한 쇄파지역 연안류 측정기술

In-situ measurements are labor-intensive, time-consuming, and limited in their ability to observe currents with spatial variations in the surf zone. This paper proposes an optical image-based method of measurement of currents in the surf zone. This method measures nearshore currents by tracking in time wave breaking-induced foam patches from sequential images. Foam patches in images tend to be arrayed with irregular pixel intensity values, which are likely to remain consistent for a short period of time. This irregular intensity feature of a foam patch is characterized and represented as a keypoint using an imagebased object recognition method, i.e., Scale Invariant Feature Transform (SIFT). The keypoints identified by the SIFT method are traced from time sequential images to produce instantaneous velocity fields. In order to remove erroneous velocities, the instantaneous velocity fields are filtered by binding them within upper and lower limits, and averaging the velocity data in time and space with a certain interval. The measurements that are obtained by this method are comparable to the results estimated by an existing image-based method of observing currents, named the Optical Current Meter (OCM).

Full-field spreading velocity measurement inside droplets impinging on a dry solid surface

This study investigates the radial velocity distributions during the early phase of spreading inside the water droplets impinging onto a heated sapphire glass surface as the second part of the author’s previous paper about the droplet impacts onto an unheated surface (Erkan and Okamoto in Exp Fluids 55:1–9, 2014). The surface was heated to the temperature values above the saturation temperature of the water and the droplets impinge with low-Weber numbers (in the range of 4–5) and high-Weber numbers (in the range of 10–15). Planar full-field velocity distributions were measured inside the expanding liquid lamella using time-resolved particle image velocimetry (TR-PIV), and the results were presented with the quantitative uncertainties. The PIV results revealed that radial velocity distributions demonstrated nonlinear and linear behaviors, as in the case of unheated surface impacts, at a single instant of time. By the time, they gained nonlinear forms, particularly in the outer radial positions owing to the vertically upward flows. An empirical time-dependent correlation in power-law form was proposed to formulate the temporal evolution of the velocity distributions covering all radial positions in the spreading droplet. The rate of change in the droplet radii was also measured from the time-sequential shadowgraph images. Spreading speeds resemble an extension of the PIV-velocity profiles, which verified the two different measurement methods. For the low-Weber number cases, the radial velocity magnitudes were detected to be lower than those of the unheated surface impacts, specifically in the later stages of the spreading. That is likely to be related to the increasing effect of thermocapillary flows or with the degree of curvature on the outermost interface of the spreading liquid lamella. The radial velocity measurements inside the droplets impinging onto the unheated surface were compared with an analytical model and a numerical simulation (OpenFOAM-VOF). The analytical model could predict spreading speeds of the droplets, while, as anticipated, it could not reproduce the nonlinearity of the velocity profiles, which might be responsible for the nonuniform convection of heat inside the expanding droplets on the hot surfaces. The numerical simulation could estimate the velocity profiles, even though some deviations detected between the experimental results and numerical results.

Radiographic visualization of magma dynamics in an erupting volcano

Radiographic imaging of magma dynamics in a volcanic conduit provides detailed information about ascent and descent of magma, the magma flow rate, the conduit diameter and inflation and deflation of magma due to volatile expansion and release. Here we report the first radiographic observation of the ascent and descent of magma along a conduit utilizing atmospheric (cosmic ray) muons (muography) with dynamic radiographic imaging. Time sequential radiographic images show that the top of the magma column ascends right beneath the crater floor through which the eruption column was observed. In addition to the visualization of this magma inflation, we report a sequence of images that show magma descending. We further propose that the monitoring of temporal variations in the gas volume fraction of magma as well as its position in a conduit can be used to support existing eruption prediction procedures.

Evaluation of Associated Motion Parameters of Descending Moon Impact Probe (MIP) of Chandrayan-1 from Time Sequential Images

The MIP, a micro satellite probe onboard Chandrayaan -1 was designed to impact on moon surface at pre decided location for scientific data collection from close range which was released from Chandrayaan-1 mother ship on 14 th November 2008. This MIP impacted near the moon surface near south-pole after 24 minutes from its release and while descending MIP suffered a composite motions consisting of three fundamental motions viz. spinning, coning and forward translational (velocity). Such descending MIP showed a definite pattern of coverage on moon surface. Therefore in order to monitor and to select future landing site of impact on moon surface the associated component of motion viz.; spinning rate, coning rate, velocity of descend of MIP needs to be calculated and known. In view of this, an attempt has been made here to derive associated parameters of composite motions and attitude of MIP for predicting future impact site of descending probe on moon surface from the orbiting space craft using the time sequential images acquired by the descending MIP and the algorithm developed under MATLAB after Srivastava et. al. 2011.